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1
Ebodaghe, Denis Abumere. "Estimating daily green leaf area index for corn in Virginia." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/74731.
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A model to predict the daily green leaf area index (GLAI) for corn has been developed for Indiana conditions. Using daily maximum and minimum temperatures the GLAI was predicted for the vegetative stage, reproductive and grain filling stage, and the leaf senescing stage of corn. Predictions of GLAI for corn can be made on a daily basis from the day corn is planted until it is harvested for grain.
The GLAI model was tested under Virginia conditions using green leaf area measurements collected from corn plants grown on Davidson silty clay loam, Davidson silty clay, and Mayodan sandy loam soils in the Piedmont region of the State. Maximum and minimum temperature data were also collected at the three sites. Measurements were made for two growing seasons using corn hybrid Pioneer 3369A, three plant population densities and two irrigation schedules. Short duration temperature data were also collected to compare with the daily maximum and minimum temperature data for the Mayodan site. Also a combination of soil temperature at 10 cm depth and air temperatures were used for the temperature functions accumulated from date of planting at the Mayodan site.
Results of this study show that the predicted and measured GLAI values compare favorably under irrigated conditions on the Davidson soil. The results were not as favorable on the irrigated corn on the Mayodan soil. When the corn is subjected to severe moisture stress on either soil, GLAI cannot be predicted with this model. Short duration temperature data resulted in a better prediction of GLAI on the Mayodan soil. When applying nitrogen fertilizer to the corn through the irrigation system through the grain filling stage, the measured GLAI values compared favorably with the predicted GLAI values. However, the application of nitrogen and sulfur fertilizer together resulted in GLAI being maintained above that predicted for a longer period of time during the grain filling stage before its decline.<br>Ph. D.
2
Malone, Sean M. "Assessment of Soybean Leaf Area for Redefining Management Strategies for Leaf-Feeding Insects." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29252.
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Commercially available leaf area index (LAI) meters are tools that can be used in making insect management decisions. However, proper technique must be determined for LAI estimation, and accuracy must be validated for the meters. Full-season soybean require LAI values of at least 3.5 to 4.0 by early to mid-reproductive developmental stages to achieve maximum yield potential, but the relationship between double-crop soybean LAI and yield is unknown. This research (1) evaluated minimum plot size requirements for mechanically defoliated soybean experiments using the LAI-2000 Plant Canopy Analyzer, (2) compared LAI estimates among LAI-2000 detector types which respond to different wavelengths of light, (3) compared LAI-2000 estimates with directly determined LAI values for 0, 33, 66, and 100% mechanical defoliation levels, (4) used linear and non-linear models to describe the response of full-season and double-crop soybean yields to reductions in LAI through mechanical defoliation, and (5) evaluated the response of double-crop soybean yields to reductions in LAI through insect defoliation.
The minimum plot size for obtaining accurate LAI estimates of defoliated canopies in soybean with 91 cm row centers is four rows by 2 m, with an additional 1 m at the ends of the two middle rows also defoliated. The wide-blue detector, which is found in newer LAI-2000 units and responds to wavelengths of light from 360 to 460 nm, gave higher LAI estimates than the narrow-blue detector, which responds to light from 400 to 490 nm. The unit with the narrow-blue detector gave estimates equal to directly determined LAI in two of three years for 0, 33, and 66% defoliation levels, while the units with the wide-blue detectors gave estimates higher than directly determined LAI in the two years that they were studied, except for a few accurate 33% defoliation estimates. Therefore, the LAI-2000 usually provides reasonable estimates of LAI. Yield decreased linearly with LAI when LAI values were below 3.5 to 4.0 by developmental stages R4 to R5 in both full-season and double-crop soybean. Usually, there was no relationship between yield and LAI at LAI values greater than 4.0. There was an average yield reduction of 820 ± 262 kg ha-1 for each unit decrease in LAI below the critical 3.5 to 4.0 level; maximum yields ranged from 1909 to 3797 kg ha-1. Insect defoliators did not defoliate double-crop soybean plots to LAI levels less than 4.0, and there was no yield difference between insect-defoliated and control plots. Therefore, double-crop soybean that maintains LAI values above the 3.5 to 4.0 critical level during mid-reproductive developmental stages is capable of tolerating defoliating pest<br>Ph. D.
3
Coker, Graham William Russell. "Leaf Area Index in Closed Canopies: An indicator of site quality." Thesis, University of Canterbury. School of Forestry, 2006. http://hdl.handle.net/10092/1128.
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This study examined leaf area index (LAI) and relationships with corresponding tree growth, climate and soil characteristics across New Zealand forest plantations. The aim of this study was to determine if quick measures of projected leaf area across environmental gradients of New Zealand were an accurate indicator of site quality. Projected leaf areas of Pinus radiata D Don and Cupressus lusitanica Mills seedlings were measured using a Li-Cor LAI-2000 plant canopy analyser at 22 locations representing the soil and climatic diversity across New Zealand plantation forests. Seedlings planted at 40 000 stems per hectare were used to test treatment effects of fertiliser, site disturbance and species over a 4 year period. It was hypothesised that collected climate and soil information would explain differences in LAI development patterns across sites as the canopies approached site and seasonal maxima. Averaged across sites Cupressus lusitanica 7.28 (± 2.59 Std.) m2 m-2 had significantly (p = 0.0094) greater projected LAIs than Pinus radiata 6.47 (± 2.29) m2m-2. Maximum site LAI (LAImax) varied from 2.9 to 11.8 m2 m-2 for Pinus radiata and from 3.1 to 12.6 m2 m-2 for Cupressus lusitanica. LAImax of both species was significantly and positively correlated with vapour pressure deficit, soil carbon, nitrogen, phosphorous and CEC, but negatively with solar radiation, temperature and soil bulk density. A seasonal model of LAI across sites illustrated an 8.5% fluctuation in LAI of established canopies over the course of a year. Despite considerable variation in climate and soil characteristics across sites the combined effects of LAI at harvest and temperature were significantly correlated with site productivity (r2 = 0.84 and 0.76 for Pinus radiata and Cupressus lusitanica respectively). A national model of LAImax (r2 = 0.96) was proposed for Pinus radiata across climate and soil environments and the significance of LAImax as a component of site quality monitoring tools is discussed.
4
Wang, Dongdong. "Improving satellite Leaf Area Index estimation based on various integration methods." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9872.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2009.<br>Thesis research directed by: Dept. of Geography. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
5
Johnson, Ryan L. "Airborne remote sensing of forest leaf area index in mountainous terrain." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ49131.pdf.
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Johnson, Ryan L., and University of Lethbridge Faculty of Arts and Science. "Airborne remote sensing of forest leaf area index in mountainous terrain." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2000, 2000. http://hdl.handle.net/10133/90.
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Leaf area index (LAI) provides forestry information that is important for regional scale ecological models and in studies of global change. This research examines the effects of mountainous terrain on the radiometric properties of multispectral CASI imagery in estimating ground-based optical measurements of LAI, obtained using the TRAC and LAI- 2000 systems. Field and image data were acquired summer 1998 in Kananaskis, Alberta, Canada. To account for the influence of terrain a new modified approach using the Li and Strahler Geometric Optical Mutual Shadowing (GOMS) model in 'multiple forward mode' (MFM) was developed. This new methodology was evaluated against four traditional radiometric corrections used in comination with spectral mixture analysis (SMA) and NDVI. The MFM approach provided the best overall predictions of LAI measured with ground-based optical instruments, followed by terrain normalized SMA, SMA without terrain normalization and NDVI.<br>xiv, 151 leaves : ill. (some col.), map ; 29 cm.
7
Fang, Hongliang. "Improving the estimation of leaf area index from multispectral remotely sensed data." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/304.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2003.<br>Thesis research directed by: Geography. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
8
Bowyer, P. "Estimating leaf area index in savanna vegetation using remote sensing and inverse modelling." Thesis, University of Salford, 2005. http://usir.salford.ac.uk/2234/.
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Leaf area index (LAI), defined as the one sided green leaf area per unit ground area, is a key parameter in ecosystem process models. Owing to the large area of the earth's surface that they occupy, savanna ecosystems represent the third largest terrestrial carbon sink. There is considerable uncertainty however, as to the functioning of these ecosystems, particularly as they respond to land cover changes. Consequently, ecosystem process models constitute one of the best methods available for investigating the effect this may have on terrestrial carbon cycling. If these models are to be used over large areas however, they need to be parameterised. This thesis develops a methodology to estimate LAI in savanna ecosystems, using remotely sensed earth observation (EO) data, laboratory bidirectional reflectance measurements (BRDF), physically based canopy reflectance models (CRMs), and artificial neural networks (ANN). First, the scattering behaviour of Kalahari soils was characterised, by making laboratory BRDF measurements. Soils were shown to be highly non-Lambertian. These measurements were then used to parameterise three different CRMs. Modelled reflectances were assessed with respect to Landsat ETM+ and Terra-MODIS reflectances. Results showed that a 1-D turbid medium provided the closest fit to the measurements. A series of model sensitivity analyses (SA) were performed, and it was shown that reflectance in the red and shortwave infrared displayed greatest sensitivity to LAI, sensitivity in the near-infrared was negligible. Model inversions were performed with ANN and different waveband combinations, and LAI was estimated. The results showed that LAI could be estimated with high accuracy, an RMSE of 0.3 1, and 0.18, from ETM+ and MODIS measurements, respectively. These results were promising, and with further improvements to models, coupled with more accurate input data, will see the use of EO data play an increasingly important role in understanding the functioning of these savanna ecosystems.
9
May, David Z. "A MULTISPECTRAL REMOTE SENSING INVESTIGATION OF LEAF AREA INDEX AT BLACK ROCK FOREST, NY." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1157569101.
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Hirooka, Yoshihiro. "Evaluation of Rice Growth Characteristics Based on Non-destructive Measurements of Leaf Area Index." Kyoto University, 2016. http://hdl.handle.net/2433/215581.
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Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(農学)<br>甲第19755号<br>農博第2151号<br>新制||農||1038(附属図書館)<br>学位論文||H28||N4971(農学部図書室)<br>32791<br>京都大学大学院農学研究科農学専攻<br>(主査)教授 白岩 立彦, 教授 奥本 裕, 教授 稲村 達也<br>学位規則第4条第1項該当
11
McCurdy, Wyatt Conner. "Characterizing spatiotemporal variation in LAI of Virginia Pine Plantations." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/96595.
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Loblolly pine is an important managed tree species within the southeastern United States, and better understanding spatial patterns in its productivity has potential to contribute to both modeling and management of the species. Using recently-created pine management maps specific to Virginia and empirical relationships predicting pine LAI from the Landsat satellite, we conducted a statewide analysis of temporal patterns in stand-level southern pine leaf area index (LAI) following clear-cut and planting. Here, using 28 years of Landsat time-series data for 13,140 stands that were clear-cut between 2014-2017, we examined 1) when LAI peaked over the rotation, and 2) how LAI in each stand compared to a recommended fertilization threshold of 3.5 LAI. We found that, on average, winter LAI reached a maximum of 2.02., which can be approximately doubled to give a summer LAI of 4.04, and within stand peak occurred between years 13 and 15. We also found that around 45.8% of stands achieved an LAI value higher than 3.5: a fertilization threshold recommended for managed stands in Virginia. The dataset produced by our analysis will bolster information required for modeling loblolly pines as a plant functional type in regional land simulations, and the finding that most stands are below the recommended LAI fertilization threshold will fuel further management-motivated research.<br>Master of Science<br>Management of pines in the southeastern U.S. contributes to the region's economy and carbon sequestration potential. In this study, we used Virginia forest harvest maps to identify individual patches (stands) of pine forest which had each gone through a full harvest life cycle (rotation). With unique managed pine stands identified, we used satellite imagery to estimate growth of canopy leaf area over time within each stand, using a metric called leaf area index (LAI). We identified 13,140 separate stands, each with up to 28 years of available data. We took the first full-state census of areas of managed pines in Virginia, and their leaf area development. We acquired one LAI measurement from February of each year, for each stand in Virginia. Using February LAI for each of our stands, we found that an average stand in VA has a maximum winter LAI of 2.02 (meaning an approximate maximum summer LAI of 4.04), and that stands generally reached their peak LAI after around 14 years of growth. It is recommended, in VA, that a landowner fertilize their stand in the middle of a harvest rotation if summer peak LAI is under 3.5, at stand closure. We found that at ten years of stand age, 45.8% of stands were estimated to reach above this threshold. Since this study's dataset is the most comprehensive LAI dataset for managed pines in VA, it may be used to improve management outcomes as well as understand pine productivity for land surface modeling purposes.
12
Bobeva, Albena. "Quantifying the distribution of forest functional types and forest leaf area index in the Alps." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969685106.
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Shah, Kushendra Narayan. "MULTI-SCALE MAPPING AND ACCURACY ASSESSMENT OF LEAF AREA INDEX FOR VEGETATION STUDY IN SOUTHERN ILLINOIS." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1234.
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The increasing interest of modeling global carbon cycling during the past two decades has driven this research to map leaf area index (LAI) at multiple spatial resolutions by combining LAI field observations with various sensor images at local, regional, and global scale. This is due to its important role in process based models that are used to predict carbon sequestration of terrestrial ecosystems. Although a substantial research has been conducted, there are still many challenges in this area. One of the challenges is that various images with spatial resolutions varying from few meters to several hundred meters and even to 1 km have been used. However, a method that can be used to collect LAI field measurements and further conduct multiple spatial resolution mapping and accuracy assessment of LAI is not available. In this study, a pilot study in a complex landscape located in the Southern Illinois was carried out to map LAI by combining field observations and remotely sensed images. Multi-scale mapping and accuracy assessment of LAI using aerial photo, Landsat TM and MODIS images were explored by developing a multi-scale sampling design. The results showed that the sampling design could be used to collect LAI observations to create LAI products at various spatial resolutions and further conduct accuracy assessment. It was also found that the TM derived LAI maps at the original and aggregated spatial resolutions successfully characterized the heterogeneous landscape and captured the spatial variability of LAI and were more accurate than those from the aerial photo and MODIS. The aerial photo derived models led to not only over- and under-estimation, but also pixilated maps of LAI. The MODIS derived LAI maps had an acceptable accuracy at various spatial resolutions and are applicable to mapping LAI at regional and global scale. Thus, this study overcame some of the significant gaps in this field.
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DeRose, Robert Justin. "Leaf Area Index - Relative Density Relationships in Even-Aged Abies Balsamea - Picea Rubens Stands in Maine." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/DeRoseRJ2004.pdf.
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Meek, David B. "The Relationship Between Leaf Area Index and Photosynthetic Temperature Response in Wheat (Triticum aestivum L.) Canopies." DigitalCommons@USU, 1990. https://digitalcommons.usu.edu/etd/6764.
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The objective of this study was to determine the effect of increasing leaf area index on the photosynthetic temperature response of a wheat canopy. Hard red spring wheat (Triticum aestivum L. cv. Veery-10) was grown hydroponically in a growth chamber, which also served as the gas-exchange chamber. Gas-exchange parameters were measured on single leaves and on wheat canopies at various leaf area indices. The temperature response curves of the canopy shifted from being steeper with a high temperature optimum to being flatter with a lower temperature optimum as leaf area index increased from 0 to 20.0 m2m-2. Single-leaf and canopy measurements show that this shift was primarily a result of increasing respiration from accumulating stems and reproductive structures and, to a lesser extent, from lower temperature optimums associated with lower light levels within the canopy.
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Hancock, Dennis Wayne. "SPECTRAL REFLECTANCE OF CANOPIES OF RAINFED AND SUBSURFACE IRRIGATED ALFALFA." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/332.
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The site-specific management of alfalfa has not been well-evaluated, despite the economic importance of this crop. The objectives of this work were to i) characterize the effects of soil moisture deficits on alfalfa and alfalfa yield components and ii) evaluate the use of canopy reflectance patterns in measuring treatment-induced differences in alfalfa yield. A randomized complete block design with five replicates of subsurface drip irrigation (SDI) and rainfed treatments of alfalfa was established at the University of Kentucky Animal Research Center in 2003. Potassium, as KCl, was broadcast on split-plots on 1 October 2004 at 0, 112, 336, and 448 kg K2O ha-1. In the drought year of 2005, five harvests (H1 - H5) were taken from each split-plot and from four locations within each SDI and rainfed plot. One day prior to each harvest, canopy reflectance was recorded in each plot. Alfalfa yield, yield components, and leaf area index (LAI) were determined. In 2005, dry matter yields in two harvests and for the seasonal total were increased (Pandlt;0.05) by SDI, but SDI did not affect crown density. Herbage yield was strongly associated with yield components but yields were most accurately estimated from LAI. Canopy reflectance within blue (450 nm), red (660 nm) and NIR bands were related to LAI, yield components, and yield of alfalfa and exhibited low variance (cv andlt; 15%) within narrow ( 0.125 Mg ha-1) yield ranges. Red-based Normalized Difference Vegetation Indices (NDVIs) and Wide Dynamic Range Vegetation Indices (WDRVIs) were better than blue-based VIs for the estimation of LAI, yield components, and yield. Decreasing the influence of NIR reflectance in VIs by use of a scalar (0.1, 0.05, or 0.01) expanded the range of WDRVI-alfalfa yield functions. These results indicate that VIs may be used to estimate LAI and dry matter yield of alfalfa within VI-specific boundaries.
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Aqeel, Abdullah Mohammad. "USING MANUAL DEFOLIATION TO SIMULATE SOYBEAN RUST: EFFECT ON GROWTH AND YIELD FORMATION." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/223.
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Field experiments were conducted in Kentucky and Louisiana in 2008 and 2009 (split-plot in a randomized complete block design with four replications) to investigate it is possible to simulate with manual defoliation the effect of soybean rust (SBR) (Phakopsora pachyrhizi Syd. and P. Syd) injury on a healthy soybean [Glycine max, (L.) Merr.] canopy, understand how defoliation affects the growth dynamics and canopy light interception, and if defoliation affectsleaf senescence and nitrogen remobilization during the seed-filling period. Two manual defoliation treatments based on changes in effective leaf area index (ELAI) (calculated as the reduction in leaf area equivalent to SBR-induced premature leaf abscission, loss in green leaf area, and reduction in photosynthetic capacity of diseased leaves) in infected canopies in Brazil were used to simulate SBR infection at growth stage R2 (full flowering) and R5 (beginning of seed-fill). Both defoliation treatments reduced yield in all experiments and the reduction was larger for the treatments at growth stage R2. The yield losses were equivalent to that observed in infected soybean canopies in Brazil. This suggests that a system of manual defoliation to simulate changes in effective leaf area duration shows promise as a tool to simulate the impact of SBR on soybean yield. The radiation use efficiency and crop growth rate from growth stage R2 to R5 were not influenced by defoliation. Defoliation started at growth stage R2 reduced seed number per unit area, while defoliation started at growth stage R5 reduced seed size due to shortening the seed-fill duration and a lower seed growth rate. There is no evidence that manual defoliation affected leaf senescence or nitrogen redistribution to the seed. This study found that the reduction of light interception by SBR was the main reason for the reductions in soybean growth and yield.
18
Pacheco, Anna. "Contribution of hyperspectral remote sensing to the estimation of leaf area index in the context of precision agriculture." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26734.
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The estimation of Leaf Area Index (LAI) is a key parameter controlling biophysical processes of the vegetation canopy, and ultimately yield. Defined as one half the total green leaf area per unit ground surface area, LAI is an essential component of precision crop management. Direct field techniques are tedious, time-consuming and labour-intensive. Indirect techniques, such as determining gap fraction with optical instruments have proven to be a good alternative, but their use is limited to rigid field sampling techniques. Vegetation indices have been useful to estimate LAI but are limited mostly due to its background reflectance noise. LAI can be estimated using different types of data, but only hyperspectral remote sensing has the potential to distinguish effectively the crop from other field components using spectral mixture analysis. Once the crop fraction has been derived, LAI is estimated using a crop fraction inversion technique. The application of this technique under agricultural field conditions has been very limited and not rigorously validated. The main objective of this study is to validate the crop fraction inversion technique for LAI estimation, and to examine the potential for LAI estimation using hyperspectral remote sensing data in the context of precision agriculture. This research will provide a unique scientific contribution to the field of hyperspectral remote sensing and greatly contribute to the advancement of remote sensing agriculture applications in Canada. (Abstract shortened by UMI.)
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Davidson, Diedre P., and University of Lethbridge Faculty of Arts and Science. "Sensitivity of ecosystem net primary productivity models to remotely sensed leaf area index in a montane forest environment." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2002, 2002. http://hdl.handle.net/10133/155.
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Net primary productivity (NPP) is a key ecological parameter that is important in estimating carbon stocks in large forested areas. NPP is estimated using models of which leaf area index (LAI) is a key input. This research computes a variety of ground-based and remote sensing LAI estimation approaches and examines the impact of these estimates on modeled NPP. A relative comparison of ground-based LAI estimates from optical and allometric techniques showed that the integrated LAI-2000 and TRAC method was preferred. Spectral mixture analysis (SMA), accounting for subpixel influences on reflectance, outperformed vegetation indices in LAI prediction from remote sensing. LAI was shown to be the most important variable in modeled NPP in the Kananaskis, Alberta region compared to soil water content (SWC) and climate inputs. The variability in LAI and NPP estimates were not proportional, from which a threshold was suggested where first LAI is limiting than water availability.<br>xii, 181 leaves : ill. ; 28 cm.
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Banskota, Asim. "The discrete wavelet transform as a precursor to leaf area index estimation and species classification using airborne hyperspectral data." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/39188.
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The need for an efficient dimensionality reduction technique has remained a critical challenge for effective analysis of hyperspectral data for vegetation applications. Discrete wavelet transform (DWT), through multiresolution analysis, offers oppurtunities both to reduce dimension and convey information at multiple spectral scales. In this study, we investigated the utility of the Haar DWT for AVIRIS hyperspectral data analysis in three different applications (1) classification of three pine species (Pinus spp.), (2) estimation of leaf area index (LAI) using an empirically-based model, and (3) estimation of LAI using a physically-based model. For pine species classification, different sets of Haar wavelet features were compared to each other and to calibrated radiance. The Haar coefficients selected by stepwise discriminant analysis provided better classification accuracy (74.2%) than the original radiance (66.7%). For empirically-based LAI estimation, the models using the Haar coefficients explained the most variance in observed LAI for both deciduous plots (cross validation R2 (CV-R2) = 0.79 for wavelet features vs. CV-R2 = 0.69 for spectral bands) and all plots combined (CV R2 = 0.71 for wavelet features vs. CV-R2 = 0.50 for spectral bands). For physically-based LAI estimation, a look-up-table (LUT) was constructed by a radiative transfer model, DART, using a three-stage approach developed in this study. The approach involved comparison between preliminary LUT reflectances and image spectra to find
the optimal set of parameter combinations and input increments. The LUT-based inversion was performed with three different datasets, the original reflectance bands, the full set of the wavelet extracted features, and the two wavelet subsets containing 99.99% and 99.0% of the cumulative energy of the original signal. The energy subset containing 99.99% of the cumulative signal energy provided better estimates of LAI (RMSE = 0.46, R2 = 0.77) than the original spectral bands (RMSE = 0.69, R2 = 0.42). This study has demonstrated that the application of the discrete wavelet transform can provide more accurate species discrimination within the same genus than the original hyperspectral bands and can improve the accuracy of LAI estimates from both empirically- and physically-based models.<br>Ph. D.
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Jones, Brian Paul. "Determination and Manipulation of Leaf Area Index to Facilitate Site-Specific Management of Double-Crop Soybean in the Mid-Atlantic, U.S.A." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31566.
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Double cropping soybean after small grain harvest does not always allow sufficient canopy growth to maximize photosynthesis and seed yield. This is due to a shorter growing season and moisture deficits common to the Mid-Atlantic USA. Leaf area index (LAI) is the ratio of unit leaf area of a crop to unit ground area and is a reliable indicator of leaf area development and crop biomass. An LAI of 3.5 to 4.0 by flowering is required to maximize yield potential. Soybean LAI will vary within and between fields due to soil differences, cultivar selection, and other cultural practices. Site-specific management strategies such as varying plant population may be used to manipulate LAI and increase yield in leaf area-limited systems. Furthermore, methods to remotely sense leaf area are in order to facilitate such management strategies in large fields. The objectives of this research were to: i) determine the effect of plant population density on soybean LAI and yield; ii) determine the relationship between LAI measured at different reproductive stages and yield; iii) investigate and validate relationships between LAI and yield for two cultivars in three crop rotations across varying soil moisture regimes; iv) validate relationships found in previous work between soybean LAI and yield across soil moisture regimes in grower fields; and v) determine if normalized difference vegetation index (NDVI) values obtained from aerial infrared images can be used to estimate LAI and soybean yield variability. Increasing plant population increased LAI for cultivars at Suffolk in 2000 and 2001, but LAI increased with plant populations on soils with lower plant available water holding capacity (PAWHC) at Port Royal in 2001. In 2000 at Suffolk, seed yield increased quadratically with increasing population and cultivar did not affect the response. In 2001, no relationship occurred between yield and plant population at either Suffolk or Port Royal, but the relationship of yield and LAI depended on soybean development stage at both sites. However, this relationship was not consistent between sites or years. In another study, crop rotation affected LAI and yield one out of two years. However, LAI and yield in both study years were negatively impacted on soil types with lower PAWHC. Where significant, a linear relationship was observed between yield and LAI for all soil types. Studies on grower fields showed similar linear relationships between yield and LAI. Remote sensing techniques showed promise for estimation of LAI and yield. When obtained at an appropriate development stage, vegetation indices correlated to both LAI and yield, and were observed to be effective as a predictor of LAI until plants achieved LAI levels of 3.5 to 4.0.<br>Master of Science
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Braun, Marko. "The Segmentation of Reflectances from Moderate Resolution Remote Sensing Data for the Retrieval of Land Cover Specific Leaf Area Index." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-75863.
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Kandasamy, Sivasathivel. "Leaf Area Index (LAI) monitoring at global scale : improved definition, continuity and consistency of LAI estimates from kilometric satellite observations." Phd thesis, Université d'Avignon, 2013. http://tel.archives-ouvertes.fr/tel-00967319.
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Monitoring biophysical variables at a global scale over long time periods is vital to address the climatechange and food security challenges. Leaf Area Index (LAI) is a structure variable giving a measure of the canopysurface for radiation interception and canopy-atmosphere interactions. LAI is an important variable in manyecosystem models and it has been recognized as an Essential Climate Variable. This thesis aims to provide globaland continuous estimates of LAI from satellite observations in near-real time according to user requirements to beused for diagnostic and prognostic evaluations of vegetation state and functioning. There are already someavailable LAI products which show however some important discrepancies in terms of magnitude and somelimitations in terms of continuity and consistency. This thesis addresses these important issues. First, the nature ofthe LAI estimated from these satellite observations was investigated to address the existing differences in thedefinition of products. Then, different temporal smoothing and gap filling methods were analyzed to reduce noiseand discontinuities in the time series mainly due to cloud cover. Finally, different methods for near real timeestimation of LAI were evaluated. Such comparison assessment as a function of the level of noise and gaps werelacking for LAI.Results achieved within the first part of the thesis show that the effective LAI is more accurately retrievedfrom satellite data than the actual LAI due to leaf clumping in the canopies. Further, the study has demonstratedthat multi-view observations provide only marginal improvements on LAI retrieval. The study also found that foroptimal retrievals the size of the uncertainty envelope over a set of possible solutions to be approximately equal tothat in the reflectance measurements. The results achieved in the second part of the thesis found the method withlocally adaptive temporal window, depending on amount of available observations and Climatology as backgroundestimation to be more robust to noise and missing data for smoothing, gap-filling and near real time estimationswith satellite time series.
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Johnson, Bryan Fisher. "Influence of Several Herbicides on Visual Injury, Leaf Area Index, and Yield of Glyphosate-Tolerant Soybean (Glycine max)." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32295.
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The occasional failure of glyphosate to control all weeds throughout the entire growing season has prompted growers to sometimes use herbicides other than glyphosate on glyphosate-tolerant soybean. Field studies were conducted in 1999 and 2000 to investigate potential crop injury from several herbicides on glyphosate-tolerant soybean, and to determine the relationship between soybean maturity, planting date, and herbicide treatment on soybean injury, leaf area index (LAI), and yield. Three glyphosate-tolerant soybean cultivars representing maturity groups III, IV and V were planted at dates representing the full-season and double-crop soybean production systems used in Virginia. Within each cultivar and planting date, 15 herbicide treatments, in addition to a control receiving only metolachlor preemergence, were applied to cause multiple levels of crop injury. Results of this study indicate that glyphosate-tolerant soybean generally recovered from early-season herbicide injury and LAI reductions; however, reduced yield occurred with some treatments. Yield reductions were more common in double-crop soybean than in full-season soybean. In full-season soybean, most yield reductions occurred only in the early maturing RT-386 cultivar. These yield reductions may be attributed to the reduced developmental periods associated with early maturing cultivars and double-crop soybean that often lead to reduced vegetative growth and limited LAI. Additional reductions of LAI by some herbicide treatments on these soybean may have coincided with yield reductions; however, reduced LAI did not occur with all yield reducing treatments. Therefore, soybean LAI response to herbicide treatments does not always accurately indicate the potential detrimental effects of herbicides on soybean yield. Further, yield reductions associated with herbicide applications occurred, although soybean sometimes produced leaf area exceeding the critical LAI level of 3.5 to 4.0 which is the minimum LAI needed for soybean to achieve maximum yield.<br>Master of Science
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Souza, Vanessa de Arruda. "Utilização de técnicas de sensoriamento remoto para a estimativa da evapotranspiração em uma cultura de arroz irrigado." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/72454.
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A evapotranspiração (ET) é um fenômeno natural que influencia diretamente mudanças no clima local e global, possuindo grande importância hidrológica e meteorológica. Este trabalho teve como objetivo estimar a ET através do método Penman-Monteith, e comparar com os resultados estimados pelo Método da Covariância de Vórtices Turbulentos. Os dados de IAF (Índice de Área Foliar) para descrição da vegetação foram obtidos a partir do sensor MODIS e de medições em campo da Rede SulFlux. A área de estudo desta pesquisa localizou-se no município de Cachoeira do Sul-RS, em uma propriedade de cultivo de arroz irrigado. O período de estudo referiu-se a safra que estendeu-se de outubro de 2010 a março de 2011. Os resultados mostraram que o IAF e as estimativas de ET apresentam um comportamento temporal semelhante. A comparação entre os resultados das estimativas de ET, utilizando dados obtidos em campo e estimados através de sensoriamento remoto, foram satisfatórios. No entanto, o resultado que apresentou os maiores valores para a ET foi proveniente do sensor MODIS. Sendo assim, pode-se concluir que a estimativa da ET, a partir de dados de vegetação, obtidos através de técnicas de sensoriamento remoto, constituem-se como uma alternativa para os métodos de ET que utilizam dados de vegetação medidos em campo.<br>The Evapotranspiration (ET) is a natural phenomenon that directly causes changes in the local and global climate, having a great hydrologic and meteorological importance. This work has as objective to estimate ET through the Penman-Monteith method and compare with the estimated results by the Eddy Covariance Method. The LAI (Leaf Area Index) data for the vegetation description were obtained from the MODIS sensor and from field measurements of the SulFlux network. The field of study of this research had place in the city of Cachoeira do Sul – Rio Grande do Sul state, in a irrigated rice crop property. The study period is referred to the crop that extended from October 2010 to March 2011. The results showed that the LAI and the ET estimates have a similar temporal behavior. The comparison between the results of ET estimates, using data obtained in field and estimated through remote sensing, were satisfactory. However, the result that showed the highest values for ET was from the MODIS sensor. This way, it can be concluded that the ET estimate, through vegetation data, obtained by remote sensing techniques, are an alternative for the ET methods that use vegetation field measured data.
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Chiang, Yang-Sheng. "Estimating landscape level leaf area index and net primary productivity using field measurements, satellite imagery, and a 2-D ecophysiological model." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1294241.
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This study has provided a landscape level estimate of leaf area index (LAI) and net primary productivity (NPP) for a temperate broadleaf forest ecosystem in south-central Indiana. The estimates were compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) biophysical products LAI and NPP from both spatial and temporal perspectives. The evidence suggests that field-based estimates were poorly correlated with global MODIS data due to the simplifying assumptions of the MODIS global applicability, saturation problems of the red reflectance in highly vegetated areas, homogeneous land cover types of the study area, and other design assumptions of the field-based estimates. To improve the localized applicability of MODIS product algorithms, an empirical and localized algorithm combining in-situ measurements, the buildup of a localized biophysical model, and remote sensing-derived data were suggested for each local-scaled ecosystem.<br>Department of Natural Resources and Environmental Management
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Hausler, Melanie. "Assessment of vegetation parameters in olive trees in the region of Alentejo. A comparison of direct and indirect methods." Master's thesis, ISA/UTL, 2011. http://hdl.handle.net/10400.5/4004.
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Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia<br>Vegetation parameters, as the leaf area index (LAI) and the ground cover (GC) are commonly related to biosphere processes, being used in models to estimate yield and crop water requirements. Several direct and indirect methods have been developed in the past decades to determine the LAI. However, a simple approach to assess this parameter is still missing. In this study we tested the operability and precision of different methods to calculate the LAI of 6 and 20 year old olive trees (Arbequina and Cobrançosa), under irrigated and non-irrigated conditions in the region of Alentejo. The average LAI on a projected area basis was estimated to be 5.88 and 2.75 m2 m-2 at the irrigated and non-irrigated sites, respectively, corresponding to 1.01 and 1.05 m2 m-2 on a total area basis. Furthermore, a tool was introduced to simplify the decision making between the use of the LAI and the GC. The determination of the GC is much easier than the LAI in practical uses. The average GC was 5.7 m2 under irrigated and 18.0 m2 under non-irrigated conditions. A detailed comparison between direct and indirect methods is given and the future prospective of the decision making tool is discussed.
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Ilangakoon, Nayani Thanuja. "Relationship between leaf area index (LAI) estimated by terrestrial LiDAR and remotely sensed vegetation indices as a proxy to forest carbon sequestration." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1402857524.
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Hawthorne, Iain. "Eddy-covariance carbon balance, photosynthetic capacity and vegetation indices in a harvested boreal jack pine stand." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2757.
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Eddy-covariance (EC) CO₂ flux data were analysed and annual carbon (C) balances estimated for a four-year period (2004-2007) following clearcut harvesting of a boreal jack pine stand in northern Saskatchewan. The site was a source of C to the atmosphere for all years, with annual net ecosystem productivity (NEP) increasing from -153 g C m⁻² yr⁻¹ in 2004 to -63 g C m⁻² yr⁻¹ in 2007. This increase was mainly due to gross primary productivity (GPP) increasing significantly from 78 to 200 g C m⁻² yr⁻¹ , while ecosystem respiration (R) increased only slightly from 231 to 263 g C m⁻² yr⁻¹ over the same period. In the 2006 growing season (GS), a field campaign was conducted to investigate the relationships between monthly destructive measurements of leaf area index (LAI) and daily measurements of the normalized difference vegetation index (NDVI) and photosynthetic capacity (Amax). The latter was derived from 5-day, 16-day, 30-day and annual Michaelis-Menten light response analyses using daytime measurements of NEP and incident photosynthetically active radiation. Digital-camera data were used to evaluate the potential of using the rectilinear-lens vegetation index (RLVI) as a surrogate for NDVI of a young forest stand. Results showed that LAI was linearly related to NDVI and RLVI, which was largely the result of changes in the deciduous vegetation component across the GS. These results indicate that RLVI could be used as a surrogate for NDVI up to a GS maximum LAI of 0.91 m2 m⁻² observed in 2006. Measured mean (± 1 S.D.) GS LAI was 0.67 (± 0.24) m² m⁻² in 2006. LAI accounted for the majority of the variability in Amax at the 30-day time scale, while at shorter time scales air temperature was the dominant control. For 2004 to 2007, mean spring estimates of LAI were 0.25, 0.29, 0.38 (compared to 0.40 m² m⁻² from measurements) and 0.41 m² m⁻², respectively. Results suggest that a steady increase in the jack pine LAI component accounted for the annual increases in GPP and hence NEP over the four years.
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Lima, Julianne Oliveira Sbeghen. "Aplicação de quatro métodos indiretos na medição de densidade de dossel em fragmento de mata nativa, recuperada e floresta de Eucalyptus urophylla (S.T. Blake)." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-25042017-151359/.
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A cobertura de dossel em uma floresta controla a quantidade, a qualidade e a distribuição da incidência de radiação solar, o que vem a refletir em diferentes níveis de umidade do solo, promovendo a interceptação das chuvas, consequentemente, reduzindo o seu impacto do solo. Além disso, a estrutura vegetal e a densidade do dossel condicionam não apenas o regime de radiação, mas também as trocas de energias e gases entre floresta e atmosfera. Este trabalho teve como objetivo comparar o uso do densiômetro, densitômetro, quadro reticulado e fotografias hemisféricas na obtenção da densidade do dossel visando encontrar uma metodologia de baixo custo e que garanta a mesma eficiência dos resultados de densidade de dossel obtidos de fotografias hemisféricas com máquina fotográfica. Resultados significativos foram obtidos para o uso do quadro reticulado, do densiômetro e da lente hemisférica fisheye clip para celular.<br>The canopy cover in a forest controls the solar radiation incidence quantity, quality and distribution, which it comes to reflect different levels of soil moisture, promoting the interception of rainfall and, thereafter, reducing its impact soil. Furthermore, plant canopy structure and density promotes not only the radiation system, but also energy and the exchange of gases between atmosphere and forest. This study aimed to compare the densiometer, densitometer lattice frame and hemispherical photographs uses on getting the canopy density in seeking a low methodology costs and guaranteeing the same efficiency of canopy density results hemispherical photographs with camera . This work presented significant results as the lattice frame, densiometer and hemispheric fisheye lens clip for mobile uses.
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Peduzzi, Alicia. "Estimating forest attributes using laser scanning data and dual-band, single-pass interferometric aperture radar to improve forest management." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/39456.
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The overall objectives of this dissertation were to (1) determine whether leaf area index (LAI) (Chapter 2), as well as stem density and height to live crown (Chapter 3) can be estimated accurately in intensively managed pine plantations using small-footprint, multiple-return airborne laser scanner (lidar) data, and (2) ascertain whether leaf area index in temperate mixed forests is best estimated using multiple-return airborne laser scanning (lidar) data or dual-band, single-pass interferometric synthetic aperture radar data (from GeoSAR) alone or both in combination (Chapter 4). In situ measurements of LAI, mean height, height to live crown, and stem density were made on 109 (LAI) or 110 plots (all other variables) under a variety of stand conditions. Lidar distributional metrics were calculated for each plot as a whole as well as for crown density slices (newly introduced in this dissertation). These metrics were used as independent variables in best subsets regressions with LAI, number of trees, mean height to live crown, and mean height (measured in situ) as the dependent variables. The best resulting model for LAI in pine plantations had an R2 of 0.83 and a cross-validation (CV) RMSE of 0.5. The CV-RMSE for estimating number of trees on all 110 plots was 11.8 with an R2 of 0.92. Mean height to live crown was also well-predicted (R2 = 0.96, CV-RMSE = 0.8 m) with a one-variable model. In situ measurements of temperate mixed forest LAI were made on 61 plots (21 hardwood, 36 pine, 4 mixed pine hardwood). GeoSAR metrics were calculated from the X-band backscatter coefficients (four looks) as well as both X- and P-band interferometric heights and magnitudes.
Both lidar and GeoSAR metrics were used as independent variables in best subsets regressions with LAI (measured in situ) as the dependent variable. Lidar metrics alone explained 69% of the variability in temperate mixed forest LAI, while GeoSAR metrics alone explained 52%. However, combining the LAI and GeoSAR metrics increased the R2 to 0.77 with a CV-RMSE of 0.42. Analysis of data from active sensors shows strong potential for eventual operational estimation of biophysical parameters essential to silviculture.<br>Ph. D.
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Ding, Deng. "An integrated modeling framework of socio-economic, biophysical, and hydrological processes in Midwest landscapes: remote sensing data, agro-hydrological model, and agent-based model." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1840.
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Intensive human-environment interactions are taking place in Midwestern agricultural systems. An integrated modeling framework is suitable for predicting dynamics of key variables of the socio-economic, biophysical, hydrological processes as well as exploring the potential transitions of system states in response to changes of the driving factors. The purpose of this dissertation is to address issues concerning the interacting processes and consequent changes in land use, water balance, and water quality using an integrated modeling framework. This dissertation is composed of three studies in the same agricultural watershed, the Clear Creek watershed in East-Central Iowa.
In the first study, a parsimonious hydrologic model, the Threshold-Exceedance-Lagrangian Model (TELM), is further developed into RS-TELM (Remote Sensing TELM) to integrate remote sensing vegetation data for estimating evapotranspiration. The goodness of fit of RS-TELM is comparable to a well-calibrated SWAT (Soil and Water Assessment Tool) and even slightly superior in capturing intra-seasonal variability of stream flow. The integration of RS LAI (Leaf Area Index) data improves the model's performance especially over the agriculture dominated landscapes. The input of rainfall datasets with spatially explicit information plays a critical role in increasing the model's goodness of fit.
In the second study, an agent-based model is developed to simulate farmers' decisions on crop type and fertilizer application in response to commodity and biofuel crop prices. The comparison between simulated crop land percentage and crop rotations with satellite-based land cover data suggest that farmers may be underestimating the effects that continuous corn production has on yields (yield drag). The simulation results given alternative market scenarios based on a survey of agricultural land owners and operators in the Clear Creek Watershed show that, farmers see cellulosic biofuel feedstock production in the form of perennial grasses or corn stover as a more risky enterprise than their current crop production systems, likely because of market and production risks and lock in effects. As a result farmers do not follow a simple farm-profit maximization rule.
In the third study, the consequent water quantity and quality change of the potential land use transitions given alternative biofuel crop market scenarios is explored in a case study in the Clear Creek watershed. A computer program is developed to implement the loose-coupling strategy to couple an agent-based land use model with SWAT. The simulation results show that watershed-scale water quantity (water yield and runoff) and quality variables (sediment and nutrient loads) decrease in values as switchgrass price increases. However, negligence of farmers risk aversions towards biofuel crop adoption would cause overestimation of the impacts of switchgrass price on water quantity and quality.
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Brantley, Steven T. "Seasonal and Spatial Variation in Leaf Area Index, Litter Production, and Light Levels in Myrica Cerifera,Shrub Thickets Across a Barrier Island Chronsequence." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1507.
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Leaf area index (LAI), litter production and understory light levels of Myrica cergera shrub thickets were assessed on Hog Island, Virginia to quantify spatial and seasonal variations in leaf area and light attenuation among four thickets representing a successional chronosequence and compare methods of estimating LA1 in shrub- dominated systems. Seasonal LA1 estimates were made seven times throughout the year with a portable integrating radiometer (Li-Cor LAI-2000) and three times by measurement of photosynthetically active radiation (PAR) and use of the Beer-Larnbert law. Leaf area index was also estimated through leaf litter collection and use of allometric relationships between stem diameter and leaf area. The oldest of the four thickets had the lowest LA1 and litter production throughout the year. Peak LA1 measurements with the portable integrating radiometer ranged from 2.0 ± 0.2 to 4.0 ± 0.3 for the oldest and youngest thickets, respectively which appear to be substantial underestimates of the actual values. According to annual litterfall, LA1 ranged from 4.1 ± 0.5 for the oldest thicket to 10.2 ± 0.4 for a 20 year old thicket. Leaf area index varied from 6.4 ± 0.2 for the oldest thicket to 1 1.4 ± 2.1 for the 40 year old thicket according to the allometric relationships, which may overestimate LA1 in stands with many large stems. The high light attenuation by the shrub canopy and heavy litterfall may contribute to the low diversity within thicket canopies by inhibiting germination and growth of other species. The study demonstrates that these low diversity shrub thickets have a higher LA1 and litter production, and thus higher potential for primary productivity, than many temperate forested systems and that stand age may be the major determinant of productivity.
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Asam, Sarah [Verfasser], Stefan [Gutachter] Dech, and Harald [Gutachter] Kunstmann. "Potential of high resolution remote sensing data for leaf area index derivation using statistical and physical models / Sarah Asam. Gutachter: Stefan Dech ; Harald Kunstmann." Würzburg : Universität Würzburg, 2015. http://d-nb.info/1111636680/34.
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Uehara, Luciana Yukari. "Inflluência do microrrelevo em caracteres foliares de espécies do sobosque de Floresta Ombrofila Densa Submontana, no Núcleo Piciguaba, Ubatuba." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315566.
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Orientador: Sandra Maria Carmello-Guerreiro, Fernando Roberto Martins<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia<br>Made available in DSpace on 2018-08-17T07:29:42Z (GMT). No. of bitstreams: 1
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Previous issue date: 2010<br>Resumo: Características morfológicas e anatômicas da folha de espécies vegetais são importantes indicadores de sua ecologia e dos habitats que ocupam. A variação das características anatômicas das folhas relacionadas às diferentes condições ambientais como deficiência hídrica, luminosidade, tipo de solo e disponibilidade de nutrientes é interpretada como resposta ecofisiológica da planta
às diferenças microclimáticas. Dentre as características morfo-anatômicas, a área foliar, a área foliar específica (AFE), a densidade estomática, a espessura total da lâmina, a espessura do parênquima paliçádico, a espessura da epiderme, a quantidade de tecido esclerenquimático e a razão entre o tecido paliçádico e lacunoso, são alguns caracteres que podem ser utilizados para avaliar o grau de escleromorfismo de uma vegetação. Características edáficas, como disponibilidade de água e de nutrientes, pH, textura, podem sofrer variações devido a condições do relevo, como declividade. As variações do relevo estão intrinsecamente relacionadas com a disponibilidade hídrica e nutricional, exercendo grande influência em características da vegetação local. O objetivo deste estudo foi descrever e analisar características da morfológicas e anatômicas de folhas de espécies em diferentes microrrelevos, em um fragmento de Floresta Ombrófila Densa Submontana, na região da Serra do Mar, Estado de São Paulo.<br>Abstract: Plant species morphological and anatomical leaf traits are important indicators of their ecology and habitats. The variation of leaf anatomical traits, in relation to different environmental conditions, such as water stress, light, soil type, nutrient availability, is interpreted as ecophysiological response of plants to microclimatic differences. Among the morpho-anatomical traits, leaf area, specific leaf area (SLA), stomatal density, total thickness of leaf blade, the thickness of palisade parenchyma, thickness of epidermis, the amount of sclerenchyma, the ratio of palisade and spongy tissue, are some traits that can be used to assess the degree of scleromorphy of vegetation. Soil characteristics, such as availability of water and nutrients, pH, texture, may vary due to relief conditions, such as slope. Relief variations are intrinsically related to water and nutrient availability, exercising great influence on the characteristics of local vegetation. The aim of this study was to describe and analyze morphological and anatomical characteristics of leaves of herbaceous species on different micro-relief in a fragment Lower Montane Rain Forest in the Serra do Mar, State of Sao Paulo.<br>Mestrado<br>Biologia Vegetal<br>Mestre em Biologia Vegetal
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Gaiewski, Vicente. "Parametrização do modelo LINTUL para estimar a produtividade potencial da cultura de milho." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-10112009-152845/.
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Com o objetivo de parametrizar o modelo LINTUL (Light Interception and Utilization - Interceptação e Utilização da Luz) foi conduzido um experimento de campo, na safra 2003/2004, em Piracicaba-SP, na área experimental do Departamento de Produção Vegetal (Esalq) da Universidade de São Paulo, utilizando o procedimento de análise de crescimento. Ao longo do ciclo da cultura, foram efetuadas 24 amostragens, com 4 repetições, para determinação da massa de matéria seca de raiz, colmo, folha e órgão reprodutivo. Em função dos resultados obtidos referentes à parametrização do modelo LINTUL com base na comparação dos valores medidos e estimados do índice de área foliar (erro relativo entre -3,6 e +3,9%) e da produtividade potencial (erro relativo entre -1,0 e +3,2%) de grãos da cultura de milho, os valores dos parâmetros são: (i) escala: diária (1 dia); (ii) soma térmica entre a semeadura e emergência: 115oC.dia; (iii) soma térmica entre a emergência e o florescimento: 902oC.dia; (iv) soma térmica entre o florescimento e o ponto de maturidade fisiológica: 1009ºC.dia; (v) área foliar específica: 0,036 m2.g-1; (vi) índice de área foliar inicial: 0,017 m2.m-2 (BRS-1001 e BRS-3003) e 0,022 m2.m-2 (BRS-1010); (vii) índice de área foliar crítico: 5,7 m2.m-2; (viii) temperatura basal inferior: 10oC; temperatura basal superior: 40oC; (ix) temperatura ótima inferior: 28oC; (x) temperatura ótima superior: 35oC; (xi) eficiência do uso da radiação: 2,38 g.MJ-1 e (xii) coeficiente de extinção de luz: 0,7 m2.m-2.<br>With the purpose of parameterizing the LINTUL (Light Interception and Utilization) model a field experiment was carried out, during the season 2003/2004, in Piracicaba, state of São Paulo, Brazil, in the experimental area of Crop Science Department (Esalq) of University of São Paulo, using the crop growth analysis procedure. During the crop cycle, 24 sampling were done, with 4 replications, for root, stem, leaf and storage organ dry matter measurements. According to parameterization results of the LINTUL model based on comparison of the measured and estimated values of the leaf area index (relative error between -3.6 and +3.9%) and of the corn crop potential productivity (relative error between -1.0 and +3.2%), the parameters values are: (i) scale: daily (1 day); (ii) thermic index between sowing and emergence: 115oC.day; (iii) termic index between emergence and flowering: 902oC.day; (iv) termic index between flowering and physiological maturity point: 1009ºC.day; (v) specific leaf area: 0.036 m2.g-1; (vi) initial leaf area index: 0.017 m2.m-2 (BRS-1001 and BRS-3003) and 0.022 m2.m-2 (BRS-1010); (vii) critical leaf area index: 5.7 m2.m-2; (viii) basal temperature (inferior): 10oC; (ix) basal temperature (superior): 40oC; (x) optimum temperature (inferior): 28oC; (xi) optimum temperature (superior): 35oC; (xii) radiation efficiency use: 2.38 g.MJ-1 and (xiii) light extintion coefficient: 0.7 m2.m-2.
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Jaboinski, Fernando Roberto. "Avaliação de produtos do sensor MODIS para aplicações na estimativa de parâmetros biofísicos da cultura da soja no estado do Rio Grande do Sul." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/36964.
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Estimativas do rendimento da soja são informações importantes que podem auxiliar as instituições na tomada de decisão quanto à políticas de comercialização. São consideradas também, na liberação de recursos para o financiamento da produção e seguro agrícola. Modelos matemáticos, que se baseiam nas relações clima planta, denominados modelos agrometeorológicos, podem estimar o rendimento médio de grãos, através de dados meteorológicos e biofísicos da cultura, como exemplo: o IAF (Índice de área foliar) da soja pode ser associado ao Kc (Coeficiente de cultura) para estimar o estádio fenológico, e esta informação, ser associada à parametrização dos modelos. O objetivo geral deste trabalho foi avaliar as possibilidades de se utilizar imagens do sensor MODIS, para estimar parâmetros biofísicos da soja, aplicáveis à modelagem do rendimento de grãos. A área de estudo abrangeu a porção norte do estado do Rio Grande do Sul. Foram obtidas as imagens do IAF, MOD15A2, e dos índices de vegetação NDVI (Índice de vegetação por diferença normalizada) e NDWI (Índice de umidade por diferença normalizada), do produto MOD13Q1. Foram analisadas duas safras: 2003/04 e 2004/05. O período de safra foi de 15 de outubro até 30 de abril. Foram geradas máscaras de cultivo para as safras, e aplicadas sobre as imagens. Inicialmente, foram comparadas as médias do IAF, MOD15A2, às outras estimativas do IAF obtidas a partir de funções de relação com o NDVI, e analisados os diagramas de dispersão para cinco datas. Então foi estimado o Kc_1 com as médias do IAF, MOD15A2, conforme Martorano (2007), e comparadas ao Kc_2 ajustado conforme Matzenauer, 2002. Foi calculado o balanço hídrico meteorológico da cultura a fim de se obter o Índice de Satisfação das Necessidades de Água das plantas (ISNA), sendo ISNA_1 considerando o Kc_1, e o ISNA_2, o Kc_2. Foram obtidos os índices de correlação entre o ISNA_1 e 2 e os índices NDVI e NDWI, para o ciclo completo da cultura e para períodos de baixo ISNA. Como resultado, o IAF, MOD15A2 apresentou coerência com a evolução do IAF durante o ciclo, porém, em média, apresentou valores inferiores aos observados por Fontana et al. (1992) e Martorano (2007). Já como estimador do Kc, apresentou coeficientes de variação inferiores ao observado no Kc_2. Observou-se também que no IAF, MOD15A2 ocorriam valores superestimados do Kc entre a semeadura e o máximo desenvolvimento, e após, subestimados, o que potencializou períodos de déficit hídrico acentuado durante a floração e enchimento de grãos, em ambas as safras. Já, avaliando os índices de correlação, o ISNA_1, apresentou correlações de maior significância com os índices de vegetação do que o ISNA_2. Com isso podemos supor que, mesmo o IAF, MOD15A2 não tendo apresentado valores compatíveis com os da soja, demonstrou maior significância nas correlações, o que indica que imagens MODIS, podem gerar estimativas adequadas tanto do IAF, quanto do Kc, e também, representar adequadamente as condições hídricas. É recomendável avaliar estimativas do IAF da soja, a partir de suas relações com o NDVI, a fim de se obter resultados compatíveis com a soja.<br>Estimates of soybean yield are useful information that can assist institutions in decisions related by commercial policies. It is considered also in financing of production and agricultural insurance. Mathematical models, which are based in clime plant relationship known as Agrometeorological Models, can provide an estimate for grain yield through meteorological and biophysical data correlated with the culture, as an example: the LAI (Leaf Area Index) of soybean can be related with the Kc (Culture's coefficient) to estimate the phenological stage, and this information, applied to model's parameters. The main objective of this work was evaluated of possibilities of MODIS's images, in estimation of biophysical parameters, which are applicable in yield's modeling for soybean. The studying area was a portion of northern of State of Rio Grande do Sul. Were obtained images from LAI, MOD15A2, and vegetation indexes, NDVI (Normalized Difference Vegetation Index) and NDWI (Normalized Difference Water Index) from MOD13Q1 product. Were analyzed two harvests: 2003/04 and 2004/05. The length of time for harvest was 15th October to 30th April. Soybean's areas was detected and masks were applied on the images. Firstly, were compared the means between LAI, MOD15A2 and two different methodologies of LAI's estimation based on relationship with NDVI. The scatter plots were discussed between LAI, MOD15A2 and other methodologies, for five key-dates. The culture's coefficient Kc_1 was estimated through LAI, MOD15A2, according to Martorano (2007), and compare with Kc_2, which were obtained from fitted culture's coefficient by Matzenauer (2002). The water balance were calculated aiming the index for Plant's water satisfaction needs (ISNA), which, ISNA_1 has considered the Kc_1, and ISNA_2, the Kc_2. Correlation indexes were obtained between ISNA_1 and 2, and vegetation indexes NDVI and NDWI, for the whole culture's cycle and specific periods of low ISNA. As results, LAI, MOD15A2, has presented coherence with soybean's cycle progress, however, as a rule, it presents lower values, comparing to Fontana et al. (1992) and Martorano (2007). Even now as a Kc's estimator, Kc_1 has presented lower variation's coefficient compared to Kc_2. Was observed also overrated in Kc_1 between the sowing to maximum development, and after, underestimated, what provokes periods of accented hydric deficiency during flowering and grain forming stages, in both harvests. Now, as to correlation's indexes, we observed more significance correlations between both vegetation's indexes and ISNA_1. This way, these results has indicated that remote sensing images can provide accurate estimates of IAF as much as Kc, and also indicate the hydric conditions of plants. It is recommended to improve the LAI's mean values on the images, exploring the relationship with NDVI, looking for adequate values for the case of soybean.
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Flores, Karen Stephanny Cordova. "Estudo das respostas ecofisiológicas no crescimento de clones Eucalyptus spp. submetidos a variações de níveis de restrições hídricas em distintas condições edáficas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-28032016-121014/.
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A alta demanda por madeira de eucalipto para diversas finalidades traz a necessidade da expansão de plantios para áreas em condições de déficit hídrico, o que leva o interesse de entender os processos fisiológicos relacionados ao crescimento da árvore, para possibilitar uma alta produtividade das florestas nessas áreas. Com base nessas informações, o objetivo deste trabalho foi avaliar o efeito da variação de níveis de restrições hídricas em clones de Eucalyptus spp. plantados em diferentes condições edáficas, pelo estudo das respostas ecofisiológicas, para isso foram instalados em janeiro 2012 dois experimentos na Estação Experimental de Ciências Florestais de Itatinga (EECFI) pertencente a Escola Superior de Agricultura \"Luiz de Queiroz\" (ESALQ) - USP, o experimento 1 foi instalado no solo classificado como Latossolo vermelho distroférrico típico A moderado textura argilosa (LVdf) e o experimento 2 no solo Latossolo vermelho distrófico típico A moderado textura argilosa (LVd-1).Cada experimento foi implantado em blocos casualizados em arranjo fatorial de 6 x 3, seis clones de eucalipto (COP 1404, COP 1407, AEC 1528, AEC 0042, AEC 0224, AEC 0144) e três espaçamentos (3m x1m, 3mx2m, e 3mx4m), com seis repetições, e parcelas quadradas constituídas por 25 plantas, sendo as nove plantas centrais consideradas como a área útil de medição. Foram realizadas avaliações das variáveis: DAP (cm), altura total (m), comprimento da copa (m) e índice de área foliar (IAF m2/m2) trimestralmente, no período de 21 até 37 meses de idade para as variáveis altura total e DAP, e o comprimento da copa e IAF a partir do mês 27. Para a mensuração do IAF foram utilizados dois equipamentos LAI-2000, onde a coleta de dados foi fora e sob o dossel. O folhedo foi coletado mensalmente em todas as parcelas. A avaliação da eficiência e uso de água foi aos 29 e 35 meses, analisando área foliar e as caraterísticas estomáticas em quatro blocos, nos quais três árvores foram amostradas sistematicamente. Para avaliação no incremento de diâmetro no tronco, se instalaram faixas dendrométricas em duas árvores por parcela e as leituras foram quinzenais, sendo correlacionadas com variáveis climáticas no período de 15 e 45 dias de defasagem. Os clones que apresentaram melhor desenvolvimento e estratégia do uso da água foram AEC 1528, AEC 0144 e AEC 0042 obtendo como respostas: maior DAP, altura total, comprimento da copa, área foliar, diâmetro estomático, e menor IAF e concentração de estômatos. Em relação ao peso de folhedo depositado verificou-se que a tendência de deposição oscilou no decorrer do tempo em função da fenologia da planta. Na dinâmica de crescimento cambial os incrementos apresentaram correlações com as variáveis climáticas, principalmente com a precipitação pluviométrica, quanto maior a defasagem maior a correlação. Correlacionando todas as variáveis, os clones apresentaram distintos padrões de respostas ecofisiológicas.<br>Eucalypts plantations are expanding to drought áreas in Brazil in order to attend the high demand of eucalypts wood for various purposes. Therefore, the understanding the physiological process related to tree growth in this condition is one of the research priorities. This study aimed to evaluate the effect of ecophysiological responses to water restrictions levels in growth of Eucalyptus spp clones, planted in different soil conditions. The two field experiments were planted in January 2012 at the Itatinga Experimental Station, College of Agriculture \"Luiz de Queiroz\" (ESALQ), São Paulo State University. Experiment 1 was planted on a site which the soil is classified as \"A moderate typical dystrophic Red Latosol with clay texture (LVdf)\" and experiment 2 on \"A moderate typical dystrophic Red Latosol with clay texture (LVd- 1)\". The experiments were established in a randomized block design with factorial 6 x 3 arrangement [six eucalypts clones (COP 1404, COP 1407, AEC 1528 AEC 0042, AEC 0224, AEC 0144) and three spacings (3m x1m, 3mx2m and 3mx4m)], with six replications, and square plots (5x5 trees). The measurements were carried out on the nine central trees. From the 21 to 37 months of age, the following variables were assessed every three months: DBH (diameter at breast height in cm), height (m) and crown length (m). Leaf area index (LAI m2 / m2) was evaluated every three months after 27 months of age. Two LAI-2000 equipments were used to measure the LAI, one under and another out of the canopy. Litter was collected monthly on all plots. The efficiency of water use was evaluated at 29 and 35 months of age, based on leaf area and stomatal characteristics of samples collected in three trees sampled systematically in four blocks. Dendrometer belts were used to evaluate the diameter growth of two trees per plot. Data collected fortnightly from dendrometers belts were correlated with climatic variables with 15 and 45-da lags. AEC 1528, AEC 0144 and AEC 0042 clones showed higher DBH, total height, crown length, leaf area, stomatal diameter and lower IAF and stomatal concentration, showing better strategy of water use and growth. Deposition of litter fluctuated over time and varied with the tree phenology. Cambium growth dynamics correlated with climate variables, especially with the rainfall. Higher correlations were observed with higher measured lag. Clones showed distinct patterns of ecophysiological responses when the correlations of all variables were considered.
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LaJeunesse, Katherine J. "Covariation in plant abundance and diversity estimators in an old field herbaceous plant community." Miami University Honors Theses / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1177560873.
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Gonsalves, Marcus Vinicius Irano [UNESP]. "Doses de N e K aplicadas via fertirrigação e espaçamento entre plantas influenciando o desenvolvimento, a produtividade e as relações hídricas em melancieira com e sem sementes." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/88216.
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gonsalves_mvi_me_jabo.pdf: 689037 bytes, checksum: 058c47573833b69b7eb15e04313f24be (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>A melancieira é cultivada praticamente em todo o território brasileiro, atingindo produção média anual no período de 1999/2006 de 1826134,5 t em área média anual de 81891,8 ha no mesmo período. A produção e qualidade dos frutos de melancia estão associadas a fatores genéticos, climáticos e fitotécnicos, sendo a nutrição da planta de fundamental importância para conseguir resultados satisfatórios. O nitrogênio e o potássio são os nutrientes extraídos em maior quantidade pela melancia e devem ser aplicados de forma e quantidade adequada e na época correta. Outro fator de grande importância no manejo cultural é o espaçamento, pois determina alterações morfofisiológicas na planta que repercutem no seu potencial produtivo e, também, no tamanho, formato e qualidade da hortaliça. Foram feitos dois experimentos, um com o híbrido Shadow (triplóide sem semente) e outro com o híbrido com semente Top Gun com o objetivo de avaliar os efeitos da aplicação via fertirrigação de doses de nitrogênio e potássio combinada com espaçamentos entre plantas na linha de plantio no desenvolvimento foliar e na produtividade da cultura para o híbrido sem sementes e para o híbrido com sementes. E também de avaliar o efeito dos espaçamentos no armazenamento de água no solo nos dois híbridos. Ambos os experimentos utilizaram o delineamento em blocos casualizados, em parcelas subdivididas, com quatro tratamentos principais e quatro tratamentos secundários, e três repetições. Os tratamentos principais corresponderam às doses de aplicação de N e K via fertirrigação (75%, 100%, 125% e 150% de 106,4 e 118 kg ha-1 de N e K, respectivamente). Os tratamentos secundários corresponderam aos espaçamentos entre plantas de 0,5, 1,0, 1,5 e 2,0 m, mantendo-se fixo o espaçamento de 2,0 m entre linhas de plantio. As mudas foram transplantadas em 05-08-2008, com uma folha não...<br>The watermelon is cultivated in virtually all of Brazil, reaching an average annual production over the period 1999/2006 of 1,826,134.5 tons in annual average area of 81,891.8 ha in the same period. The production and fruit quality of watermelon are associated with genetic factors, climatic elements and cultivar characteristics, and the plant nutrition is of fundamental importance for achieving satisfactory results. Nitrogen and potassium are the nutrients extracted in greater quantity by watermelon and should be applied in right quantity and at the correct time. Another factor of great importance in crop management is the spacing between plants, because it determines the plant morpho-physiological changes which result in their productive potential and also the size, shape and quality of vegetables. Two experiments were made, one with the Shadow Hybrid (triploid seedless) and the other with the hybrid with seed Top Gun with the objective of to evaluate the effects of doses of nitrogen and potassium applied by fertigation combined with spacing between plants on the line in leaf development and crop yield for hybrid seedless and the hybrid with seeds. And also to evaluate the effect of spacing on the water storage in the soil in the two hybrids. Both experiments used a randomized block design in split plots with four main treatments and four secondary treatments, and three replications. The main treatments corresponded to application of doses of N and K applied by fertigation (75%, 100%, 125% and 150% of 106.4 and 118 kg ha-1 of N and K, respectively). Secondary treatments corresponded to the spacing between plants of 0.5, 1.0, 1.5 and 2.0 m, keeping constant the spacing of 2.0 m between lines. The seedlings were transplanted on 05-08-2008, with a not-cotyledonary leaf fully grown. Were evaluated the leaf area index (LAI), leaf water potential, commercial and total productivity of ... (Complete abstract click electronic access below)
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Soma, Maxime. "Estimation de la distribution spatiale de surface et de biomasse foliaires de couverts forestiers méditerranéens à partir de nuages de points acquis par un LIDAR terrestre." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0111.
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Pour mieux comprendre le fonctionnement des écosystèmes forestiers à échelle fine, les modèles écophysiologiques cherchent à intégrer les flux d’énergie et de matière. Ces échanges dépendent de la distribution de la végétation. Leur modélisation nécessite donc une description de la structure de la végétation en trois dimensions (3D) à un niveau de détail que seule la télédétection peut produire à haut débit. Les LiDAR terrestre (Light Detection And Ranging) possèdent un fort potentiel pour caractériser en 3D la végétation au sein des canopées. De précédents travaux qui relient la densité de points à la quantité de végétation ont montré des résultats prometteurs. Cette thèse développe ces approches en explorant les diverses sources d’erreurs. Les biais systématiques sont corrigés à l’échelle de la branche, de l’arbre et de la placette. Ce travail s’appuie à la fois sur des travaux théoriques et expérimentaux. Nous avons d’abord évalué des estimateurs théoriques sur des branches. Sur cette végétation réelle, les estimateurs se sont révélés sensibles à la taille de voxel utilisée et à la distance de mesure. Les corrections apportées sont demeurées robustes sur des arbres entiers. Cependant, l’échantillonnage au LiDAR terrestre est limité par l’occlusion végétale. Un travail spécifique a été conduit pour optimiser les estimations en tirant avantage des corrélations spatiales présentes dans la végétation. Cette approche permet de limiter les sous-estimations systématiques liées à l’occlusion. L’ensemble des outils présentés offrent la possibilité de dresser des cartes de végétation à l’échelle de la placette en fournissant des estimateurs non biaisés de la surface foliaire<br>To better understand functioning of forest ecosystems at fine scale, ecophysiological model attempt to include energy and material fluxes. Such exchanges depend on the distribution of vegetation. Hence, these models require a tridimensional (3D) description of vegetation structure, at a level of detail which can only be retrieve with remote sensing at large scale. Terrestrial LiDAR (Light Detection And Ranging) have a great potential to provide 3D description of vegetation elements in canopy. Previous studies established promising relations between the point density and quantity of vegetation. This work develop these statistical methods, focusing on source of errors. Systematic biases are corrected at branch, tree and plot scales. This study relies on both numerical simulations and field experiments. First, we test estimators on branches in laboratory conditions. On this natural vegetation, estimators are sensitive to voxel size and distance from instrument with phase-shift LiDAR. Developed corrections from this branch experiment are valid at tree scale. However, difficulties arising from sampling limitations due to occlusion and instrument sampling pattern cause negative biases in dense areas. Specific investigations are conducted to identify source of errors and to optimize multiscan estimations. A statistical method called LAD-kriging, based on spatial correlation within vegetation, improves local accuracy of estimations and limits underestimations due to occlusion. The tools produced in this work allow to map vegetation at plot scale by providing unbiased estimator of leaf area. Some of these tools are currently implemented within open access Computree software
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Solontsi, Mhlangabezi. "The response of maize to selected ratios of organic fertilizers mixed with inorganic fertilizers in Ndlambe Local Municipality, Eastern Cape, South Africa." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020902.
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The majority of small-scale farmers in the Eastern Cape apply inadequate quantities of manure, inorganic (NPK) fertilizer and Gromor as lone fertilizers or tend to mix manure or Gromor with chemical fertilizers for crops, without any scientific basis (Mkile, 2001). Hence this study – aimed at achieving effective and efficient use of chemical fertilizers, manure and Gromor, either as lone fertilizers or mixed with one another, in maize production – was established. A three-year dry land field experiment, arranged in a RCBD with 3 replicates where cattle manure, chemical fertilizer and Gromor were mixed at different ratios – as treatments FM1 (10 percent fertilizer + 90 percent manure); FM2 (25 percent fertilizer + 75 percent manure); FM3 (50 percent fertilizer + 50 percent manure); MAP (100 percent fertilizer); M (100 percent cattle manure); FG1 (10 percent fertilizer + 90 percent Gromor); FG2 (25 percent fertilizer + 75 percent Gromor); FG3 (50 percent fertilizer + 50 percent Gromor); G (100 percent Gromor) and a control (with nothing applied) – was conducted at the Nolukhanyo agricultural project at Bathurst in the Ndlambe Local Municipality. Maize cultivars PAN 6480 and Sahara were used as test crops. Manure, Gromor and soil were analyzed for their nutrient composition. Data recorded involving number of kernels per cob-1, grain and dry matter (DM) yields for the 2010-11, 2011-12 and 2012-13 seasons, and leaf area index (LAI) – were subjected to Genstat Version 14.1 for statistical analysis. Grain yields of PAN 6480 and Sahara recorded in seasons 2010-11, 2011-12 and 2012-13 were significantly higher (p≤0.05) than those of the controls. In 2012-13, PAN 6480 on treatments FG3 and FG1 produced the highest grain yields (5 327 and 5 107kg ha-1) respectively, while in 2010-11 the highest yield was 3 780kg ha-1. In the 2012-13 season, Sahara on F treatment was the highest with 4 553kg ha-1 whilst there were no significant differences in F and M treatments. Dry matter yields of Sahara were higher than those of PAN 6480 in all seasons. The highest Sahara LAI obtained on FM2 was 5.85 in the 2012-13 season, whereas PAN 6480 had LAI of 4.77 on F treatment, followed by FG3 with 4.72 LAI. PAN 6480 number of leaves for 6 plants in m2 and LAI in week 8 of the 2012-13 season had a positive correlation, r2=0.84. PAN 6480 number of kernels and cob length in the same area correlated quite well (r2 =0.91). Chemical fertilizer corrects the imbalances of nutrients inherent in organic manures and increases both maize grain yields and dry matter yields, and also influences number of leaves and LAI. Treatments FG1, FG3 and FM1 of PAN 6480 resulted in high maize grain yields when planted 13 in late November of the 2012-13 growing season and when water in the soil profile was conserved as a result of good rains received prior to planting. Treatments FG1 (10 percent fertilizer + 90 percent Gromor), FG3 (50 percent fertilizer + 50 percent Gromor) of PAN 6480 produced the highest grain yields (5 107kg ha-1 and 5 327kg ha-1 respectively) in the 2012-13 season, whilst FM1 (10 percent fertilizer + 90 percent manure) gave the highest grain yield (of 4 277kg ha-1) for the same cultivar in the 2010-11 season.
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Gonsalves, Marcus Vinicius Irano. "Doses de N e K aplicadas via fertirrigação e espaçamento entre plantas influenciando o desenvolvimento, a produtividade e as relações hídricas em melancieira com e sem sementes /." Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/88216.
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Resumo: A melancieira é cultivada praticamente em todo o território brasileiro, atingindo produção média anual no período de 1999/2006 de 1826134,5 t em área média anual de 81891,8 ha no mesmo período. A produção e qualidade dos frutos de melancia estão associadas a fatores genéticos, climáticos e fitotécnicos, sendo a nutrição da planta de fundamental importância para conseguir resultados satisfatórios. O nitrogênio e o potássio são os nutrientes extraídos em maior quantidade pela melancia e devem ser aplicados de forma e quantidade adequada e na época correta. Outro fator de grande importância no manejo cultural é o espaçamento, pois determina alterações morfofisiológicas na planta que repercutem no seu potencial produtivo e, também, no tamanho, formato e qualidade da hortaliça. Foram feitos dois experimentos, um com o híbrido Shadow (triplóide sem semente) e outro com o híbrido com semente Top Gun com o objetivo de avaliar os efeitos da aplicação via fertirrigação de doses de nitrogênio e potássio combinada com espaçamentos entre plantas na linha de plantio no desenvolvimento foliar e na produtividade da cultura para o híbrido sem sementes e para o híbrido com sementes. E também de avaliar o efeito dos espaçamentos no armazenamento de água no solo nos dois híbridos. Ambos os experimentos utilizaram o delineamento em blocos casualizados, em parcelas subdivididas, com quatro tratamentos principais e quatro tratamentos secundários, e três repetições. Os tratamentos principais corresponderam às doses de aplicação de N e K via fertirrigação (75%, 100%, 125% e 150% de 106,4 e 118 kg ha-1 de N e K, respectivamente). Os tratamentos secundários corresponderam aos espaçamentos entre plantas de 0,5, 1,0, 1,5 e 2,0 m, mantendo-se fixo o espaçamento de 2,0 m entre linhas de plantio. As mudas foram transplantadas em 05-08-2008, com uma folha não ... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The watermelon is cultivated in virtually all of Brazil, reaching an average annual production over the period 1999/2006 of 1,826,134.5 tons in annual average area of 81,891.8 ha in the same period. The production and fruit quality of watermelon are associated with genetic factors, climatic elements and cultivar characteristics, and the plant nutrition is of fundamental importance for achieving satisfactory results. Nitrogen and potassium are the nutrients extracted in greater quantity by watermelon and should be applied in right quantity and at the correct time. Another factor of great importance in crop management is the spacing between plants, because it determines the plant morpho-physiological changes which result in their productive potential and also the size, shape and quality of vegetables. Two experiments were made, one with the Shadow Hybrid (triploid seedless) and the other with the hybrid with seed Top Gun with the objective of to evaluate the effects of doses of nitrogen and potassium applied by fertigation combined with spacing between plants on the line in leaf development and crop yield for hybrid seedless and the hybrid with seeds. And also to evaluate the effect of spacing on the water storage in the soil in the two hybrids. Both experiments used a randomized block design in split plots with four main treatments and four secondary treatments, and three replications. The main treatments corresponded to application of doses of N and K applied by fertigation (75%, 100%, 125% and 150% of 106.4 and 118 kg ha-1 of N and K, respectively). Secondary treatments corresponded to the spacing between plants of 0.5, 1.0, 1.5 and 2.0 m, keeping constant the spacing of 2.0 m between lines. The seedlings were transplanted on 05-08-2008, with a not-cotyledonary leaf fully grown. Were evaluated the leaf area index (LAI), leaf water potential, commercial and total productivity of ... (Complete abstract click electronic access below)<br>Orientador: Luiz Carlos Pavani<br>Coorientador: Arthur Bernardes Cecílio Filho<br>Banca: Leila Trevizan Braz<br>Banca: Raimundo Leite Cruz<br>Mestre
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Imran, Hafiz Ali. "Remote Sensing Tools for Monitoring Grassland Plant Leaf Traits and Biodiversity." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/329592.
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Grasslands are one of the most important ecosystems on Earth, covering approximately one-third of the Earth’s surface. Grassland biodiversity is important as many services provided by such ecosystems are crucial for the human economy and well-being. Given the importance of grasslands ecosystems, in recent years research has been carried out on the potential to monitor them with novel remote sensing techniques. Improved detectors technology and novel sensors providing fine-scale hyperspectral imagery have been enabling new methods to monitor plant traits (PTs) and biodiversity.
The aims of the work were to study different approaches to monitor key grassland PTs such as Leaf Area Index (LAI) and biodiversity-related traits. The thesis consists of 3 parts: 1) Evaluating the performance of remote sensing methods to estimate LAI in grassland ecosystems, 2) Estimating plant biodiversity by using the optical diversity approach in grassland ecosystems, and 3) Investigating the relationship between PTs variability with alpha and beta diversity for the applicability of the optical diversity approach in a subalpine grassland of the Italian Alps
To evaluate the performance of remote sensing methods to estimate LAI, temporal and spatial observations of hyperspectral reflectance and LAI were analyzed at a grassland site in Monte Bondone, Italy (IT-MBo). In 2018, ground temporal observations of hyperspectral reflectance and LAI were carried out at a grassland site in Neustift, Austria (AT-NEU). To estimate biodiversity, in 2018 and 2019 a floristics survey was conducted to determine species composition and hyperspectral data were acquired at two grassland sites: IT-MBo and University of Padova’s Experimental Farm, Legnaro, Padua, Italy (IT-PD) respectively. Furthermore, in 2018, biochemistry analysis of the biomass samples collected from the grassland site IT-MBo was carried out to determine the foliar biochemical PTs variability.
The results of the thesis demonstrated that the grassland spectral response across different spectral regions (Visible: VIS, red-edge: RE, Near-infrared: NIR) showed to be both site-specific and scale-dependent. In the first part of the thesis, the performance of spectral vegetation indices (SVIs) based on visible, red-edge (RE), and NIR bands alongside SVIs solely based or NIR-shoulder bands (wavelengths 750 - 900 nm) was evaluated. A strong correlation (R2 > 0.8) was observed between grassland LAI and both RE and NIR-shoulder SVIs on a temporal basis, but not on a spatial basis. Using the PROSAIL Radiative Transfer Model (RTM), it was demonstrated that grassland structural heterogeneity strongly affects the ability to retrieve LAI, with high uncertainties due to structural and biochemical PTs co-variation.
In the second part, the applicability of the spectral variability hypothesis (SVH) was questioned and highlighted the challenges to use high-resolution hyperspectral images to estimate biodiversity in complex grassland ecosystems. It was reported that the relationship between biodiversity (Shannon, Richness, Simpson, and Evenness) and optical diversity metrics (Coefficient of variation (CV) and Standard deviation (SD)) is not consistent across plant communities. The results of the second part suggested that biodiversity in terms of species richness could be estimated by optical diversity metrics with an R2 = 0.4 at the IT-PD site where the grassland plots were artificially established and are showing a lower structure and complexity from the natural grassland plant communities. On the other hand, in the natural ecosystems at IT-MBo, it was more difficult to estimate biodiversity indices, probably due to structural and biochemical PTs co-variation. The effects of canopy non-vegetative elements (flowers and dead material), shadow pixels, and overexposed pixels on the relationship between optical diversity metrics and biodiversity indices were highlighted.
In the third part, we examined the relationship between PTs variability (at both local and community scales, measured by standard deviation and by the Euclidean distances of the biochemical and biophysical PTs respectively) and taxonomic diversity (both α-diversity and β-diversity, measured by Shannon’s index and by Jaccard dissimilarity index of the species, families, and functional groups percent cover respectively) in Monte Bondone, Trentino province, Italy. The results of the study showed that the PTs variability metrics at alpha scale were not correlated with α-diversity. However, the results at the community scale (β-diversity) showed that some of the investigated biochemical and biophysical PTs variations metrics were associated with β-diversity. The SVH approach was also tested to estimate β-diversity and we found that spectral diversity calculated by spectral angular mapper (SAM) showed to be a better proxy of biodiversity in the same ecosystem where the spectral diversity failed to estimate alpha diversity, this leading to the conclusion that the link between functional and species diversity may be an indicator of the applicability of optical sampling methods to estimate biodiversity.
The findings of the thesis highlighted that grassland structural heterogeneity strongly affects the ability to retrieve both LAI and biodiversity, with high uncertainties due to structural and biochemical PTs co-variation at complex grassland ecosystems. In this context, the uncertainties of satellite-based products (e.g., LAI) in monitoring grassland canopies characterized by either spatially or temporally varying structure need to be carefully taken into account. The results of the study highlighted that the poor performance of optical diversity proxies in estimating biodiversity in structurally heterogeneous grasslands might be due to the complex relationships between functional diversity and biodiversity, rather than the impossibility to detect functional diversity with spectral proxies.
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Gomes, Ellen da Costa. "Estrutura e produÃÃo do capim-tifton 85 sob duas intensidades e duas frequÃncias de desfolhaÃÃo com ovinos." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16329.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico<br>O processo de desfolhaÃÃo, composto pela intensidade e frequÃncia, interfere nos padrÃes de crescimento, nas caracterÃsticas estruturais e produtivas das plantas forrageiras. O conhecimento dessas respostas à essencial para a utilizaÃÃo da planta forrageira em pastagens. Esse estudo foi conduzido com o objetivo de avaliar as caracterÃsticas estruturais e produtivas em capim-tifton 85 sob efeitos de duas frequÃncias e duas intensidades de desfolhaÃÃo, manejado sob lotaÃÃo rotativa com ovinos. O experimento foi conduzido no NÃcleo de Ensino e Estudos em Forragicultura â NEEF/DZ/CCA/UFC, Fortaleza, CearÃ, de marÃo a dezembro de 2015, em uma Ãrea com capim-tifton 85. Os tratamentos corresponderam a combinaÃÃes entre duas frequÃncias (85 e 95% de interceptaÃÃo da radiaÃÃo fotossinteticamente ativa - IRFA) e duas intensidades de desfolhaÃÃo (1,0 e 1,8 de Ãndice de Ãrea foliar residual - IAFr), alocadas Ãs unidades experimentais segundo arranjo fatorial 2x2 e delineamento inteiramente casualizado, com quatro repetiÃÃes, totalizando 16 unidades experimentais de 40 m2. O pastejo foi realizado por ovinos da raÃa Morada Nova, manejados sob lotaÃÃo rotativa utilizando a tÃcnica de mob-stocking. As avaliaÃÃes de IRFA e IAF foram feitas com o aparelho analisador PAR-LAI em agricultura modelo AccuPAR LP-80. Foram avaliadas no pÃs e prÃ-pastejo as seguintes variÃveis: interceptaÃÃo da radiaÃÃo fotossinteticamente ativa, Ãndice de Ãrea foliar, altura do dossel e a densidade populacional de perfilhos. Avaliou-se tambÃm a biomassa de forragem total residual e de seus componentes e o acÃmulo de forragem total e de seus componentes. Verificou-se menor (P<0,05) perÃodo de descanso nos pastos sob manejo 85x1,8 e o maior nos pastos com 95x1,0. A altura residual foi superior (P<0,05) nos pastos sob manejo 95x1,0 e 85x1,8 comparados Ãqueles sob manejo 85x1,0. Os pastos com freqÃÃncia 95% de IRFA tiveram altura prÃ-pastejo maior (P<0,05) do que nos pastos com 85% de IRFA. Houve reduÃÃo (P<0,05) na populaÃÃo de perfilhos totais e aÃreos prÃ-pastejo nos pastos manejados com 95% de IRFA e com IAFr de 1,0. O acÃmulo de lÃmina foliar verde foi maior (P<0,05) nos pastos manejados com 95x1,0, contudo tambÃm houve maior (P<0,05) acÃmulo de colmo verde e de forragem morta nestes pastos comparado ao tratamento 85x1,0. O capim-tifton 85 manejado sob frequÃncia de 85% IRFA e IAFr de 1,0 apresentou estrutura e composiÃÃo morfolÃgica mais adequadas para pastejo por ovinos.<br>The process of defoliation, composed of intensity and frequency, interfere in the growth pattern, the structural and productive characteristics of forage crops. Knowledge of these answers is essential to the use of grasses in pastures. This study was conducted to evaluate the structural and productive characteristics on Tifton 85 grass under two frequencies and two intensities of defoliation, managed under intermitente stocking with sheep. The experiment was conducted at NÃcleo de Ensino e Estudo em Forragicultura â NEEF/DZ/CCA/UFC, Fortaleza, Ceara, from March to December of 2015, in a area of Tifton 85 grass. The treatments were combinations between two frequencies (85 and 95% of interception of photosynthetically active radiation - IPAR) and two intensities of defoliation (1.0 and 1.8 of residual leaf area index - LAI), in a 2x2 factorial arrangement and a completely randomized design, with four replications, totaling 16 experimental units of 40 mÂ. The grazing was carried out by Morada Nova sheep, managed under intermittent stocking using the mob- stocking technique. For IPAR and LAI evaluations a canopy analyzer equipment was used - AccuPAR LP-80 (DECAGON Device). The following variables were evaluated in the post and pre-grazing: interception of photosynthetically active radiation, leaf area index, canopy height and tiller density. It was evaluated also the total residual forage biomass and its components and the total accumulation of forage and its components. It has been found lower (P<0,05) rest period in pastures under management 85x1.8 and higher in pastures with 95x1.0. The residual height was higher (P<0,05) in pastures under 95x1.0 and 85x1.8 management compared to those under 85x1.0 management. Pastures with frequency 95% of IPAR had higher pre-grazing height (P<0,05) than pastures with 85% of IPAR. There was a reduction (P<0,05) in the total and aerial tiller population pre-grazing in the pastures managed with 95% of IPAR and residual LAI 1,0. The green leaf blade accumulation was higher (P<0,05) in pastures managed under 95x1.0, however, there was also greater (P<0,05) accumulation of green stem and dead forage in these pastures compared to 85x1.0 treatment. Tifton 85 grass managed under 85% IPAR and residual LAI 1.0 presented better structure and morphological composition for grazing with sheep.
46
Santos, Nailson Lima. "Avaliação do Capim-tanzânia manejado com diferentes IAF residuais sob lotação rotacionada por cabras Boer X Saanen /." Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/96575.
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Resumo: Avaliou-se o efeito do IAF residual sob a estrutura do pasto de capim-Tanzânia e o comportamento ingestivo de cabras Boer X Saanen sob lotação intermitente. O experimento foi conduzido no período de fevereiro/2008 a agosto/2008. A área foi subdividida em 18 piquetes de 243 m2 para o estudo de 3 tratamentos dispostos segundo um delineamento em blocos casualizados com 6 repetições para avaliações referentes à gramínea. As avaliações referentes ao comportamento ingestivo das cabras foram realizadas, na mesma área, em 12 piquetes, alocados em blocos casualizados, com 4 repetições. Os tratamentos consistiram em 3 IAF residuais (0,8 - 1,6 - 2,4). O período de descanso foi adotado segundo o critério de 95% de IL ou quando as leituras permanecerem constantes durante 3 semanas consecutivas. Antes do pastejo foi feito a medição da altura da vegetação em 20 pontos distintos e colheu-se 6 amostras ao nível do solo por piquete. Os animais pastejaram até atingir o IAF pré-determinado para o resíduo. Foi aferido o índice de área foliar (IAF) e da interceptação luminosa (IL) com o aparelho analisador de dossel (AccuPAR LP-80 da Decagon - USA). As amostras colhidas foram pesadas e, por conseguinte, retirada um alíquota de 400 g para a separação dos componentes morfológicos (folha, colmo + bainha e material morto), estes foram secados em estufa (55 ºC) por 72h e pesados, a fim de estimar as características estruturais. Avaliou-se a densidade volumétrica da forragem, com o auxílio do "ponto inclinado" e feita as análises laboratoriais a fim de estimar o que os caprinos consumiram durante o pastejo. As amostras analisadas foram colhidas pelo método do pastejo simulado. Também foram mensuradas variáveis que refletem o comportamento ingestivo em pastejo como a massa, a área, a profundidade e a taxa do bocado. No pré-pastejo, os valores de interceptação... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The effect residual LAI was evaluate under structural characteristics of tanzania grass and the ingestivo behavior by goats Saanen X Boer at rotational stocking. The experiment was conducted in the period on February/2008 to August/2008. The area was divided into 18 paddocks of 243 m2 for the study with 3 treatments arranged in a randomized blocks design with 6 replications for the grasses evaluations. The evaluations relating to the ingestive behavior of the goats were carried out, in the same area, in 12 paddocks, allocated in randomized blocks design with 4 replications. The treatments consisted in 3 levels of residual LAI (0,8 - 1,6 - 2,4). The period of rest was adopted according to the criterion of 95% of LI or when the readability remained constant during 3 consecutive weeks. Before each period of grazing have been done 20 points of height of vegetation were taken, 6 samples at the level of the soil were collected for each paddock . The animals grazed until the the remainder LAI pre-determined. Measurements were made of leaf area index (LAI) and the light interception (LI) with the equipment AccuPAR LP-80 Decagon - USA. Samples were weighed and, 400 g were kept for the separation of morphologic components (leaf, stem lap and dead). These were dried at 55° C for 72h and weighed in order to estimate the herbage mass. Density was evaluated by volume of forage with the inclined point quadrat. Laboratory analyzes were done in order to estimate the goats fed during the grazing and the samples were collected by the handing plucking method. They were measured variables which reflect the ingestive behavior in grazing as the bite mass, area, depth and the rate . Pre-grazing, the values of light interception and leaf area index were not significantly affected by treatments (P>0.05). The values of time of pre grazing of the animals... (Complete abstract click electronic access below)<br>Orientadora: Ana Cláudia Ruggieri<br>Coorientadora: Izabelle Auxiliadora Molina de Almeida Teixeira<br>Banca: Ricardo Andrade Reis<br>Banca: Carlos Augusto de Miranda Gomide<br>Mestre
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Hofmann, Gabriel Selbach. "Relações entre a temperatura do ar e a estrutura de formações vegetais no norte do Pantanal de Mato Grosso." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/15817.
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A relação entre o microclima e a vegetação tem sido explorada sob os mais variados pontos de vista. Raros são os trabalhos deste tipo, que consideram mais de um tipo de floresta, e em situação natural. Este trabalho avalia de forma detalhada a temperatura do ar, e sua relação com a estrutura da vegetação da maior Unidade de Conservação particular do País, a RPPN SESC Pantanal. Esta Unidade de Conservação se localiza em uma área continental tropical de grande importância para a conservação biológica, o Pantanal de Mato Grosso no centro-oeste do Brasil. Foi mensurada a estrutura de cinco formações florestais (Cambarazal, Mata com Acuri, Mata Densa, Tabocal e Mata Seca) e uma savânica (Campo com Murundus). Com uso de sensores de temperatura acoplados a data loggers e instalados dentro das formações, realizou-se comparações com um campo aberto, que funcionou como controle durante toda a amostragem. Para testar a influência da estrutura da vegetação no microclima, foram realizadas cinco regressões lineares múltiplas, onde a variável dependente era a diferença da temperatura registrada em campo aberto (delta) e de 36 unidades amostrais (6 por formação). Como variáveis preditivas foram empregados dados estruturais levantados nas mesmas. Foram observadas diferenças estruturais significativas entre as seis formações. Através dos dados de vegetação e de temperatura foi possível separar as formações vegetais em três grupos distintos; o das formações semi-abertas (Campo com Murundus, Tabocal e Mata Seca), abertas (campo aberto usado como controle dos dados meteorológicos) e das formações fechadas com coberturas de dosséis densos (Cambarazal, Mata com Acuri e Mata Densa). Foram encontradas diferenças térmicas superiores a 10ºC para todas as formações em relação ao campo aberto (exceto Campo com Murundu). As maiores diferenças foram registradas nos períodos de aquecimento e resfriamento dos dias. A explicação para isto está na grande velocidade de incremento e perda de calor do campo frente às demais formações que apresentaram maior estabilidade térmica. As regressões múltiplas revelaram um poder de explicação entre 43,3 e % e 63,8% e revelaram que o índice de área foliar (LAI) como a variável preditiva mais importantes para variações térmicas.<br>The relation between microclimate and vegetation has been explored under the most varied points of view. However, studies that consider more than one type of forest are rare, mainly in natural situation. This study evaluates in detail the air temperature and its relation to the vegetation structure of the largest Private Reserve of the Natural Wealth owned by de Social Service of Commerce, the RPPN SESC Pantanal. It is located in a tropical continental area of great importance for biological conservation, the Pantanal of Mato Grosso in mid-west of Brazil. The structure of five types of forest formations (Cambarazal, Mata com Acuri, Mata Densa, Tabocal e Mata Seca) and one savanna (Campo com Murundus) was measured. Temperature sensors coupled to data loggers were installed inside each of the vegetal formations as well as one station at open field to be used as control. To test influence of vegetation structure on microclimate, five multiple linear regressions were performed. The response variable was the temperature difference between recorded in open field and each of the 36 sampling units (6 by formation). Predictive variables were structural data verified at the same places. The difference in vegetation structure between the six types of vegetation was significant. The analysis of vegetation and temperature data allowed to distinguish the vegetal formations in three distinct groups: partialy open (Campo com Murundus, Tabocal e Mata Seca); open areas (open field); closed formations (Cambarazal, Mata com Acuri e Mata Densa). Thermal differences greater than 10°C were found for all vegetal formations when compared to open field (except for Campo com Murundu). The largest differences were recorded during the daily periods of warming (morning) and cooling (afternoon). The reason is the high speed of increment and loss of heat in open field relative to the other formations that showed higher thermal stability. The multiple regressions revealed a power of explanation between 43,3% and 63,8% and revealed the leaf area index (LAI) as the most important predictive variable to the thermal variations.
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Oliveira, Ana Paula Pessim de. "Crescimento e composi??o qu?mico-bromatol?gica do capim Tifton 85 (Cynodon spp) sob doses de nitrog?nio." Universidade Federal Rural do Rio de Janeiro, 2008. https://tede.ufrrj.br/jspui/handle/tede/579.
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Previous issue date: 2008-07-11<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>The effects of nitrogen (N) application on several structural and nutritional attributes of
the plant canopy were evaluated. The studies were carried out at the Experimental
Campus of the Rio de Janeiro Federal Rural University, Serop?dica-RJ, in area of
Planosol Haplic occurrence, during the period of October 2006 to July 2007. Treatments
consisted of five doses of N (0; 150; 300; 450 and 600 kg N-urea/ha) disposed in
experimental units of 4 x 4 m using a entirely randomized block design. After a
standardization cut, made 82 days after planting, it proceeded to the application of
nitrogen fertilizer levels, half of which at 94 days, and the remaining at 139 days after
the planting. Four studies had been carried through, which the results are presented in
distinct chapters. In the first chapter the results of nitrogen fertilization were discussed in
terms of soil covering, leaf area index (LAI) and solar radiation interception, during the
four sequential cuts, between the months of February and July of 2007. Weekly
evaluations were accomplished, between 10 and 40 days after cut. The LAI frequency of
occurrence, plant height, green cover index and level of photosynthetically active
radiation intercepted showed significant responses to N fertilization, according to a
logistic pattern and also varied seasonally within each cut, evidencing different
sensibility as indicators for structure and growth of the Tifton 85 sward. In the second
study were evaluated the effect of N fertilization on biomass production and the
efficiency in the use of N absorbed. For statistical analysis purposes, sampling data were
clustered in two seasons: rainy season (February to April) and dry season (April to
July). It was quantified in each cut date the production of green and dry mass, leaves and
stem fraction, as well as the N content in each one of the vegetative fractions. This study
showed that N fertilization icreased the dry matter production and stimulated the
production of leaves and stems in both the seasons (rainy and dry). However, the
nitrogen fertilization, per se, does not modify the partition of the dry mass produced by
leaves and stems, and had no influence on efficiency of the pasture to produce dry matter
per unit of N absorbed. The third study, of methodological character, aimed the
validation of indirect procedures for estimate the functional relation between the green
and dry mass and the LAI. The occurrence frequency and the index of green covering
were tested as substitutes of IAF using simple correlation procedure. Although in this
study has been observed the existence of a significant association among the the canopy
attributes estimates associated to the leaf area and the forage production leaf area and
forage production, additional studies are necessary to improve the reliability and
accuracy of this estimates. Finally, in the last study, the influence of the nitrogen
fertilization on nutritional value of the forage was evaluated. The crude protein, neutral
detergent fiber, acid detergent fiber, lignin, cellulose and hemicelulose cotents were
determined. The results showed that the addition of N improved the forage quality,
increasing crude protein contents and decreasing fibrous fraction.<br>Foram avaliados os efeitos da aplica??o de nitrog?nio (N) sobre uma s?rie de atributos
estruturais e nutricionais do dossel. Os estudos foram desenvolvidos no campo
experimental da Universidade Federal Rural do Rio de Janeiro, munic?pio de Serop?dica-
RJ, em ?rea de ocorr?ncia de Planossolo. O experimento foi conduzido sob regime de
cortes, durante o per?odo de outubro de 2006 a julho de 2007. Foram estudadas cinco doses
de N (0; 150; 300; 450 e 600 kg/ha) em diferentes ?pocas do ano. O experimento foi
conduzido em blocos inteiramente casualizados. Foram feitos quatro estudos, cujos
resultados s?o apresentados em cap?tulos distintos. No primeiro cap?tulo, os efeitos da
aduba??o nitrogenada s?o discutidos em termos de cobertura do solo, ?ndice de ?rea foliar e
intercepta??o da radia??o solar, no curso de quatro cortes seq?enciais, entre os meses de
fevereiro e julho. As avalia??es foram realizadas, semanalmente, entre o 10o e o 40o dia
ap?s o corte. Em cada corte, o ?ndice de ?rea foliar (IAF), a freq??ncia de ocorr?ncia, altura
de planta, ?ndice de cobertura verde e o n?vel de radia??o fotossinteticamente ativa
interceptada, responderam ? aduba??o nitrogenada, conforme um padr?o log?stico e
variaram sazonalmente, evidenciando uma sensibilidade diversa como indicadores da
estrutura e do crescimento da pastagem de Tifton 85. No segundo estudo foram abordadas
as respostas relativas ? produ??o de biomassa sob aduba??o nitrogenada e a efici?ncia na
utiliza??o do N absorvido. Para efeito de an?lise estat?stica, os dados das coletas foram
agrupados em ?poca das chuvas (fevereiro a abril) e ?poca seca (abril a julho). Em cada
data de corte foi quantificada a produ??o de massa verde e seca, a sua parti??o entre folhas
e colmos + bainhas, assim como o teor de N em cada uma das partes vegetativas. Este
estudo evidenciou que a aduba??o nitrogenada aumentou a produ??o de forragem,
estimulando a produ??o de folhas e colmos tanto na ?poca chuvosa quanto na seca. Por
outro lado, a aduba??o nitrogenada, per se, n?o modificou a parti??o da massa seca
produzida por folhas e colmos, nem influenciou a efici?ncia com a qual a pastagem produz
massa seca por unidade de nitrog?nio absorvido. O terceiro estudo, de cunho
metodol?gico, objetivou a valida??o de procedimentos indiretos para a estimativa da
rela??o funcional entre a massa verde e seca e o ?ndice de ?rea foliar da pastagem. Foram
estudados a freq??ncia de ocorr?ncia e o ?ndice de cobertura verde como suced?neos do
IAF, utilizando-se correla??o simples. Embora tenha sido observada a exist?ncia de um
grau de associa??o significativo entre as estimativas de atributos ligados ? ?rea foliar e a
produ??o de forragem, s?o necess?rios estudos adicionais para melhorar a confiabilidade e
a acur?cia de tais estimativas. No quarto estudo foi estudada a influencia da aduba??o
nitrogenada sobre o valor nutricional da forragem, sendo avaliados os teores de prote?na
bruta, fibra em detergente neutro, fibra em detergente ?cido, lignina, celulose e
hemicelulose. Os resultados obtidos mostraram que a adi??o de N melhorou a qualidade da
forragem, aumentando os teores de prote?na bruta e reduzindo a fra??o fibrosa.
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Klisch, Anja. "Ableitung von Blattflächenindex und Bedeckungsgrad aus Fernerkundungsdaten für das Erosionsmodell EROSION 3D." Phd thesis, Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2005/104/.
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In den letzten Jahren wurden relativ komplexe Erosionsmodelle entwickelt, deren Teilprozesse immer mehr auf physikalisch begründeten Ansätzen beruhen. Damit verbunden ist eine höhere Anzahl aktueller Eingangsparameter, deren Bestimmung im Feld arbeits- und kostenaufwendig ist. Zudem werden die Parameter punktuell, also an bestimmten Stellen und nicht flächenhaft wie bei der Fernerkundung, erfasst. <br />
<br />
Im Rahmen dieser Arbeit wird gezeigt, wie Satellitendaten als relativ kostengünstige Ergänzung oder Alternative zur konventionellen Parametererhebung genutzt werden können. Dazu werden beispielhaft der Blattflächenindex (LAI) und der Bedeckungsgrad für das physikalisch begründete Erosionsmodell EROSION 3D abgeleitet. Im Mittelpunkt des Interesses steht dabei das Aufzeigen von existierenden Methoden, die die Basis für eine operationelle Bereitstellung solcher Größen nicht nur für Erosions- sondern allgemein für Prozessmodelle darstellen. Als Untersuchungsgebiet dient das primär landwirtschaftlich genutzte Einzugsgebiet des Mehltheuer Baches, das sich im Sächsischen Lößgefilde befindet und für das Simulationsrechnungen mit konventionell erhobenen Eingangsparametern für 29 Niederschlagsereignisse im Jahr 1999 vorliegen [MICHAEL et al. 2000].<br />
<br />
Die Fernerkundungsdatengrundlage bilden Landsat-5-TM-Daten vom 13.03.1999, 30.04.1999 und 19.07.1999. Da die Vegetationsparameter für alle Niederschlagsereignisse vorliegen sollen, werden sie basierend auf der Entwicklung des LAI zeitlich interpoliert. Dazu erfolgt zunächst die Ableitung des LAI für alle vorhandenen Fruchtarten nach den semi-empirischen Modellen von CLEVERS [1986] und BARET & GUYOT [1991] mit aus der Literatur entnommenen Koeffizienten. Des Weiteren wird eine Methode untersucht, nach der die Koeffizienten für das Clevers-Modell aus den TM-Daten und einem vereinfachten Wachstumsmodell bestimmt werden. Der Bedeckungsgrad wird nach ROSS [1981] aus dem LAI ermittelt. Die zeitliche Interpolation des LAI wird durch die schlagbezogene Anpassung eines vereinfachten Wachstumsmodells umgesetzt, das dem hydrologischen Modell SWIM [KRYSANOVA et al. 1999] entstammt und in das durchschnittliche Tagestemperaturen eingehen. Mit den genannten Methoden bleiben abgestorbene Pflanzenteile unberücksichtigt. Im Vergleich zur konventionellen terrestrischen Parametererhebung ermöglichen sie eine differenziertere Abbildung räumlicher Variabilitäten und des zeitlichen Verlaufes der Vegetationsparameter.<br />
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Die Simulationsrechnungen werden sowohl mit den direkten Bedeckungsgraden aus den TM-Daten (pixelbezogen) als auch mit den zeitlich interpolierten Bedeckungsgraden für alle Ereignisse (schlagbezogen) durchgeführt. Bei beiden Vorgehensweisen wird im Vergleich zur bisherigen Abschätzung eine Verbesserung der räumlichen Verteilung der Parameter und somit eine räumliche Umverteilung von Erosions- und Depositionsflächen erreicht. Für die im Untersuchungsgebiet vorliegende räumliche Heterogenität (z. B. Schlaggröße) bieten Landsat-TM-Daten eine ausreichend genaue räumliche Auflösung. Damit wird nachgewiesen, dass die satellitengestützte Fernerkundung im Rahmen dieser Untersuchungen sinnvoll einsetzbar ist. Für eine operationelle Bereitstellung der Parameter mit einem vertretbaren Aufwand ist es erforderlich, die Methoden weiter zu validieren und möglichst weitestgehend zu automatisieren.<br>Soil erosion models become increasingly more complex and contain physically based components, resulting in changing requirements for their input parameters. The spatial and temporal dynamics of erosions forcing parameters thus produce high requirements on data availability (costs and manpower). Due to this fact, the use of complex erosion models for extensive regions is strongly limited by the high in-situ expense. Moreover, conventional measurement procedures provide parameters at certain points, while remote sensing is a two-dimensional retrieval method.<br />
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This thesis demonstrates, how satellite data can be used as a cost-effective supplementation or alternative to conventional measurement procedures. Leaf area index (LAI) and soil cover percentage are examplarily derived for the EROSION 3D physically based soil erosion model. The main objective of this study is to summarise existing retrieval methods in order to operationally provide such paramaters for soil erosion models or for process models in general. The methods are applied to a catchment in the loess region in Saxony (Germany), that predominantly is agriculturally used. For comparison, simulations based on conventionally estimated parameters for 29 rainstorm events are available [MICHAEL et al. 2000]. <br />
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The remote sensing parameters are derived from Landsat 5 TM data on the following dates: 13.03.1999, 30.04.1999, 19.07.1999. To get temporally continuous data for all events, they are interpolated between the acquisition dates based on the LAI development. Therefore, LAI is firstly calculated for all occurring crops by means of the semi-empirical models of CLEVERS [1986] and BARET & GUYOT [1991]. The coefficients appropriated to these models are taken from literature. Furthermore, a method is investigated that enables coefficient estimation for the Clevers model from Landsat data combined with a simplified growth model. Next, soil cover percentage is derived from LAI after ROSS [1981]. The LAI interpolation is performed by the simplified crop growth model from the SWIM hydrological model [Krysanova et al. 1999]. It has to be mentioned, that plant residue remains unconsidered by the used methods. In comparison to conventional measurement procedures, these methods supply a differentiated mapping of the spatial variability and temporal behaviour regarding the vegetation parameters.<br />
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The simulations with EROSION 3D are carried out for the remotely sensed soil cover percentages, that are retrieved in two ways. Soil cover is directly derived from the remote sensing data for each pixel at the acquisition dates as well as estimated by means of the interpolation for each field on all rainstorm events. In comparison to conventionally determined soil cover, both methods provide an improved spatial allocation of this parameter and thus, a spatial reallocation of erosion and deposition areas. The used Landsat Data provide an adequate spatial resolution suitable for the spatial heterogeneity given in the test area (e. g. field size). These results show that satellite based remote sensing can be reasonably used within the scope of these investigations. In the future, operational retrieval of such remotely sensed parameters necessitates the validation of the proposed methods and in general the automation of involved sub-processes to the greatest possible extent
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Mazumdar, Deepayan Dutta. "Multiangular crop differentiation and LAI estimation using PROSAIL model inversion." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, c2011, 2011. http://hdl.handle.net/10133/3103.
Texto completo da fonteResumo:
Understanding variations in remote sensing data with illumination and sensor angle changes is important in agricultural crop monitoring. This research investigated field bidirectional reflectance factor (BRF) in crop differentiation and PROSAIL leaf area index (LAI) estimation. BRF and LAI data were collected for planophile and erectophile crops at three growth stages. In the solar principal plane, BRF differed optimally at 860 nm 60 days after planting (DAP) for canola and pea, at 860 nm 45 and 60 DAP for wheat and barley, and at 860 nm and 670 nm 45 and 60 DAP for planophiles versus erectophiles. The field BRF data helped better understand PROSAIL LAI estimation. NDVI was preferred for estimating LAI, however the MTVI2 vegetation index showed high sensitivity to view angles, particularly for erectophiles. The hotspot was important for crop differentiation and LAI. Availability of more along-track, off-nadir looking spaceborne sensors was recommended for agricultural crop monitoring.<br>xiii, 161 leaves : ill., map ; 29 cm