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1
Streeks, Tamara J., M. Keith Owens, and Steve G. Whisenant. "Examining fire behavior in mesquite - acacia shrublands." International Journal of Wildland Fire 14, no. 2 (2005): 131. http://dx.doi.org/10.1071/wf03053.
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The vegetation of South Texas has changed from mesquite savanna to mixed mesquite–acacia (Prosopis–Acacia) shrubland over the last 150 years. Fire reduction, due to lack of fine fuel and suppression of naturally occurring fires, is cited as one of the primary causes for this vegetation shift. Fire behavior, primarily rate of spread and fire intensity, is poorly understood in these communities, so fire prescriptions have not been developed. We evaluated two current fire behavior systems (BEHAVE and the CSIRO fire spread and fire danger calculator) and three models developed for shrublands to determine how well they predicted rate of spread and flame length during three summer fires within mesquite–acacia shrublands. We also used geostatistical analyses to examine the spatial pattern of net heat, flame temperature and fuel characteristics. The CSIRO forest model under-predicted the rate of fire spread by an average of 5.43 m min−1 and over-predicted flame lengths by 0.2 m while the BEHAVE brush model under-predicted rate of spread by an average of 6.57 m min−1 and flame lengths by an average of 0.33 m. The three shrubland models did not consistently predict the rate of spread in these plant communities. Net heat and flame temperature were related to the amount of 10-h fuel on the site, but were not related to the cover of grasses, forbs, shrubs, or apparent continuity of fine fuel. Fuel loads were typical of South Texas shrublands, in that they were uneven and spatially inconsistent, which resulted in an unpredictable fire pattern.
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Schrader-Patton, Charlie C., and Emma C. Underwood. "New Biomass Estimates for Chaparral-Dominated Southern California Landscapes." Remote Sensing 13, no. 8 (April 19, 2021): 1581. http://dx.doi.org/10.3390/rs13081581.
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Chaparral shrublands are the dominant wildland vegetation type in Southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrublands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict aboveground live biomass in Southern California using remote sensing data (Landsat Normalized Difference Vegetation Index (NDVI)) and a suite of geophysical variables. By substituting the NDVI and precipitation predictors for any given year, we were able to apply the model to each year from 2000 to 2019. Using a total of 980 field plots, our model had a k-fold cross-validation R2 of 0.51 and an RMSE of 3.9. Validation by vegetation type ranged from R2 = 0.17 (RMSE = 9.7) for Sierran mixed-conifer to R2 = 0.91 (RMSE = 2.3) for sagebrush. Our estimates showed an improvement in accuracy over two other biomass estimates that included shrublands, with an R2 = 0.82 (RMSE = 4.7) compared to R2 = 0.068 (RMSE = 6.7) for a global biomass estimate and R2 = 0.29 (RMSE = 5.9) for a regional biomass estimate. Given the importance of accurate biomass estimates for resource managers, we calculated the mean year 2010 shrubland biomasses for the four national forests that ranged from 3.5 kg/m2 (Los Padres) to 2.3 kg/m2 (Angeles and Cleveland). Finally, we compared our estimates to field-measured biomasses from the literature summarized by shrubland vegetation type and age class. Our model provides a transparent and repeatable method to generate biomass measurements in any year, thereby providing data to track biomass recovery after management actions or disturbances such as fire.
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Fernández-Guisuraga, José Manuel, Leonor Calvo, Paulo M. Fernandes, and Susana Suárez-Seoane. "Short-Term Recovery of the Aboveground Carbon Stock in Iberian Shrublands at the Extremes of an Environmental Gradient and as a Function of Burn Severity." Forests 13, no. 2 (January 19, 2022): 145. http://dx.doi.org/10.3390/f13020145.
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The degree to which burn severity influences the recovery of aboveground carbon density (ACD) of live pools in shrublands remains unclear. Multitemporal LiDAR data was used to evaluate ACD recovery three years after fire in shrubland ecosystems as a function of burn severity immediately after fire across an environmental and productivity gradient in the western Mediterranean Basin. Two large mixed-severity wildfires were assessed: an Atlantic site, dominated by resprouter shrubs and located at the most productive extreme of the gradient, and a Mediterranean site, dominated by obligate seeders and located at the less productive extreme. Initial assessment of burn severity was performed using the differenced Normalized Burn Ratio index computed from Landsat imagery. Thresholds for low and high burn severity categories were established using the Composite Burn Index (CBI). LiDAR canopy metrics were calibrated with field measurements of mean shrub height and cover at plot level in a post-fire situation. Pre-fire and post-fire ACD estimates, and their ratio (ACDr) to calculate carbon stock recovery, were computed from the predictions of LiDAR grid metrics at landscape level using shrubland allometric relationships. Overall, ACDr decreased both with high burn severity and low productivity, although the burn severity impact was not homogeneous within the gradient. In the Atlantic site, ACDr was similar under low and high burn severity, whereas it decreased with burn severity in the Mediterranean site. These results suggest that carbon cycling models could be biased by not accounting for both fire severity and species composition of shrublands under different environmental conditions.
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Pearce, H. G., W. R. Anderson, L. G. Fogarty, C. L. Todoroki, and S. A. J. Anderson. "Linear mixed-effects models for estimating biomass and fuel loads in shrublands." Canadian Journal of Forest Research 40, no. 10 (October 2010): 2015–26. http://dx.doi.org/10.1139/x10-139.
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Shrubland biomass is important for fire management programmes and for carbon estimates. Aboveground biomass and the combustible portion of biomass, the fuel load, in the past have been measured using destructive techniques. These techniques are detailed, highly labour intensive, and costly; hence, an alternative approach was sought. The new approach used linear mixed-effects models to estimate biomass and fuel loads from easily measured field variables: shrub overstorey height and cover, and understorey height and cover. Site was regarded as a random effect. Sampling sites were located throughout New Zealand and included a range of shrubland vegetation types: manuka ( Leptospermum scoparium J.R. Forst. et G. Forst.) and kanuka ( Kunzea ericoides (A. Rich.) J. Thomps.) scrub and heath, pakihi (mixed low heath, fern, and rushes), and gorse ( Ulex europaeus L.). The approach was extended and confidence intervals were constructed for the regression models. Statistical analysis showed that understorey height and overstorey cover were significant (at the 5% level) in some cases. Overstorey height was highly significant in all cases (p < 0.0001), allowing development of models useful to the operational user. The models allow rapid estimation of average fuel loads or biomass on new sites, and double sampling theory can be applied to calculate the error in the resultant biomass estimate.
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Costa-Saura, José M., Ángel Balaguer-Beser, Luis A. Ruiz, Josep E. Pardo-Pascual, and José L. Soriano-Sancho. "Empirical Models for Spatio-Temporal Live Fuel Moisture Content Estimation in Mixed Mediterranean Vegetation Areas Using Sentinel-2 Indices and Meteorological Data." Remote Sensing 13, no. 18 (September 17, 2021): 3726. http://dx.doi.org/10.3390/rs13183726.
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Live fuel moisture content (LFMC) is an input factor in fire behavior simulation models highly contributing to fire ignition and propagation. Developing models capable of accurately estimating spatio-temporal changes of LFMC in different forest species is needed for wildfire risk assessment. In this paper, an empirical model based on multivariate linear regression was constructed for the forest cover classified as shrublands in the central part of the Valencian region in the Eastern Mediterranean of Spain in the fire season. A sample of 15 non-monospecific shrubland sites was used to obtain a spatial representation of this type of forest cover in that area. A prediction model was created by combining spectral indices and meteorological variables. This study demonstrates that the Normalized Difference Moisture Index (NDMI) extracted from Sentinel-2 images and meteorological variables (mean surface temperature and mean wind speed) are a promising combination to derive cost-effective LFMC estimation models. The relationships between LFMC and spectral indices for all sites improved after using an additive site-specific index based on satellite information, reaching a R2adj = 0.70, RMSE = 8.13%, and MAE = 6.33% when predicting the average of LFMC weighted by the canopy cover fraction of each species of all shrub species present in each sampling plot.
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Poulos, Helen M., Michael R. Freiburger, Andrew M. Barton, and Alan H. Taylor. "Mixed-Severity Wildfire as a Driver of Vegetation Change in an Arizona Madrean Sky Island System, USA." Fire 4, no. 4 (October 20, 2021): 78. http://dx.doi.org/10.3390/fire4040078.
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Fire is a powerful natural disturbance influencing vegetation patterns across landscapes. Recent transitions from mixed-species forests to post-fire shrublands after severe wildfire is an increasingly prevalent phenomenon in pine-oak and conifer forest ecosystems in southwestern North America. However, we know little about how variation in fire severity influences other common forest types in the region. In this study, we evaluated fire-induced changes in woody plant community composition and forest structure in Chiricahua Mountains in southeastern Arizona in the United States that hosts a diverse set of vegetation types. Cluster analysis of the pre-fire vegetation data identified three dominant pre-fire vegetation types including juniper woodland, piñon forest, and pine-oak forest. All vegetation types experienced significant tree mortality across a wide range of size classes and species, from forests to shrublands. The magnitude of change within sample plots varied with fire severity, which was mediated by topography. Significant shifts in dominance away from coniferous obligate seeder trees to resprouting hardwoods and other shrubs occurred across all vegetation types in response to the fire. Regeneration from seed can be episodic, but projected increases in aridity and fire frequency may promote continued dominance by hardwoods and fire- and drought-resistant shrub communities, which is a regional forest management concern as wildfire size and severity continue to increase throughout the southwestern USA.
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Gartzia, Maite, Concepción L. Alados, and Fernando Pérez-Cabello. "Assessment of the effects of biophysical and anthropogenic factors on woody plant encroachment in dense and sparse mountain grasslands based on remote sensing data." Progress in Physical Geography: Earth and Environment 38, no. 2 (April 2014): 201–17. http://dx.doi.org/10.1177/0309133314524429.
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Land abandonment exacerbated by climate change has led to increased woody plant encroachment of mountain grasslands in many regions of the world. The present study assessed woody plant encroachment below potential tree line in the Central Pyrenees of Spain and the association of this encroachment with changes in land use. Remote sensing data from Landsat-5 Thematic Mapper (TM) from the mid-1980s and mid-2000s were analyzed by supervised classification for identification of land cover types. The transition matrix indicated that shrublands were the most dynamic plant communities. Consequently, 21% of cultivated areas, 19% of dense grasslands, and 24% of sparse grasslands became shrublands during the period analyzed, and 35% of shrublands became forest. Generalized additive mixed models (GAMMs) were used to identify biophysical and anthropogenic factors that were significantly correlated with woody plant encroachment of dense and sparse grasslands. Distance to the nearest woody plant habitat (shrub or forest) was the most strongly correlated factor with woody plant encroachment of both types of grassland. This factor explained 69% and 71% of the variance in models of dense and sparse grasslands, respectively. Besides this factor, anthropogenic factors had larger effects on woody plant encroachment of dense grasslands, regions that were more productive and accessible. However, biophysical and especially topographic factors had slightly greater effects on woody plant encroachment of sparse grasslands, regions that were less productive and accessible. The changes in land cover that we observed indicated that land cover has become more homogeneous. There have been reductions in the variety, functions, and services of grasslands, particularly in areas below the potential tree line that are vulnerable to the development of woody plant habitats.
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García, Miguel, Hassane Moutahir, Grant Casady, Susana Bautista, and Francisco Rodríguez. "Using Hidden Markov Models for Land Surface Phenology: An Evaluation Across a Range of Land Cover Types in Southeast Spain." Remote Sensing 11, no. 5 (March 2, 2019): 507. http://dx.doi.org/10.3390/rs11050507.
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Land Surface Phenology (LSP) metrics are increasingly being used as indicators of climate change impacts in ecosystems. For this purpose, it is necessary to use methods that can be applied to large areas with different types of vegetation, including vulnerable semiarid ecosystems that exhibit high spatial variability and low signal-to-noise ratio in seasonality. In this work, we evaluated the use of hidden Markov models (HMM) to extract phenological parameters from Moderate Resolution Imaging Spectroradiometer (MODIS) derived Normalized Difference Vegetation Index (NDVI). We analyzed NDVI time-series data for the period 2000–2018 across a range of land cover types in Southeast Spain, including rice croplands, shrublands, mixed pine forests, and semiarid steppes. Start of Season (SOS) and End of Season (EOS) metrics derived from HMM were compared with those obtained using well-established smoothing methods. When a clear and consistent seasonal variation was present, as was the case in the rice croplands, and when adjusting average curves, the smoothing methods performed as well as expected, with HMM providing consistent results. When spatial variability was high and seasonality was less clearly defined, as in the semiarid shrublands and steppe, the performance of the smoothing methods degraded. In these cases, the results from HMM were also less consistent, yet they were able to provide pixel-wise estimations of the metrics even when comparison methods did not.
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Tarasova, L. V., and L. N. Smirnova. "Satellite-based analysis of classification algorithms applied to the riparian zone of the Malaya Kokshaga river." IOP Conference Series: Earth and Environmental Science 932, no. 1 (December 1, 2021): 012012. http://dx.doi.org/10.1088/1755-1315/932/1/012012.
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Abstract The paper comparatively analyses the accuracy of land cover classification in the riparian zone of the Malaya Kokshaga river in the Mari El Republic of Russia using Sentinel-2A satellite images with the algorithms of supervised classification: Maximum Likelihood (ML), Decision Tree (DT) and Neural Net (NN) in the ENVI-5.2 software package. Six main classes of land cover were identified based on field studies: coniferous, mixed (deciduous), shrublands, herbaceous, and water. The assessment of the area and the structure of land cover showed that forest covers 76% of the entire territory of the riparian area of the Malaya Kokshaga river. The analysis of the results of thematic mapping shows that the overall classification accuracy obtained by the ML algorithm is 96.09%, by NN - 94.51%, and by DT - 86.54%. The producer’s accuracy and user’s accuracy for most classes have the maximum value when the ML algorithm is used. For the NN algorithm, the maximum value of producer’s accuracy is observed for the mixed (deciduous) class, while for the DT algorithm – for the coniferous. When classified using all three algorithms the water and bare land classes were mixed, which requires more detailed work when estimating riparian forest ecosystems.
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Alt, Mio, David B. McWethy, Rick Everett, and Cathy Whitlock. "Millennial scale climate-fire-vegetation interactions in a mid-elevation mixed coniferous forest, Mission Range, northwestern Montana, USA." Quaternary Research 90, no. 1 (May 8, 2018): 66–82. http://dx.doi.org/10.1017/qua.2018.25.
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AbstractMixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over the last 15,000 years. These data suggest an open parkland and minimal fire activity before 13,500 cal yr BP, consistent with cold, dry conditions. Increases inPinuspollen after 13,500 cal yr BP indicate a transition to closed forests, and a slight rise in fire activity as conditions warmed and fuel biomass increased. High levels ofArtemisiapollen between 10,000 and 6000 cal yr BP suggest an open forest during the early Holocene when conditions were warmer and drier than present. Low-severity fires likely maintained open forest/shrublands but produced little charcoal during this interval. Present-day mixed-coniferous forests were established in the last 6 ka and included forest taxa characteristic of low- (Pseudotsuga-Larix/Pinus ponderosa)and high-severity fire regimes (Picea/Abies). Increased climate variability and anthropogenic burning may have helped maintain heterogeneous, mixed-coniferous forests during the last several millennia when climate conditions became cooler and wetter.
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Lambie, S. M., and J. Dando. "Seasonal litterfall composition and carbon and nitrogen returns in New Zealand shrubland." Australian Journal of Botany 67, no. 8 (2019): 610. http://dx.doi.org/10.1071/bt19070.
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Mānuka–kānuka shrubland is an important carbon (C) sink in New Zealand, yet little is known about C cycling within these systems. The objective of our work was to assess seasonal litterfall rates, composition, and C and nitrogen (N) inputs in mixed mānuka (Leptospermum scoparium J.R. Forst & G. Forst.) and kānuka (Kunzea ericoides var. ericoides (A.Rich) J.Thompson) stands. Litterfall was collected for 2years at Tongariro National Park (NP) and Stoney Creek, Wairarapa (SC), separated into leaf, twig, bark, seed and ‘other’, and the C and N content of each component measured. Total litterfall was between 3557 and 4443kgha–1year–1, of which leaf material contributed 46–67%. Litterfall peaked during spring–summer months at both sites, and the overall litterfall rate was greater (P < 0.001) at SC than NP. Litterfall at SC contained greater (P < 0.001) amounts of ‘other’ due to higher undergrowth contributions, and also greater seed fall (P < 0.001), possibility due to the lower altitude at SC. The proportion of leaf material in litterfall also peaked during summer (P < 0.001). C inputs in the total litter were 1941–2448kgCha–1year–1 and N inputs ranged between 28 and 37kgNha–1year–1. There was little seasonal difference in C and N contents and the majority of both C and N inputs in litterfall were in the leaf material (P < 0.001). C inputs peaked during summer, but N inputs were closely aligned with total litterfall maximums during spring–summer. The leaf:wood ratio was 1.9 at both sites, indicating litter quality was consistent at both stands, regardless of differences in composition. Although the sites had similar rainfall and shrub ages, the rate of total litterfall differed, reflecting the potentially site-specific nature of litterfall in mānuka–kānuka shrubland. Further work is needed assessing litterfall and degradation rates across New Zealand to establish if mānuka–kānuka shrublands would remain carbon sinks under climate change.
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Celaya, Rafael, Luis M. M. Ferreira, José M. Lorenzo, Noemí Echegaray, Santiago Crecente, Emma Serrano, and Juan Busqué. "Livestock Management for the Delivery of Ecosystem Services in Fire-Prone Shrublands of Atlantic Iberia." Sustainability 14, no. 5 (February 26, 2022): 2775. http://dx.doi.org/10.3390/su14052775.
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In the northwest of the Iberian Peninsula, characterized by its humid climate, large rural areas are being abandoned, mostly in less-favoured areas covered by heathlands, which present a low nutritive quality for livestock production. The high combustibility of these shrublands is driving a high wildfire incidence with negative environmental and economic effects. In this review, some aspects on wildfire occurrence and the potential of grazing livestock to reduce woody phytomass and fire risk in heathland-dominated areas whilst maintaining quality production and preserving biodiversity are summarized. Heathlands may be partially improved—converted to grassland—to better meet animals’ nutritional requirements while acting as ‘natural’ firebreaks. The specific grazing behaviour offers the opportunity to combine different domestic herbivores (mixed grazing) to achieve sustainable systems utilizing heterogeneous resources. Cattle, sheep, goats, and horses may have a role in the provision of different ecosystem services such as food production and biodiversity conservation. Genotype x environment interactions shape the ability of animals to cope with poor vegetation conditions, with smaller species and breeds performing better than larger animals. Goats and horses are indicated to arrest woody encroachment. Sustainable grazing systems are affordable in heathland–grassland mosaics by selecting appropriate livestock species and breeds for quality production, thus favouring rural economies and lowering fire risk.
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Yocom, Larissa L., Jeff Jenness, Peter Z. Fulé, and Andrea E. Thode. "Fire Severity in Reburns Depends on Vegetation Type in Arizona and New Mexico, U.S.A." Forests 13, no. 11 (November 19, 2022): 1957. http://dx.doi.org/10.3390/f13111957.
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After more than a century of low fire activity in the western United States, wildfires are now becoming more common. Reburns, which are areas burned in two or more fires, are also increasing. How fires interact over time is of interest ecologically as well as for management. Wildfires may act as fuel treatments, reducing subsequent fire severity, or they may increase subsequent fire severity by leaving high fuel loads behind. Our goal was to assess whether previous wildfire severity influenced subsequent fire severity across vegetation types and over time in the Southwest U.S. using remotely sensed fire severity data in 2275 fires that burned between 1984 and 2019. Points that reburned tended to be those that burned with lower severity initially. Shrublands burned predominantly at moderate to high severity in initial fires and in reburns. Pinyon-juniper-oak systems burned with mixed severity, and fire severity was consistent from fire to fire. In ponderosa pine and aspen-mixed conifer, fire severity tended to decrease with each fire. Initial and subsequent fire severity was lower in points that reburned after a short interval. These remotely sensed observations of reburn severity need verification through field work to understand specific effects caused by reburns in different ecosystems. However, in ponderosa pine and aspen-mixed conifer forests, it may be beneficial to consider wildfires as fuel treatments and work to maintain the fuel reduction effects they have on forested ecosystems.
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MACIOROWSKI, GRZEGORZ, and PAWEŁ MIRSKI. "Habitat alteration enables hybridisation between Lesser Spotted and Greater Spotted Eagles in north-east Poland." Bird Conservation International 24, no. 2 (August 28, 2013): 152–61. http://dx.doi.org/10.1017/s0959270913000348.
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SummaryWetlands in the Biebrza Valley, north-east Poland, are inhabited by two closely related Aquila species: the more numerous Lesser Spotted Eagle A. pomarina prefers human-transformed landscapes, whereas the very rare Greater Spotted Eagle A. clanga is associated with natural marshy landscapes. At least since the last decade of the 20th century, these two species have been known to hybridise in the broad zone of their sympatric occurrence in Europe. The aim of the present study was to compare habitat preferences of both spotted eagle species in order to detect which environmental factors could increase the probability of hybridisation. We analysed nesting and hunting habitats for 148 breeding territories (61 of A. pomarina, 56 of A. clanga and 31 of mixed pairs). As expected, the presence of breeding Greater Spotted Eagles was associated with non-transformed marshy landscapes, whereas Lesser Spotted Eagles clearly preferred human-transformed areas. We hypothesised that mixed pairs should occur in intermediate habitat, confirming this assumption by analysing several variables: distance to human settlements, distance to open areas, and proportion of wetlands, shrublands, grasslands, agricultural mosaic and arable land. Results of this study suggest that some landscape changes can enable two species with different habitat requirements to inhabit the same area and hybridise. This scenario has potential conservation implications for the rarer species, Greater Spotted Eagle, which has narrower habitat preferences.
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Qiu, Ruonan, Ge Han, Xin Ma, Hao Xu, Tianqi Shi, and Miao Zhang. "A Comparison of OCO-2 SIF, MODIS GPP, and GOSIF Data from Gross Primary Production (GPP) Estimation and Seasonal Cycles in North America." Remote Sensing 12, no. 2 (January 11, 2020): 258. http://dx.doi.org/10.3390/rs12020258.
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Remotely sensed products are of great significance to estimating global gross primary production (GPP), which helps to provide insight into climate change and the carbon cycle. Nowadays, there are three types of emerging remotely sensed products that can be used to estimate GPP, namely, MODIS GPP (Moderate Resolution Imaging Spectroradiometer GPP, MYD17A2H), OCO-2 SIF, and GOSIF. In this study, we evaluated the performances of three products for estimating GPP and compared with GPP of eddy covariance(EC) from the perspectives of a single tower (23 flux towers) and vegetation types (evergreen needleleaf forests, deciduous broadleaf forests, open shrublands, grasslands, closed shrublands, mixed forests, permeland wetlands, and croplands) in North America. The results revealed that sun-induced chlorophyll fluorescence (SIF) data and MODIS GPP data were highly correlated with the GPP of flux towers (GPPEC). GOSIF and OCO-2 SIF products exhibit a higher accuracy in GPP estimation at the a single tower (GOSIF: R2 = 0.13–0.88, p < 0.001; OCO-2 SIF: R2 = 0.11–0.99, p < 0.001; MODIS GPP: R2 = 0.15–0.79, p < 0.001). MODIS GPP demonstrates a high correlation with GPPEC in terms of the vegetation type, but it underestimates the GPP by 1.157 to 3.884 gCm−2day−1 for eight vegetation types. The seasonal cycles of GOSIF and MODIS GPP are consistent with that of GPPEC for most vegetation types, in spite of an evident advanced seasonal cycle for grasslands and evergreen needleleaf forests. Moreover, the results show that the observation mode of OCO-2 has an evident impact on the accuracy of estimating GPP using OCO-2 SIF products. In general, compared with the other two datasets, the GOSIF dataset exhibits the best performance in estimating GPP, regardless of the extraction range. The long time period of MODIS GPP products can help in the monitoring of the growth trend of vegetation and the change trends of GPP.
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Zhao, Cailing, Chongshui Gong, Haixia Duan, Pengcheng Yan, Yuanpu Liu, and Ganlin Zhou. "Evaluation of Three Reanalysis Soil Temperature Datasets with Observation Data over China." Earth 3, no. 4 (October 11, 2022): 1042–58. http://dx.doi.org/10.3390/earth3040060.
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Soil temperature is a crucial parameter in surface emissions of carbon, water, and energy exchanges. This study utilized the soil temperature of 836 national basic meteorological observing stations over China to evaluate three soil temperature products. Soil temperature data from the China Meteorology Administration Land Data Assimilation System (CLDAS), European Centre for Medium-Range Weather Forecasts (ERA-Interim), and Global Land Data Assimilation System (GLDAS) during 2017 are evaluated. The results showed that soil temperature reanalysis datasets display a significant north-to-south difference over eastern China with generally underestimated magnitudes. CLDAS data perform soil temperature assessment best at different depths and can be reproduced well in most areas of China. CLDAS slightly overestimates soil temperature in summer. The most significant deviation of ERA-Interim (GLDAS) appears in summer (summer and autumn). As soil depth increases, the soil temperature errors of all three datasets increase. The CLDAS represents the soil temperature over China but owns a more considerable bias in barren or sparsely vegetated croplands. ERA-Interim performs poorest in urban and built-up and barren or sparsely vegetated areas. GLDAS overall owns an enormous bias at the mixed forest, grassland, and croplands areas, which should be improved, especially in summer. However, it performs better in open shrublands and barren or sparsely vegetated areas. The ST of mixed forests shows better results in the south region than the north region. For grasslands, smaller MEs are located in the north and northwest regions. The ST of croplands shows the poorest performance over the northwest region.
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Wood, David J. A., Todd M. Preston, Scott Powell, and Paul C. Stoy. "Multiple UAV Flights across the Growing Season Can Characterize Fine Scale Phenological Heterogeneity within and among Vegetation Functional Groups." Remote Sensing 14, no. 5 (March 6, 2022): 1290. http://dx.doi.org/10.3390/rs14051290.
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Grasslands and shrublands exhibit pronounced spatial and temporal variability in structure and function with differences in phenology that can be difficult to observe. Unpiloted aerial vehicles (UAVs) can measure vegetation spectral patterns relatively cheaply and repeatably at fine spatial resolution. We tested the ability of UAVs to measure phenological variability within vegetation functional groups and to improve classification accuracy at two sites in Montana, U.S.A. We tested four flight frequencies during the growing season. Classification accuracy based on reference data increased by 5–10% between a single flight and scenarios including all conducted flights. Accuracy increased from 50.6% to 61.4% at the drier site, while at the more mesic/densely vegetated site, we found an increase of 59.0% to 64.4% between a single and multiple flights over the growing season. Peak green-up varied by 2–4 weeks within the scenes, and sparse vegetation classes had only a short detectable window of active phtosynthesis; therefore, a single flight could not capture all vegetation that was active across the growing season. The multi-temporal analyses identified differences in the seasonal timing of green-up and senescence within herbaceous and sagebrush classes. Multiple UAV measurements can identify the fine-scale phenological variability in complex mixed grass/shrub vegetation.
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Gaiotti, Milene G., Michael S. Webster, and Regina H. Macedo. "An atypical mating system in a neotropical manakin." Royal Society Open Science 7, no. 1 (January 2020): 191548. http://dx.doi.org/10.1098/rsos.191548.
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Most of the diversity in the mating systems of birds and other animals comes at higher taxonomic levels, such as across orders. Although divergent selective pressures should lead to animal mating systems that diverge sharply from those of close relatives, opportunities to examine the importance of such processes are scarce. We addressed this issue using the Araripe manakin ( Antilophia bokermanni ), a species endemic to a forest enclave surrounded by xeric shrublands in Brazil. Most manakins exhibit polygynous lekking mating systems that lack territoriality but exhibit strong sexual selection. In sharp contrast, we found that male Araripe manakins defended exclusive territories, and females nested within male territories. However, territoriality and offspring paternity were dissociated: males sired only 7% of nestlings from the nests within their territories and non-territorial males sired numerous nestlings. Moreover, female polyandry was widespread, with most broods exhibiting mixed paternity. Apparently, territories in this species function differently from both lekking arenas and resource-based territories of socially monogamous species. The unexpected territoriality of Araripe manakins and its dissociation from paternity is a unique evolutionary development within the manakin clade. Collectively, our findings underscore how divergences in mating systems might evolve based on selective pressures from novel environmental contexts.
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CORLETT, RICHARD T. "Pollination in a degraded tropical landscape: a Hong Kong case study." Journal of Tropical Ecology 17, no. 1 (January 2001): 155–61. http://dx.doi.org/10.1017/s0266467401001109.
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Although the pollination biology of many individual plant species has been investigated in the Oriental region, there have been very few community-level studies. The two most comprehensive of these were in the primary mixed dipterocarp forest of Lambir Hills National Park, Sarawak (4°20′N: Momose et al. 1998, Sakai et al. 1999) and in the warm temperate evergreen broad-leaved forest and cool temperate mixed forest on Yakushima Island (30°N: Yumoto 1987, 1988). Hong Kong (22°17′N) lies midway between these sites, at the northern margin of the tropics, where winter temperatures fall below 10 °C at sea-level for a few days every year and there are occasional frosts above 400 m (Dudgeon & Corlett 1994). Latitudinal effects, however, are compounded in comparisons with other well-studied East Asian sites, by centuries of massive human impact, leaving a degraded landscape of steep, eroded hillsides, covered in fire-maintained grassland, secondary shrublands and, locally, secondary forests (Zhuang & Corlett 1997). This history has left a relatively impoverished fauna but a surprisingly diverse flora, including 400 native tree species (Corlett & Turner 1997). In these circumstances, failures of pollination and dispersal mutualisms might be expected to accelerate the loss of plant species from the landscape (Bond 1994, Kearns & Inouye 1997). Previous studies have shown that most woody vegetation in Hong Kong is dominated by species whose seeds can be dispersed by the commonest avian frugivores, the light-vented and red-whiskered bulbuls (Pycnonotus sinensis (Gmelin) and P. jocosus (Linn.)) and the Japanese white-eye (Zosterops japonicus Swinhoe) (Corlett 1996, 1998), but there is no equivalent information available on pollination biology.
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Curt, Thomas, Aissa Aini, and Sylvain Dupire. "Fire Activity in Mediterranean Forests (The Algerian Case)." Fire 3, no. 4 (September 30, 2020): 58. http://dx.doi.org/10.3390/fire3040058.
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Algeria has high wildfire activity, albeit restricted to the northern coastal fringe. However, no study has investigated why fire is restricted to that area, and what combination of factors explains the occurrence of wildfires. Here, we describe the current fire regime of Northern Algeria from 2000 to 2019 and we correlate fire activity to a range of environmental and anthropic drivers. We found a strong north–south gradient in fire occurrence: it is maximal in the high-fueled (productive) oak forests of Northern Algeria with high annual rainfall amount, whereas it is fuel-limited in the South due to semi-arid conditions. We determined that fire is nearly absent where the bioclimate is subarid or arid, due to the steppic vegetation with summer Normalized Difference Vegetation Index (NDVI) values below 0.35. Therefore, fire occupies a narrow niche in space (the humid and subhumid areas with high productivity) and in time as most fires occur in summer after the high rainfalls from fall to spring that promote fuel growth. Humans also play a role as fire hotspots are concentrated in croplands and in built-up areas with high human density and infrastructures mixed with shrublands and forests. We discuss how the ongoing climate changes and the desertification progressing towards the North of Algeria may finally restrict forests to a narrow fringe providing less and less ecological services to the Algerian people.
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Gong, Haibo, Li Cao, Fusheng Jiao, Huiyu Liu, Mingyang Zhang, Jialin Yi, and Xiaojuan Xu. "Increasing Atmospheric Aridity Moderates the Accelerated Rate of Vegetation Green-Up Induced by Rising CO2 and Warming." Remote Sensing 14, no. 16 (August 14, 2022): 3946. http://dx.doi.org/10.3390/rs14163946.
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The rate of vegetation green-up (RVG) indicates the ability of vegetation to respond to changes in climatic conditions. Understanding long-term RVG trends can clarify the changes in how quickly the vegetation grows from dormancy to maturity with time. However, how RVG trends respond to environmental variables and variable interactions remains unknown. We examined the long-term RVG trends (1981–2018) over the northern extratropics and determined the influence of environment variables and interactions between variables on the RVG trends based on the Global Land Surface Satellite leaf area index and a multivariable regression considering interactions between variables (MRCI). Our results showed a persistent increase in RVG at 0.020% (8-day)−1 year−1 over the entire region. Except for shrublands (−0.032% (8-day)−1 year−1), RVG trends increased significantly, particularly in woody savannas (0.095% (8-day)−1 year−1) and mixed forests (0.076% (8-day)−1 year−1). The relative importance of interactive effects (RIIAE) to the RVG trends is roughly 30%. Rising CO2, enhanced vapor pressure deficit (VPD), and warming are the primary factors affecting the RVG trends, both at the pixel and the biome scales. The accelerated RVG is triggered by both rising CO2 and warming but is partially offset by increased VPD. Our findings shed light on the relative contribution of variable interactions and assessed the relationship between environmental factors and RVG trends across different biomes, hence strengthening our knowledge of vegetation spring green-up in response to global change.
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Williams, Jennifer M., Donald J. Brown, and Petra B. Wood. "Responses of Terrestrial Herpetofauna to Persistent, Novel Ecosystems Resulting from Mountaintop Removal Mining." Journal of Fish and Wildlife Management 8, no. 2 (July 1, 2017): 387–400. http://dx.doi.org/10.3996/102016-jfwm-079.
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Abstract Mountaintop removal mining is a large-scale surface mining technique that removes entire floral and faunal communities, along with soil horizons located above coal seams. In West Virginia, the majority of this mining occurs on forested mountaintops. However, after mining ceases the land is typically reclaimed to grasslands and shrublands, resulting in novel ecosystems. In this study, we examined responses of herpetofauna to these novel ecosystems 10–28 y postreclamation. We quantified differences in species-specific habitat associations, (sub)order-level abundances, and habitat characteristics in four habitat types: reclaimed grassland, reclaimed shrubland, forest fragments in mined areas, and nonmined intact forest. Habitat type accounted for 33.2% of the variation in species-specific captures. With few exceptions, forest specialists were associated with intact forest and fragmented forest sites, while habitat generalists were either associated with grassland and shrubland sites or were distributed among all habitat types. At the (sub)order level, salamander (Order Urodela) captures were highest at fragmented and intact forest sites, frog and toad (Order Anura) captures were lowest at intact forest sites, and snake (Suborder Serpentes) captures were highest at shrubland sites. Habitat type was a strong predictor for estimated total abundance of urodeles, but not for anurans or snakes. Tree stem densities in grasslands differed from the other three habitat types, and large trees (>38 cm diameter at breast height) were only present at forest sites. Overstory vegetation cover was greater in forested than in reclaimed habitat types. Ground cover in reclaimed grasslands was distinct from forest treatments with generally less woody debris and litter cover and more vegetative cover. It is important to consider the distributions of habitat specialists of conservation concern when delineating potential mountaintop mine sites, as these sites will likely contain unsuitable habitat for forest specialists for decades or centuries when reclaimed to grassland or shrubland.
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Senn, Carolina, Willy Tinner, Vivian A. Felde, Erika Gobet, Jacqueline FN van Leeuwen, and César Morales-Molino. "Modern pollen – vegetation – plant diversity relationships across large environmental gradients in northern Greece." Holocene 32, no. 3 (November 27, 2021): 159–73. http://dx.doi.org/10.1177/09596836211060494.
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Past vegetation and biodiversity dynamics, reconstructed using palaeoecological methods, can contribute to assessing the magnitude of the current biodiversity crisis and anticipating future risks and challenges. Among the different palaeoecological techniques, pollen analysis is probably the most widely used to reconstruct vegetation and plant diversity changes through time. Such reconstructions demand robust and comprehensive calibration studies addressing the pollen representation of extant vegetation to be sound. However, calibration studies are rare in the Mediterranean biodiversity hotspot, particularly regarding plant diversity. Here, we contribute to filling this gap by investigating the modern pollen signature of Mediterranean vegetation across a large environmental gradient in northern Greece. At each sampling site ( n = 61), we quantitatively compared the composition and diversity of plant (vegetation surveys) and pollen assemblages (moss/topsoil samples) using numerical techniques. Further, we compared these terrestrial pollen assemblages with those from lake sediment surface samples of the same region. We found an overall good match between plant and pollen assemblages, with maquis and mixed deciduous forest displaying particularly distinct pollen signatures. In contrast, the high regional importance of pines and oaks and their large pollen production blurred the pollen representation of other forested vegetation types and of shrublands and grasslands. Plant and pollen richness and their evenness showed similar declining trends with increasing altitude, but plant and pollen evenness bore a better match than richness. A more detailed vegetation-specific view on the data suggests that pine pollen seriously affected pollen richness and evenness in most of the pine-dominated stands. Lastly, our results suggest a rather straightforward application of vegetation-pollen relationships from moss/topsoil samples to interpret pollen assemblages from lakes in Mediterranean settings.
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Henry, B. K., D. Butler, and S. G. Wiedemann. "Quantifying carbon sequestration on sheep grazing land in Australia for life cycle assessment studies." Rangeland Journal 37, no. 4 (2015): 379. http://dx.doi.org/10.1071/rj14109.
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The sheep industry has played an important role in Australia’s development and economy over the 220 years since European settlement and remains an important land use in Australia, occupying an estimated 85 million ha of continental land mass. Historically, deforestation was carried out in many sheep-rearing regions to promote pasture growth but this has not occurred within recent decades and many wool producers have invested in planting trees as well as preserving patches of remnant vegetation. Although the limitations of single environmental impact studies are recognised, this paper focuses on the contribution of carbon sequestration in trees and shrubs on sheep farms to the global warming potential impact category in life cycle assessment of wool. The analysis represents three major wool-producing zones of Australia. Based on default regional yields as applied in Australia’s National Inventory model, FullCAM, CO2 removals in planted exotic pines and mixed native species were estimated to be 5.0 and 3.0 t CO2 ha–1 year–1, respectively, for the Northern Tablelands of New South Wales in the ‘high-rainfall zone’ and 1.4 t CO2 ha–1 year–1 for mixed native species in the ‘sheep-wheat zone’ of Western Australia. Applying modified factors allowing for the higher measured growth rates in regions with rainfall >300 mm, gave values for native species reforestation of 4.4 and 2.0 t CO2 ha–1 year–1 for New South Wales and Western Australia, respectively. Sequestration was estimated to be 0.07 t CO2 ha–1 year–1 over 100 years for chenopod shrublands of the ‘pastoral zone’ of South Australia but this low rate is significant because of the extent of regeneration. Sequestration of soil organic carbon in improved permanent pastures in the New South Wales Northern Tablelands was evaluated to be highly uncertain but potentially significant over large areas of management. Improved data and consistent methodologies are needed for quantification of these benefits in life cycle assessment studies for wool and sheep meat, and additional impact categories, such as biodiversity, need to be included if the public and private benefits provided by good management of vegetation resources on farms are to be more fully recognised.
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Dai, Taoyan, Liquan Wang, Tienan Li, Pengpeng Qiu, and Jun Wang. "Study on the Characteristics of Soil Erosion in the Black Soil Area of Northeast China under Natural Rainfall Conditions: The Case of Sunjiagou Small Watershed." Sustainability 14, no. 14 (July 6, 2022): 8284. http://dx.doi.org/10.3390/su14148284.
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In the black soil area, where soil erosion is severe and the soil is in urgent need of ecological restoration, providing reasonable and practical measures to prevent soil erosion and restore the soil is an urgent issue at present. In this study, nine runoff plots were deployed in Bin County, the core area of soil erosion control, to monitor runoff and soil loss long-term, simulated by the erosion potential method (EPM) for comparison. Studies have shown that soil erosion is strongly influenced by soil conservation measures, land use, and vegetation cover. In contrast, slope, pre-soil moisture content, and soil crusting due to rainfall can affect erosion in a single rainfall event. The most severe soil erosion was in bare land, up to 1093.58 t km−2 a−1, followed by longitudinal ridge tillage land (751.88 t km−2 a−1) and cross ridge tillage land (31.58 t km−2 a−1). The shrublands and mixed forests planted for ecological restoration experienced almost no erosion. The soil loss rate of the cross ridge tillage and ecological restoration plots was much lower than the allowable soil loss rate (200 t km−2 a−1). Under erosive storms, longitudinal ridge tillage can produce soil loss rates that far exceed those of bare ground. The change from longitudinal ridge tillage to cross ridge tillage on gentle slopes can effectively prevent soil erosion in the study area. The vegetation restoration measures of planting shrubs such as Amorpha fruticosa Linn. are incredibly effective in the ecological restoration of wastelands in black soil areas. For the black soil area after the retreat, the vertical structure of vegetation can be improved by planting shrubs at the bottom, thus achieving a good restoration effect.
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Wu, Fang, Yuan Jiang, Yan Wen, Shoudong Zhao, and Hui Xu. "Spatial synchrony in the start and end of the thermal growing season has different trends in the mid-high latitudes of the Northern Hemisphere." Environmental Research Letters 16, no. 12 (November 19, 2021): 124017. http://dx.doi.org/10.1088/1748-9326/ac3696.
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Abstract Changes in spatial synchrony in the growing season have notable effects on species distribution, cross-trophic ecological interactions and ecosystem stability. These changes, driven by non-uniform climate change were observed on the regional scale. It is still unclear how spatial synchrony of the growing season on the climate gradient of the mid-high latitudes of the Northern Hemisphere and ecoregions, has changed over the past decades. Therefore, we calculated the start, end, and length of the thermal growing season (SOS, EOS, and LOS, respectively), which are indicators of the theoretical plant growth season, based on the daily-mean temperature of the Princeton Global Forcing dataset from 1948 to 2016. Spatial variations in the SOS, EOS and LOS along spatial climate gradients were analyzed using the multivariate-linear regression model. The changes of spatial synchrony in the SOS, EOS and LOS were analyzed using the segmented model. The results showed that in all ecoregions, spatially, areas with higher temperature tended to have an earlier SOS, later EOS and longer LOS. However, not all the areas with higher precipitation tended to have a later SOS, later EOS, and shorter LOS. The spatial synchrony in the SOS decreased across the entire study area, whereas the EOS showed the opposite trend. Among the seven ecoregions, spatial synchrony in the SOS in temperate broadleaf/mixed forests and temperate conifer forests changed the most noticeably, decreasing in both regions. Conversely, spatial synchrony in the EOS in the taiga, temperate grasslands/savannas/shrublands and tundra changed the most noticeably, increasing in each region. These may have important effects on the structure and function of ecosystems, especially on the changes in cross-trophic ecological interactions. Moreover, future climate change may change the spatial synchrony in the SOS and EOS further; however, the actual impact of such ongoing change is largely unknown.
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López, Carlos López, Rocío Rosa García, Luis M. M. Ferreira, Urcesino García, Koldo Osoro, and Rafael Celaya. "Impacts of horse grazing on botanical composition and diversity in different types of heathland." Rangeland Journal 39, no. 4 (2017): 375. http://dx.doi.org/10.1071/rj17079.
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Plant dynamics under horse grazing was studied in a three-year field experiment in heather-gorse shrublands in NW Spain. The experimental design consisted of three vegetation types with four replicates (paddocks): (1) heather (Ericaceae)-dominated (H), (2) gorse (Ulex gallii Planch.)-dominated (G), and (3) co-dominated by gorse and heath-grasses (GG). Each paddock (1.2 ha) was grazed from May to October by two crossbred mature mares (310 ± 52 kg bodyweight), one dry and one lactating (plus foal). Two other paddocks (one in H and one in GG) were excluded from grazing. Plant cover and height were sampled three times a year (spring, summer, and autumn) with a point-quadrat method. Floristic composition and diversity were annually sampled at 10 25-m2 quadrats per paddock. Data were subjected to mixed models for repeated-measures and redundancy analyses. Horse grazing resulted in overall increases (P < 0.001) in heather and herbaceous cover (from 13% to 27%, and from 16% to 23%, respectively), and decreases (P < 0.001) in gorse cover and height (from 35% to 17%; from 30 to 25 cm), with scarce differences among vegetation types. Floristic diversity (species richness and Shannon index) increased more over time in grazed than in ungrazed paddocks. Redundancy analyses revealed that grazing effects on plant species assemblages depended on vegetation type, and that plant communities evolved differently between grazing treatments for both abundance and frequency data. Some herbaceous species characteristic of heathlands were favoured by horse grazing. Horse grazing reduced gorse dominance in G and GG vegetation, controlling excessive accumulation of combustible material and reducing fire risk, and promoted the presence of species of conservation interest, so it offers a promising management tool for the restoration of heathlands and their biodiversity.
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Sufardi, S., S. Syafruddin, T. Arabia, K. Khairullah, and HA Umar. "Comparison of carbon content in soil and biomass in various types of sub-optimal dryland use in Aceh Besar, Indonesia." IOP Conference Series: Earth and Environmental Science 1116, no. 1 (December 1, 2022): 012049. http://dx.doi.org/10.1088/1755-1315/1116/1/012049.
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Abstract This study was conducted to compare the content of carbon in soil and in biomass vegetation in various types of sub-optimal dryland in Aceh Besar district, Indonesia. Soil samples were collected from seven soil depths from 0 to 100 cm under 12 land uses including primary forest, secondary forest, pine forest, Eucalyptus forests, teak forest, forest shrubs, shrublands, and grasslands, mixed gardens, moorlands, rainfed rice fields, and bare lands. The measurement of plant biomass is differentiated according to the type of vegetation based on the BSN (2020) procedure [1]. The biomass of vegetations used allometric equations. The results of the study showed that the C content of the soil at a depth of 0-30 cm was higher than the C content at 30-100 cm. Carbon soil potential at the depth of 0-100 cm and biomass carbon contents in the sub-optimal dryland of Aceh Besar varies greatly between land-use types. The primary forest has the highest potential for soil carbon and biomass carbon compared to other land-use types. Soil and biomass C potentials in the primary forest were 332.28 ± 28.75 t ha-1 and 241.71 ± 24.46 t ha-1 (70.4%), respectively, with soil C stock of 25,103.68 Gg. The lowest soil C potential was found in bare land, namely 57.54±5.87 t ha-1 with a biomass C potential of 0.53 ±0.06 t ha-1, while the lowest soil C stock was found in the teak forest, which was 4.83 Gg. There is a positive correlation between soil C stock and biomass C content. The ratio of soil C and biomass C in the sub-optimal dryland of Aceh Besar varied from 0.01 to 1.57.
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Darwish, Talal, Thérèse Atallah, and Ali Fadel. "Challenges of soil carbon sequestration in the NENA region." SOIL 4, no. 3 (September 26, 2018): 225–35. http://dx.doi.org/10.5194/soil-4-225-2018.
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Abstract. The Near East North Africa (NENA) region spans over 14 % of the total surface of the Earth and hosts 10 % of its population. Soils of the NENA region are mostly highly vulnerable to degradation, and future food security will much depend on sustainable agricultural measures. Weather variability, drought and depleting vegetation are dominant causes of the decline in soil organic carbon (SOC). In this work the status of SOC was studied, using a land capability model and soil mapping. The land capability model showed that most NENA countries and territories (17 out of 20) suffer from low productive lands (> 80 %). Stocks of SOC were mapped (1:5 000 000) in topsoils (0–0.30 m) and subsoils (0.30–1 m). The maps showed that 69 % of soil resources are shown to have a stock of SOC below the threshold of 30 tons ha−1. The stocks varied between ≈10 tons ha−1 in shrublands and 60 tons ha−1 for evergreen forests. Highest stocks were found in forests, irrigated crops, mixed orchards and saline flooded vegetation. The stocks of soil inorganic carbon (SIC) were higher than those of SOC. In subsoils, the SIC ranged between 25 and 450 tons ha−1, against 20 to 45 tons ha−1 for SOC. Results highlight the contribution of the NENA region to global SOC stock in the topsoil (4.1 %). The paper also discusses agricultural practices that are favorable to carbon sequestration such as organic amendment, no till or minimum tillage, crop rotation and mulching and the constraints caused by geomorphological and climatic conditions. The effects of crop rotations on SOC are related to the amounts of above and belowground biomass produced and retained in the system. Some knowledge gaps exist, especially in aspects related to the impact of climate change and effect of irrigation on SOC, and on SIC at the level of the soil profile and soil landscape. Still, major constraints facing soil carbon sequestration are policy-relevant and socioeconomic in nature, rather than scientific.
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Moseby, K. E., and J. L. Read. "Population Dynamics and Movement Patterns of Bolam's Mouse, Pseudomys bolami, at Roxby Downs, South Australia." Australian Mammalogy 20, no. 3 (1998): 353. http://dx.doi.org/10.1071/am98353.
Full textAbstract:
Basic ecological data were collected on Bolam's mouse, Pseudomys bolami, during a six year trapping study at Roxby Downs in northern South Australia. Pseudomys bolami inhabited mixed arid land systems in the Roxby Downs area, sheltering in the longitudinal orange sand dunes but foraging at night principally on the adjacent chenopod swales. Distances of up to 334m were traversed in a single night and recapture rates were high within trapping sessions but low between sessions suggesting wide-ranging movements and short-term residency. Dietary observations imply an omnivorous diet. Whilst the closely related P. hermannsburgensis is regarded as having an opportunistic breeding strategy, P. bolami reproduced opportunistically but also regularly in spring and early summer. Different reproductive strategies may be influenced by the latitudinal distribution of P. bolami near the southern margin of the arid-zone, where rainfall can occur at any time of year but winter rainfall is more predictable. This contrasts with P. hermannsburgensis, which inhabits more northerly arid areas where rainfall is erratic and unpredictable. There was a 10 fold fluctuation in P. bolami captures over the trapping period with numbers of P. bolami and house mice, Mus domesticus peaking 12 months after above average rains during 1992. Rodent captures remained high for two years afterwards. Although P. bolami persisted throughout the study period, M. domesticus was only present when conditions were above average. Trap success of P. bolami or M. domesticus did not vary between the five sub habitats at the 1 ha study site. However, trap success of P. bolami was positively related to vegetation cover, particularly cover of low bluebush, Maireana astrotricha. Maireana astrotricha may be important in providing both food and cover for P. bolami, a scenario consistent with the utilisation of spinifex, Triodia spp. by P. hermannsburgensis in the northern arid-zone. Past over- grazing of chenopod shrublands may have reduced cover and contributed to the suggested decline in the distribution of P. bolami.
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Sesnie, Steven, Holly Eagleston, Lacrecia Johnson, and Emily Yurcich. "In-Situ and Remote Sensing Platforms for Mapping Fine-Fuels and Fuel-Types in Sonoran Semi-Desert Grasslands." Remote Sensing 10, no. 9 (August 27, 2018): 1358. http://dx.doi.org/10.3390/rs10091358.
Full textAbstract:
Fire has historically played an important role in shaping the structure and composition of Sonoran semi-desert grassland vegetation. Yet, human use and land management activities have significantly altered arid grassland ecosystems over the last century, often producing novel fuel conditions. The variety of continuously updated satellite remote sensing systems provide opportunities for efficiently mapping combustible fine-fuels and fuel-types (e.g., grass, shrub, or tree cover) over large landscapes that are helpful for evaluating fire hazard and risk. For this study, we compared field ceptometer leaf area index (LAI) measurements to conventional means for estimating fine-fuel biomass on 20, 50 m × 20 m plots and 431, 0.5 m × 0.5 m quadrats on the Buenos Aires National Wildlife Refuge (BANWR) in southern Arizona. LAI explained 65% of the variance in fine-fuel biomass using simple linear regression. An additional 19% of variance was explained from Random Forest regression tree models that included herbaceous plant height and cover as predictors. Field biomass and vegetation measurements were used to map fine-fuel and vegetation cover (fuel-type) from plots on BANWR comparing outcomes from multi-date (peak green and dormant period) Worldview-3 (WV3) and Landsat Operational Land Imager (OLI) imagery. Fine-fuel biomass predicted from WV3 imagery combined with terrain information from a digital elevation model explained greater variance using regression tree models (65%) as compared to OLI models (58%). Vegetation indices developed using red-edge bands as well as modeled bare ground and herbaceous cover were important to improve WV3 biomass estimates. Land cover classification for 11 cover categories with high spatial resolution WV3 imagery showed 80% overall accuracy and highlighted areas dominated by non-native grasses with 87% user’s class accuracy. Mixed native and non-native grass and shrublands showed 59% accuracy and less common areas dominated by native grasses on plots showed low class accuracy (23%). Digital data layers from WV3 models showed a significantly positive relationship (r2 = 0.68, F = 119.2, p < 0.001) between non-native grass cover (e.g., Eragrostis lehmanniana) and average fine-fuel biomass within refuge fire management units. Overall, both WV3 and OLI produced similar fine-fuel biomass estimates although WV3 showed better model performance and helped characterized fine-scale changes in fuel-type and continuity across the study area.
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Juncu, Daniel, Xavier Ceamanos, Isabel F. Trigo, Sandra Gomes, and Sandra C. Freitas. "Upgrade of LSA-SAF Meteosat Second Generation daily surface albedo (MDAL) retrieval algorithm incorporating aerosol correction and other improvements." Geoscientific Instrumentation, Methods and Data Systems 11, no. 2 (November 24, 2022): 389–412. http://dx.doi.org/10.5194/gi-11-389-2022.
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Abstract. MDAL is the operational Meteosat Second Generation (MSG)-derived daily surface albedo product that has been generated and disseminated in near real time by EUMETSAT Satellite Application Facility for Land Surface Analysis (LSA-SAF) since 2005. We propose and evaluate an update to the MDAL retrieval algorithm which introduces the accounting for aerosol effects as well as other scientific developments: pre-processing recalibration of radiances acquired by the SEVIRI instrument aboard MSG and improved coefficients for atmospheric correction as well as for albedo conversion from narrow- to broadband. We compare the performance of MDAL broadband albedos pre- and post-upgrade with respect to three types of reference data: the EPS Ten-Day Albedo product ETAL is used as the primary reference, while albedo derived from in situ flux measurements acquired by ground stations and MODIS MCD43D albedo data are used to complete the validation. For the comparison to ETAL – conducted over the whole coverage area of SEVIRI – we see a reduction in average white-sky albedo mean bias error (MBE) from −0.02 to negligible levels (<0.001) and a reduction in average mean absolute error (MAE) from 0.034 to 0.026 (−24 %). Improvements can be seen for black-sky albedo as well, albeit less pronounced (14 % reduction in MAE). Further analysis distinguishing individual seasons, regions and land covers show that performance changes have spatial and temporal dependence: for white-sky albedo we see improvements over almost all regions and seasons relative to ETAL, except for Eurasia in winter; resolved by land cover we see a similar effect with improvements for all types for all seasons except winter, where some types exhibit slightly worse results (crop-, grass- and shrublands). For black-sky albedo we similarly see improvements for all seasons when averaged over the full data set, although sub-regions exhibit clear seasonal dependence: the performance of the upgraded MDAL version is generally diminished in local winter but better in local summer. The comparison with in situ observations is less conclusive due to the well-known problem of the spatial representativeness of near-ground observations with respect to satellite pixel footprint sizes. Comparison with MODIS at the same locations shows mixed results in terms of change in performance following the proposed upgrade but proves the good quality of the MDAL products in general. Based on the evidence presented in this study, we consider the updated algorithm version to be able to deliver a valuable improvement of the operational MDAL product. This improvement is two-fold: primarily, there is the refinement of the albedo values themselves; secondarily, the increased alignment with the ETAL product is beneficial for those who wish to exploit synergies between EUMETSAT's geostationary and polar satellites to generate data sets based on the LSA-SAF albedo products from the two different missions.
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Bélanger, Luc, Austin Reed, and Jean-Luc DesGranges. "Reproductive variables of American black ducks along the St. Lawrence estuary, 1963-1991." Canadian Journal of Zoology 76, no. 6 (June 1, 1998): 1165–73. http://dx.doi.org/10.1139/z98-006.
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We examine data from different surveys conducted from 1963 to 1991 in the Baie de lIsle Verte National WildlifeArea and the surrounding offshore islands, an approximately 20-km2 coastal segment of the St.Lawrence estuary in Quebec.We summarize data regarding various aspects of the nesting ecology of the American black duck (Anas rubripes) (n = 812nests). Mean laying date, average clutch size, and apparent nesting success did not differ among years (P > 0.05). Black ducksnested earlier on islands (mean Julian date 120.0 vs. 121.3;P = 0.03), but mean clutch size and nesting success on islands didnot differ from those on the mainland (P> 0.05). Among mainland-nesting black ducks, those nesting in mixed stands of treesand bushes initiated nests almost 10 days earlier than those nesting in the two other types of nest cover (mean Julian date 124.0vs. 134.4 and 139.6). Black ducks nesting in such habitats as woodlots, peat bogs, or shrubland laid a larger number of eggsthan those nesting in the two other habitat types (mean 9.7 vs. 8.8 and 9.4). Finally, we observed that nesting success of ducksnesting in woodlots, peat bogs, and shrubland and in mixed stands of trees and bushes or of herbaceous plants and shrubs wasup to three times higher than at other sites (P<= 0.05). We conclude that in addition to protection and restoration of existingislands, more emphasis should be placed on conserving peat bogs, coniferous woodlots, and shrubland, because they alsoconstitute good mainland-nesting habitat for black ducks along the St. Lawrence estuary.
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Pirintsos, Stergios Arg, Stefano Loppi, Anastasia Dalaka, and Vincenzo De Dominicis. "EFFECTS OF GRAZING ON EPIPHYTIC LICHEN VEGETATION IN A MEDITERRANEAN MIXED EVERGREEN SCLEROPHYLLOUS AND DECIDUOUS SHRUBLAND (NORTHERN GREECE)." Israel Journal of Plant Sciences 46, no. 4 (May 13, 1998): 303–7. http://dx.doi.org/10.1080/07929978.1998.10676740.
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The epiphytic lichen vegetation of a heavily grazed Mediterranean mixed evergreen sclerophyllous and deciduous shrubland was studied. Differences in the epiphytic lichen vegetation seem to be largely determined by changes in the architecture of the bushes as well as by the differences in the space between them. In some cases, despite grazing pressure, the epiphytic lichen vegetation does not change dramatically.
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Marino, Eva, Carmen Hernando, Javier Madrigal, Carmen Díez, and Mercedes Guijarro. "Fuel management effectiveness in a mixed heathland: a comparison of the effect of different treatment types on fire initiation risk." International Journal of Wildland Fire 21, no. 8 (2012): 969. http://dx.doi.org/10.1071/wf11111.
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Fuel management is commonly used to reduce fire risk in fire-prone shrubland, but information about the real efficacy of the different techniques is scarce. In this study, we assessed in the laboratory the effects of different treatment types on fire initiation risk in a mixed heathland. The effects of two mechanical treatments and of prescribed burning were compared with untreated vegetation. Flammability tests were performed in samples of the regenerated shrubs and fine ground fuels present 2 years after treatments. Results indicate that all treatments were effective in reducing fire initiation risk in regenerated shrubs, but not in fine ground fuels. Recovery of vegetation differed between treatments, and treatment type had a significant effect on flammability, mainly affecting fire sustainability. Wind speed had a minor effect on shrub fuel flammability, whereas fuel moisture had a significant effect. The flammability of fine ground fuels differed significantly depending on fuel moisture content, even at the low levels tested. Logistic models were fitted to predict successful fire sustainability, and the probability of initial propagation was obtained as a function of treatment type, fuel moisture content and fuel structural characteristics. This study provides new insights into wildfire prevention in shrubland, and compares the effectiveness of different fuel treatment techniques.
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Marino, Eva, Carmen Hernando, Javier Madrigal, and Mercedes Guijarro. "Short-term effect of fuel treatments on fire behaviour in a mixed heathland: a comparative assessment in an outdoor wind tunnel." International Journal of Wildland Fire 23, no. 8 (2014): 1097. http://dx.doi.org/10.1071/wf13175.
Full textAbstract:
Fuel management is one of the main challenges for wildfire prevention in the Mediterranean region, where wildfires have important environmental and socioeconomic effects. Different treatments are usually applied in fire-prone shrubland to try to modify its flammability. However, a knowledge gap on the effectiveness of fuel management techniques still exists. We studied the effects of two mechanical treatments (shrub crushing and shrub clearing with removal) and of prescribed burning, on fire behaviour, and compared them with untreated vegetation. Experimental burns in 0.8 × 6 m samples of regenerated shrubs 2 years after treatments were performed in an outdoor wind tunnel. All fuel treatments effectively modified fire behaviour, but no significant difference between treatment types was observed. Shrub fuel structure was the main factor affecting fire behaviour. Reduction of fuel load and height, especially necromass fraction, decreased flame height and fire intensity but did not affect fire rate of spread. Moisture contents of live and dead fuel fractions were not significant as independent parameters, but the average moisture level of the shrub fuel complex showed a relevant effect in determining fire behaviour. Temperature regime within and above the shrubs was also related to shrub fuel structure. This study contributes to understanding fuel management in shrubland by providing information about different fuel treatments effects on fire behaviour.
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Marchant, R., A. Cleef, S. P. Harrison, H. Hooghiemstra, V. Markgraf, J. van Boxel, T. Ager, et al. "Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years ago." Climate of the Past 5, no. 4 (December 1, 2009): 725–67. http://dx.doi.org/10.5194/cp-5-725-2009.
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Abstract. The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small; change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America show a change in biome assignment, but to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucatán peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation reflecting a generally cool and dry environment. Cool grass/shrubland is prevalent in southeast Brazil whereas Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain forest indicating that forest was present at some locations at the LGM. Some sites in Central Mexico and lowland Colombia remain unchanged in the biome assignments of warm mixed forest and tropical dry forest respectively, although the affinities that these sites have to different biomes do change between 18 000±1000 14C yr BP and present. The "unresponsive" nature of these sites results from their location and the impact of local edaphic influence.
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Guan, Huiling, and Jiangwen Fan. "Effects of vegetation restoration on soil quality in fragile karst ecosystems of southwest China." PeerJ 8 (July 2, 2020): e9456. http://dx.doi.org/10.7717/peerj.9456.
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Soil quality assessment is important for karst ecosystems where soil erosion is significant. A large amount of vegetation restoration has been implemented since the early 21st century in degraded karst areas across southwestern China. However, the impacts on soil quality of different restoration types rarely have been compared systematically. In the current study, we investigated the soil quality after a number of vegetation restoration projects as well as their adjacent cropland by analyzing soil samples. Six vegetation restoration types were evaluated, including one natural restoration (natural shrubland, protected for 13 years), three economic forests (4 years Eucalyptus robusta, 4 years Prunus salicina and 6 years Zenia insignis) and two mixed forests (1 year Juglans regia–crop and 13 years Toona sinensis-Pennisetum purpureum ). We evaluated the benefits of different restoration types more accurately by setting each adjacent cropland as the control and setting the variation between the corresponding restored and control site as the evaluation object so that the background differences of six sites could be eliminated. The results indicated that natural shrubland, Toona sinensis-Pennisetum purpureum and Zenia insignis were effective in improving soil quality index (SQI) in degraded karst cropland largely due to their higher SOC and TN content. The variation of SQI (VSQI) of natural shrubland was significantly higher than that in Eucalyptus robusta, Prunus salicina and Juglans regia-crop in total soil layer (0–30 cm) (P < 0.05), indicating natural shrubland had better capacity to improve soil quality. The boosting regression tree model revealed that vegetation restoration type explained 73.49% and restoration time explained 10.30% of the variation in VSQI, which confirmed that vegetation restoration type and restoration time are critical for achieving soil reserves. Therefore, it is vital to select appropriate vegetation type in restoration projects and recovery for a long time in order to achieve better soil quality. The current study provides a theoretical basis on which to assess the effects of different vegetation restoration types on the heterogeneous degraded karst areas.
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Dega, Mulugeta B., Alemayehu N. Emana, and Habtamu A. Feda. "The Impact of Catchment Land Use Land Cover Changes on Lake Dandi, Ethiopia." Journal of Environmental and Public Health 2022 (June 17, 2022): 1–8. http://dx.doi.org/10.1155/2022/4936289.
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Highland freshwater lakes are currently threatened with catchment land use land cover changes particularly in developing countries like Ethiopia despite their wide range of valuable ecosystem services. This study was conducted to assess trends of catchment land use land cover change and associated impacts on a highland Lake, Dandi over three decades from 1990 to 2020 years period based on GIS (ArcMap 10.4.1) and remote sensing (ERDAS Imagine 14) software as well as questioner survey, key informant interviews, and field observation. The study covered 3,794 ha with five major land use land covers, namely mixed agriculture/settlement, bush-/shrubland, grassland, bare land, and water body (Lake Dandi). The assessment revealed that farmland/residential area increased by 593 ha (35.34%), while bare land, grassland, shrubland, and Lake Dandi decreased by 290 ha (26.12%), 218 ha (12.15%), 57 ha (6.85%), and 28 ha (19.53%), respectively. Responses also indicated increased farmland/settlement area (66.66%) and declined areas of bare land (84.63%), bush-/shrubland (84.86%), grassland (96.96%), and Lake Dandi (61.05%). Furthermore, responses indicated expanding agricultural land use (48%), population growth (38%), climate change (32%), overgrazing (30%), and poverty (28%) as major factors currently threatening the lake and its ecosystem services. Field observation also revealed expansion of agricultural land use in the catchment of Lake Dandi including in steeper slopes and hillsides that might exacerbate on-site soil erosion as well as lake sedimentation and toxic contamination. Thus, results indicated deterioration in the storage capacity and water quality of Lake Dandi due to catchment land use land cover change that might in turn adversely affect its ecosystem services and the resident biota suggesting urgent intervention.
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Li, Qingkang, and Keping Ma. "Factors affecting establishment of Quercus liaotungensis Koidz. under mature mixed oak forest overstory and in shrubland." Forest Ecology and Management 176, no. 1-3 (March 2003): 133–46. http://dx.doi.org/10.1016/s0378-1127(02)00274-8.
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Hu, Jian, Yihe Lü, Bojie Fu, Alexis J. Comber, and Paul Harris. "Quantifying the effect of ecological restoration on runoff and sediment yields." Progress in Physical Geography: Earth and Environment 41, no. 6 (November 5, 2017): 753–74. http://dx.doi.org/10.1177/0309133317738710.
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Ecological restoration can result in extensive land use transitions which may directly impact on water runoff and sediment loss and thus influence tradeoffs between multiple hydrological and soil ecosystem services. However, quantifying the effect of these transitions on runoff and sediment yields has been a challenge over large spatial scales. This study integrated and synthesized 43 articles and 331 runoff experimental plots in the Loess Plateau of China under natural rainfall to quantify the impacts of land use transitions on (a) runoff and sediment production, (b) runoff and soil loss reduction effectiveness, and (c) the tradeoffs between runoff and soil erosion. The effects of ecological restoration on runoff and sediment yields were quantified using a general mixed linear meta-regression model with a restricted maximum likelihood estimator on overall and individual ecological restoration types. The results showed that artificial grassland, forest, natural grassland, and shrubland had higher runoff and sediment reduction effectiveness. The annual runoff reduction effectiveness of the ecological restoration overall was 72.18% with the effects of artificial grassland, natural grassland, shrubland, and forest at 71.89%, 50.60%, 73.18%, and 73.08%, respectively. The annual sediment reduction effectiveness of the overall ecological restoration was 99.9% without a significant difference among the four land uses associated with ecological recovery. In addition, shrubland and forest significantly reduced sediment yields with relatively high runoff costs. Natural grassland was optimal for balancing water provisioning and soil conservation, and artificial grassland was second to natural grassland in this respect. Meanwhile, newly unmanaged abandoned land and cropland had relative weak functionality with regard to soil and water conservation. The implications of this study’s findings are discussed along with their potential to contribute to an improved understanding of the effects of ecological restoration on water supply and soil retention for the water-limited terrestrial ecosystem at a regional scale.
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Marchant, R., S. P. Harrison, H. Hooghiemstra, V. Markgraf, J. H. van Boxel, T. Ager, L. Almeida, et al. "Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years." Climate of the Past Discussions 5, no. 1 (February 10, 2009): 369–461. http://dx.doi.org/10.5194/cpd-5-369-2009.
Full textAbstract:
Abstract. The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small. Patterns of change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America also show a change in biome assignment to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucatán peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation that reflects a generally cool and dry environment. Cool grass/shrubland prevalent in southeast Brazil, Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain forest indicating that forest was present at some locations at the LGM. Some sites in Central México and lowland Colombia remain unchanged in their biome assignments, although the affinities that these sites have to different biomes do change between 18 000±1000 14C yr BP and present. The "unresponsive" nature of these sites results from their location and the impact of local edaphic influence.
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Asrul, Asrul, Yumna Yumna, and Srida Mitra Ayu. "LAJU INFILTRASI PADA PENGGUNAAN LAHAN DI IUPHKM DI HUTAN LINDUNG TANDUNG BILLA KELURAHAN BATTANG KECAMATAN WARA BARAT KOTA PALOPO." Jurnal Penelitian Kehutanan BONITA 3, no. 1 (July 26, 2021): 35. http://dx.doi.org/10.55285/bonita.v3i1.595.
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The low infiltration rate causes most of the rainwater that falls to the ground to become surface runoff, and only a small portion of the water can enter the ground as groundwater storage. The infiltration in the Tandung Billa IUPHKm location includes the use of forest land, shrubs, and mixed gardens, and the management carried out by the community at the Tandung Billa IUPHkm location is the cultivation of agricultural/plantation crops under tree stands in hilly or slightly sloping areas. Land use in the Tandung Billa Community Forest Utilization Business Permit (IUPHKm) consists of forest land, shrubs, and mixed gardens; each land use affects soil and land conditions, which in turn will affect the infiltration rate of the land. Therefore it is necessary to know how the infiltration rate in forest land use, mixed garden shrubs. Measurement of the infiltration rate was carried out by taking soil samples for physical properties, and soil moisture content in three different land uses, namely forest, shrub, and mixed garden land use; the measurement was carried out using a double-ring infiltrometer. The results showed that the infiltration rate on forest land was classified as medium-fast, namely = 83 mm / hour, with clay texture, then the infiltration rate in shrubland was classified as moderate, namely = .62 mm / hour, with clay soil texture and clay. The infiltration rate in mixed garden land/agroforestry is classified as moderate, namely = 53 mm / hour with a dusty clay texture.
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Whitlock, Cathy, Maria Martha Bianchi, Patrick J. Bartlein, Vera Markgraf, Jennifer Marlon, Megan Walsh, and Neil McCoy. "Postglacial vegetation, climate, and fire history along the east side of the Andes (lat 41–42.5°S), Argentina." Quaternary Research 66, no. 2 (September 2006): 187–201. http://dx.doi.org/10.1016/j.yqres.2006.04.004.
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AbstractThe history of the low-elevation forest and forest-steppe ecotone on the east side of the Andes is revealed in pollen and charcoal records obtained from mid-latitude lakes. Prior to 15,000 cal yr BP, the vegetation was characterized by steppe vegetation with isolated stands of Nothofagus. The climate was generally dry, and the sparse vegetation apparently lacked sufficient fuels to burn extensively. After 15,000 cal yr BP, a mixture of Nothofagus forest and shrubland/steppe developed. Fire activity increased between 13,250 and 11,400 cal yr BP, contemporaneous with a regionally defined cold dry period (Huelmo/Mascardi Cold Reversal). The early-Holocene period was characterized by an open Nothofagus forest/shrubland mosaic, and fire frequency was high in dry sites and low in wet sites; the data suggest a sharp decrease in moisture eastward from the Andes. A shift to a surface-fire regime occurred at 7500 cal yr BP at the wet site and at 4400 cal yr BP at the dry site, preceding the expansion of Austrocedrus by 1000–1500 yr. The spread of Austrocedrus is explained by a shift towards a cooler and wetter climate in the middle and late Holocene. The change to a surface-fire regime is consistent with increased interannual climate variability and the onset or strengthening of ENSO. The present-day mixed forest dominated by Nothofagus and Austrocedrus was established in the last few millennia.
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Majer, Jonathan D. "Ant recolonisation of rehabilitated bauxite mines of Poços de Caldas, Brazil." Journal of Tropical Ecology 8, no. 01 (February 1992): 97–108. http://dx.doi.org/10.1017/s0266467400006155.
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ABSTRACTThe ant species were sampled in one campo (grassy shrubland), one mata (semideciduous rain forest) and 11 rehabilitated bauxite mine plots at Poços de Caldas, in the humid sub-tropical climatic region of Brazil. Rehabilitation was either by planting AustralianEucalyptusspp, the BrazilianMimosa scabrellatree, or by planting mixed mata trees. Sixty-eight ant species were recorded, of which 26 were exclusively found in the native vegetation and 16 were confined to the rehabilitated plots. Ant species richness built up most rapidly in areas rehabilitated with mixed mata species and least rapidly in areas withEucalyptus. Younger rehabilitated plots appeared to be developing a campo-type ant community, although evidence indicates that more mata ant species will colonise once tree canopy closure takes place. Rate of ant return in Australia is positively correlated with the quantity and distribution of rainfall – the rates in the current study concur with those from humid sub-tropical climatic zones within Australia, suggesting that similar constraints to the succession may be operating. If found to be the case, this would have practical implications for planning and evaluating the success of rehabilitation.
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Henkin, Zalmen. "Cattle grazing and vegetation management for multiple use of Mediterranean shrubland in Israel." Israel Journal of Ecology and Evolution 57, no. 1-2 (May 6, 2011): 43–51. http://dx.doi.org/10.1560/ijee.57.1-2.43.
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Regenerating sclerophyllous shrubby and woody vegetation on uncultivated land in the Mediterranean region is a source of browse for goats, cattle, camels, and wildlife. Traditionally, this Mediterranean shrubland was intensively grazed by mixed herds, predominantly goats that maintained an open landscape. In addition, the vegetation supplied timber for fuel and construction, as well as culinary and medicinal plants. Patches of deeper soil were cultivated, often on terraces. In recent years, goat husbandry has declined and the establishment of protected areas has favored the regeneration of a dense woodland dominated byQuercus calliprinos. Commercial beef husbandry has largely replaced the traditional management system. After initial thinning to open up the thickets, the oak woodland can sustain a viable beef herd with moderate supplementation. Appropriate management of grazing, control of the shrub component and, in some cases, soil nutrient amelioration, can lead to the development of relatively stable, open woodland with nutritious and usually attractive herbaceous patches. In addition to animal production, these rangelands have significant recreational, conservation, and landscape values that are becoming increasingly important as urbanization increases. Such landscapes provide a wide range of ecological services and are less of a fire hazard than the undisturbed regenerating successional shrub thickets. The multiple benefits of the open landscape can justify the expense of necessary interventions that cannot be borne by any single benefit.
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Lee, Hansol, Bong Soon Lim, Dong Uk Kim, A. Reum Kim, Jae Won Seol, Chi Hong Lim, Ji Hyun Kil, Jeong Sook Moon, and Chang Seok Lee. "Decline and Passive Restoration of Forest Vegetation Around the Yeocheon Industrial Complex of Southern Korea." Forests 11, no. 6 (June 12, 2020): 674. http://dx.doi.org/10.3390/f11060674.
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This study was carried out to clarify the vegetation decline due to air pollutants emitted in the process of industrial activities and the passive restoration of the vegetation due to socioeconomic changes after economic growth. To achieve this goal, we investigated the spatial distribution of vegetation, differences in species composition and diversity among vegetation types different in damage degree, vegetation dynamics, the age structure and annual ring growth of two dominant plant species, and the landscape change that occurred in this area over the last 50 years. Plant communities tended to be spatially distributed in the order of grassland, shrubland (dominated by Styrax japonicus Siebold and Zucc. community), and forests (dominated by Pinus thunbergii Parl. and Pinus densiflora Siebold and Zucc. communities), with increasing distance from the pollution source. The result of stand ordination based on vegetation data reflected the trend of such a spatial distribution. Species richness evaluated based on the species rank dominance curve was the highest in shrubland and the lowest in grassland; species richness in forests was intermediate. The size class distribution of woody plant species in four plant communities composing three vegetation types showed the possibility of them being replaced by forest in the late successional stage. However, the density of successor trees was relatively low, whereas the density of shrubby plants, which are resilient to air pollution, was very high. The age class distribution of a dominant species forming shrubland and pine forest showed that most of them were recruited after industrialization in this area. The period when young individuals in both vegetation types were recruited corresponded to the period when the annual ring growth of the pine trees that survived air pollution was reduced. An analysis of the landscape change in this area indicated that coniferous forest and agricultural field decreased greatly, whereas industrial area, residential area, mixed forest, and broadleaved forest showed increasing trends since construction of the industrial complex. As a result, the decrease in coniferous forest is usually due to vegetation decline and partially to succession, as the pine trees dominating the forest are not only sensitive to air pollution but are also shade-intolerant. The increase in mixed and broadleaved forests reflects vegetation decline or succession. Vegetation decline progressed for about 30 years after the construction of the industrial complex; it has begun to be restored passively since then, although the change has been slow. These results are in line with the environmental Kuznets curve hypothesis that environmental degradation increases in the early stages of economic growth to a certain point, and, after a turning point, economic development leads to environmental improvements—thus, there is an inverted U-shaped relationship between economic growth and environmental degradation.
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Iglesias, Virginia, Flavia Quintana, William Nanavati, and Cathy Whitlock. "Interpreting modern and fossil pollen data along a steep environmental gradient in northern Patagonia." Holocene 27, no. 7 (November 25, 2016): 1008–18. http://dx.doi.org/10.1177/0959683616678467.
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Vegetation reconstructions rest on modern vegetation–pollen rain relationships and deductive reasoning. Establishing this relationship is a nontrivial task because differences among pollen assemblages are not necessarily proportional to differences in vegetation. This task is particularly challenging in Patagonia, where some tree taxa have indistinguishable pollen, and pollen grains can be transported long distances. In this study, we describe the modern pollen of 48 lake and wetland samples from northern Patagonia (40.5–44°S) to better discriminate the major vegetation zones of the region through pollen analysis. Specifically, we focus on the performance of three methodological approaches, namely, pollen indicators, classification trees, and optimal thresholds of dissimilarity. As a proof of concept, we use the modern pollen–vegetation relationships to reconstruct the vegetation history at Laguna el Trébol (41.07°S; 71.5°W). Our results revealed that (1) pollen sums exceeding 260 grains ensured replicable vegetation reconstructions, (2) modern vegetation zones could not be separated solely by visual inspection of their pollen spectra, (3) the classification tree and optimal thresholds of dissimilarity permitted discrimination of most vegetation zones, (4) detection of nonanalog communities required use of pollen indicators or optimal thresholds of dissimilarity, and (5) vegetation at L. el Trébol was likely dominated by late glacial shrubland with no modern analogs in the study area (15,000–12,180 cal. yr BP), modern shrubland (12,180–6500 cal. yr BP) and mixed forest (6500 cal. yr BP–present). This study allows a more realistic understanding of the pollen–vegetation relationship and provides new tools for interpreting past vegetation in northern Patagonia.
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Ndubi, Antony Oduya. "Using Land Cover Change to Predict Forest Degradation Pressure Points, Eastern Mau Forest, Kenya." International Letters of Natural Sciences 71 (September 2018): 17–33. http://dx.doi.org/10.18052/www.scipress.com/ilns.71.17.
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Land cover change in any ecosystem vary in space and time. The study analyzed spatial-temporal land cover change to predict forest degradation pressure points in Eastern Mau Forest Reserve. The study objectives were to determine types and amount of spatial-temporal land cover change; land cover change drivers and; forest resources use sustainability. The study used mixed sample survey design involving purposive sampling of spatial data and cluster sampling of forest resource use data. Primary data included ground control points, field validation data and forest resource use data. Secondary data included Landsat imagery, forest and administration boundaries and settlements data. Analysis was done for 1986-2014 period using Remote Sensing and Geographical Information System. The analysis techniques used included object based image segmentation and classification, accuracy assessment and land cover change detection. Land cover types in Eastern Mau Forest consisted of indigenous forest, shrubland, grassland, plantation forest, cultivated fields, bare ground and built-up area. The analysis results depicted that cultivated fields coverage increased from 1% to 47%. Indigenous and plantation forests decreased from 43% to 36% and 34% to 7% respectively. Grassland and shrubland decreased from 16% to 8% and 6% to 2% respectively. Bare ground and built up area had a change of less than 1% each. Causes of pressure that lead to forest degradation included crop cultivation, settlement construction, livestock grazing, charcoal burning, firewood collection, logging, bee keeping and medicinal herbs extraction. Land cover change was more on the eastern side than on the western side. Indigenous and plantation forests were likely to disappear if cropland and built up area expansions were to remain unchecked. The study recommendations were: resettlement activities be eliminated in the Eastern Mau Forest; excision of forest land for crop cultivation should be discouraged; and scientific research should be carried out on sustainable plantation forest activities.
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Ndubi, Antony Oduya. "Using Land Cover Change to Predict Forest Degradation Pressure Points, Eastern Mau Forest, Kenya." International Letters of Natural Sciences 71 (September 25, 2018): 17–33. http://dx.doi.org/10.56431/p-y474vn.
Full textAbstract:
Land cover change in any ecosystem vary in space and time. The study analyzed spatial-temporal land cover change to predict forest degradation pressure points in Eastern Mau Forest Reserve. The study objectives were to determine types and amount of spatial-temporal land cover change; land cover change drivers and; forest resources use sustainability. The study used mixed sample survey design involving purposive sampling of spatial data and cluster sampling of forest resource use data. Primary data included ground control points, field validation data and forest resource use data. Secondary data included Landsat imagery, forest and administration boundaries and settlements data. Analysis was done for 1986-2014 period using Remote Sensing and Geographical Information System. The analysis techniques used included object based image segmentation and classification, accuracy assessment and land cover change detection. Land cover types in Eastern Mau Forest consisted of indigenous forest, shrubland, grassland, plantation forest, cultivated fields, bare ground and built-up area. The analysis results depicted that cultivated fields coverage increased from 1% to 47%. Indigenous and plantation forests decreased from 43% to 36% and 34% to 7% respectively. Grassland and shrubland decreased from 16% to 8% and 6% to 2% respectively. Bare ground and built up area had a change of less than 1% each. Causes of pressure that lead to forest degradation included crop cultivation, settlement construction, livestock grazing, charcoal burning, firewood collection, logging, bee keeping and medicinal herbs extraction. Land cover change was more on the eastern side than on the western side. Indigenous and plantation forests were likely to disappear if cropland and built up area expansions were to remain unchecked. The study recommendations were: resettlement activities be eliminated in the Eastern Mau Forest; excision of forest land for crop cultivation should be discouraged; and scientific research should be carried out on sustainable plantation forest activities.