Dissertations / Theses: 'Southern Pine Beetle'

1

Knebel, Larissa. "RESIN FLOW INDUCTION IN SOUTHERN PINES: IMPLICATIONS FOR DEFENSE AGAINST SOUTHERN PINE BEETLE." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-05162005-201137/.

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The interactions between conifers, bark beetles and their common fungal associates have been widely studied, in part due to the severe economic and natural losses that occur annually. Host resistance, involving constitutive and induced defensive measures, and the factors associated with pest success are now widely understood and some losses can be avoided with proper management. Recent research with Norway spruce (Picea abies) has provided additional insight into the chemical pathways involved in host resistance, and has determined that trees exposed to mechanical wounding or fungal inoculation show acquired resistance to future pathogen attacks. This aspect of defense in loblolly pine (Pinus taeda) has not been adequately investigated. However, our recent studies indicate that fungal inoculation results in elevated resin flow levels that last up to one year after treatment. Further research in southern Appalachian pines showed that elevated resin flow occurs in response to low intensity fire, and that this response is still present at 18 months after burning. These studies indicate that acquired resistance through induced resin flow in southern pines is a possibility. Further research with beetle or fungal challenges could determine new possibilities for management of both natural and planted stands in order to maximize host defenses against southern pine beetle.

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2

Petty, Saul David. "The use of mobile mapping technology to automate surveying and monitoring of southern pine beetle." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2342.

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The USDA Forest Service, Forest Health Protection, is responsible for maintaining an ORACLE database named the Southern Pine Beetle Information System (SPBIS). SPBIS was designed to store survey data for Southern Pine Beetle (SPB) infestations on federal land across the southern United States. The main purpose of this project is to improve the SPBIS database to aid in management of SPB infestations to reduce losses, to harvest compromised timber while it still has value, and to assist resource managers in preventing further infestations from becoming established. The SPBIS mobile mapping system addresses current problems with the database and offers viable solutions to each. Mobile mapping technology is a versatile tool, which is used to collect field data, with unique geospatial time tags and attributes, for integrating into or updating a GIS (Rasher 2001). The ability to efficiently collect data is essential to developing a useable database. The time required to manually enter data into the database is substantial. Ranger district personnel often do not have the time or the desire to enter data. Currently, the database is lacking years of survey and infestation data due to these negligent data entry practices, limiting the usefulness database. Currently, SPBIS data is recorded on a paper survey form. This system introduces a digital version of this form. A time study conducted to define the efficiency of each survey showed that the digital form to be more efficient with a Mann-Whitney p- value of 0.004. A comparative study was conducted to define the difference between currently estimated SPB infestation acreage and those measured using GPS. A Mann-Whitney pvalue of 0.000 shows the significant difference between the two acreage values. GPS measured acreage proved to be more accurate thus promoting the use of GPS for measuring acreage. Navigation us ing GPS coordinates was successful and will greatly decrease the time required to locate a SPB infestation on the ground. This thesis describes a mobile mapping system designed specifically to remedy the problems associated with SPBIS. This system eliminates the need for manual entry of field-collected data, while improving field data collection in terms of efficiency and accuracy.

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3

Heuss, Molly. "Evaluating The Impacts Of Southern Pine Beetle On Pitch Pine Forest Dynamics In A Newly Invaded Region." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/828.

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Southern pine beetle (SPB; Dendroctonus frontalis Zimmerman), a native insect that has historically affected pine ecosystems in the southeastern U.S., has recently expanded northward causing extensive tree mortality in pitch pine (Pinus rigida) and pitch pine-oak (Quercus spp.) forests across much of eastern Long Island, NY. Given the historic lack of SPB within these fire-dependent ecosystems, little is known regarding its impacts to forest composition, forest structure, or fuel loading. This study examined the short-term effects of SPB-induced tree mortality on the structure, composition, and fuel loading of pitch pine and pitch pine-oak communities to inform management recommendations and projections of future forest conditions and fire hazard. Overstory pine basal area declined following SPB infestation and infestation suppression management, particularly in pitch pine forests. These treatments did not impact the density or composition of seedlings and saplings, with hardwood species, including scarlet oak (Quercus coccinea), scrub oak (Quercus ilicifolia), and black gum (Nyssa sylvatica), making up the majority of species in this layer and pine representing <6% of stems. Likelihood of herbivory was influenced partly by species, with pitch pine less likely to be browsed than white oak and scarlet oak. SPB infestation significantly increased the snag component of both forest types, which largely became downed coarse woody debris (CWD) following suppression management. Treatments did not significantly influence understory species assemblages. Understory communities in pitch pine stands were characterized by Vaccinium angustifolium prior to SPB or suppression management, with these disturbances leading to an increase in the diversity of understory communities. In contrast, infestation decreased variation in understory species assemblages in pine-oak forests and encouraged regeneration of pitch pine and scarlet oak, while suppression increased diversity largely through increases in disturbance-adapted species, such as Smilax rotundifolia. SPB infestation decreased the biomass of live fuels and subsequently increased loading of dead fuels in both forest cover types. Suppression management felled preexisting and SPB-generated snags, especially in pitch pine forests, transforming vertical fuels into horizontal CWD. Collectively, results indicate SPB could functionally eliminate pitch pine without additional management intervention to maintain this species. Suppression efforts to reduce SPB impacts may accelerate succession towards hardwood dominance, particularly in pine-oak stand, leading to dramatic shifts in forest conditions across the Long Island Pine Barrens. SPB and suppression management significantly increase dead fuel loading and felling of snags during suppression served to decrease the density of ladder fuels effectively decreasing the risk of crowning. However, heavy CWD loading may also promote volatile fire behavior. Therefore, forest managers must weigh the expected potential impacts of SPB relative to changes to fuel structure and composition generated by suppression management activities. Our results demonstrate short-term effects of SPB and suppression management. Given the limited experience with SPB in these forests and the results of this study, further research on fire behavior effects and patterns of stand development over the long-term are needed.

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4

Satterlee, Sarah Melissa. "Evolution of the southern pine beetle legacy simulation model "SPBMODEL" using genetic algorithms." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35907.

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SPBMODEL, a legacy southern pine beetle (SPB) simulation model, was translated into a new JavaTM model called Javahog. The Javahog output was verified to be essentially identical to SPBMODEL output by means of standard and paired t-tests. Javahog was placed online and is currently accessible via a servlet. Genetic algorithms (GAs) were applied to the Javahog model. GAs are a type of optimization heuristic that operate as an analog to evolution. GAs "evolve" a very good solution to a complex problem. In this case, GAs were intended to evolve a very good version of SPBMODEL. GAs were applied in part to improve upon the SPBMODEL design, and in part to demonstrate that GAs are effective tools for recalibrating legacy simulation models. Beyond simply recalibrating model parameters, the GA was used to select optimal functional forms for the development rates of each SPB life stage. The GA evolved a model that performed better than SPBMODEL at predicting observed field data, according to a balanced fitness function and according to sums of squared errors. However, from a visual comparison of the output of both models versus observed field data, neither model achieved satisfactory performance.
Master of Science

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5

Grosman, Donald Michael. "Southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae) : quantitative analysis of chiral semiochemicals /." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-05042006-164540/.

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6

McManis, Anne Elise. "Phenology of a Southern Population of Mountain Pine Beetle (Dendroctonus ponderosae)." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7006.

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Mountain pine beetle (Dendroctonus ponderosae, Hopkins) is a major disturbance agent in pine ecosystems of western North America. Adaptation to local climates has resulted in primarily univoltine (one generation per year) generation timing across a thermally diverse latitudinal gradient. We hypothesized that this pattern in total development time is shaped by selection for slower developmental rates, altered developmental thresholds, or oviposition rates in southern populations inhabiting warmer climates. To investigate traits responsible for latitudinal differences we measured lifestage-specific development of southern mountain pine beetle eggs, larvae and pupae across a range of temperatures. We also describe and model oviposition of southern US MPB. Using a novel technique that included frequent X-ray imaging, oviposition rate and fecundity were estimated separately and shown to both be significant and independent sources of variation. When compared with previously collected data for a northern MPB population, total oviposition time predicted for southern MPB at a constant 20°C was slightly longer than that of northern MPB, but the delay was too small to account for significant differences between the populations in total development time. Developmental rate curves for eggs, larvae, and pupae were fit using maximum posterior likelihood estimation with a Bayesian prior to improve fit stability. When compared to previously published data for a northern population (Régnière et al. 2012), observed developmental rates of the southern and northern populations were similar across all studied lifestages at 20 and 25°C, although southern individuals were generally faster at temperature extremes (10 and 27°C). These findings were inconsistent with our hypothesis that southern individuals would have consistently slower rates. Optimal development of southern individuals occurred at higher temperatures, with higher development thresholds, as compared with northern individuals. Our results suggest that evolved traits in the remaining unstudied lifestage, teneral (i.e., pre-emergent) adult, likely influence latitudinal differences in mountain pine beetle generation time.

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7

Moan, Jason Edward. "Development and assessment of remotely derived variables in current southern pine beetle (Dendroctonus frontalis Zimm.) hazard mapping in North Carolina, USA." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/34618.

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The southern pine beetle (SPB) (Dendroctonus frontalis Zimm.) is one of the most destructive forest insect pests in the southeastern United States and has historically had a large impact on the forests of North Carolina. Many characteristics of a forest can contribute to SPB susceptibility including stand density, growth rate, age, soil type, and position on the landscape. This work was undertaken in an effort to assist and improve on the current federal SPB hazard modeling being conducted for North Carolina by the USDA Forest Service â Forest Health Protectionâ s Forest Health Technology Enterprise Team (FHTET). In our study, predictive SPB susceptibility models were developed for each physiographic region in North Carolina using two variables not currently included in the FHTET modeling, mean stand age and the in-stand percentage of sawtimber-sized pines. These variables were obtained from USDA Forest Service â Forest Inventory and Analysis (FIA) data and North Carolina Forest Service historical SPB records creating a dataset of both infested and non-infested stands and the models were developed using the CARTÂ® classification tree approach. Two model-derived age classes (older than and younger than 22 years) were identified on the landscape using current Landsat 5 Thematic Mapper (TM) imagery chronosequences of disturbance index (DI) â transformed scenes to identify stand-replacing disturbances, resulting in a kappa statistic of 0.6364 for the younger than 22 year age class and 0.7778 for the older than 22 years age class. A kappa value of 1 is ideal. The CARTÂ® modeling effort produced valid models in all three physiographic regions of North Carolina, though the complexity of the piedmont model makes it impractical for use in the field. The dependent variable in the classification tree was presence or absence of SPB outbreak and the test sample error percentages were similar across regions, with errors ranging between 23.76 - 34.95 percent. Overall prediction success, based on the softwareâ s internal cross-validation procedure, was likewise comparable across the regions with 72.28 - 89.56 percent correctly predicted. Based on our modeling, stand age and percent sawtimber should be included in future FHTET SPB hazard modeling efforts for the coastal plain and mountains, respectively. Age classes can be reasonably estimated using Landsat or other multispectral imagery.
Master of Science

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8

Watson, Adam. "Cost share payment and willingness to participate in Virginia's Pine Bark Beetle Prevention Program." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32876.

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Forest management practices which reduce southern pine beetle (SPB) risk benefit not only the landowners who perform them, but all those who draw benefits from southern pine forests in Virginia, especially other forest owners within the same region. One such management practice is pre-commercial thinning (PCT), which is particularly unattractive to non-industrial private forest (NIPF) landowners because of the substantial costs and delayed financial returns involved. Since the benefits to society generated by PCT are not fully realized by the individuals who might implement it, there may be a market externality in which PCT is underprovided across the landscape. The Pine Bark Beetle Prevention Program (PBBPP) has the potential to correct this externality by reimbursing a portion of the costs of PCT for landowners who qualify. However, cost share incentives have been criticized for being ineffectual on the basis that landowners substitute publicly funded reimbursement for private investment, without altering their management practices. To investigate the effect of the PBBPP cost share for PCT, a survey was sent to 1,200 NIPF landowners in seven counties across the Piedmont and Coastal Plain physiographic regions of Virginia, where southern pine is prevalent and SPB hazard is a relevant concern. To measure willingness to participate in the program, a referendum style question was used in which the offered cost share ranged from 20% to 90%. Results of discrete choice models estimated from survey data indicate that cost sharing has a significant, positive effect on willingness to participate overall, though increasing reimbursement above 60% is unlikely to affect participation. Some landowners are not responsive or are less responsive to cost sharing due to personal and property characteristics.
Master of Science

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9

Ryall, Krista Lee. "Biology of the recently introduced pine shoot beetle Tomicus piniperda (L.) (Coleoptera, scolytidae) in Southern Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0010/MQ29358.pdf.

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10

Hailu, Solomon Ghebremeskel. "THE EFFECT OF HABITAT FRAGMENTATION ON THE SPATIAL POPULATION GENETIC STRUCTURE OF SOUTHERN PINE BEETLE (DENDROCTONUS FRONTALIS)." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/624.

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Southern pine beetle (SPB), Dendroctonus frontalis (Zimmerman), is one of the most destructive insect pests of pine trees in southern United States, Mexico and Central America. There is relatively little information on the effect of habitat fragmentation on the connectivity and the spatial population genetics of SPB. This study therefore, adds to previously generated information by assessing how habitat fragmentation affects the spatial population genetic structure of SPB. It also introduces a new approach to the study of bark beetle population dynamics by assessing how landscape variables shape their effective dispersal. To address this issue, a suite of eight highly polymorphic DNA microsatellite markers were used to measure SPB movement over a representative range of SPB habitat and non-habitat (matrix). At the broadest scale, highly significant genetic differentiation suggests that the sampled populations are not panmictic. Loci with higher variability yielded higher resolution for both the infinite allele model based measure of differentiation (FST) and the stepwise mutation based measure (RST) estimates. It is apparent that allelic frequency differences, allelic size ranges and repeat motif played a role in the observed patterns of pair-wise differentiations between the sampled localities. It is supposed that gene flow, wide-range dispersal and recent divergent time could have contributed to the lower level of genetic structure observed in the pair wise estimates. The sampled populations did not show any differentiation attributable to the host species from which they were collected. Mantel test of genetic distance and Euclidean geographic distance revealed no correlation. Mantel tests of the correlation between genetic distance and cost weighted Euclidean distances also suggest that dispersal of SPB across geographic barriers is not significantly reduced. Thus, landscape features and host preference do not appear to have had an impact on population genetic structure of SPB. Since movements of these beetles were not significantly hindered by environmental factors like major rivers, roads, elevation and host type, it is advisable for regional pest management offices to put an effort and coordinate their prevention and management plans in a broader scale to alleviate the problem associated with this native insect pest. Disequilibrium in the observed homogenized pattern of the beetle in this study suggests human contribution in the dispersal of SPB. Therefore, stringent control is deemed necessary in transportation of logs. This could improve our pest management system hence its positive implication in timber industry is obvious.

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11

Skordinski, Karen R. (Karen Renee). "Ecological Association Between the Red-Cockaded Woodpecker and Southern Pine Beetle in the Homochitto National Forest: a Geographic Information System Approach." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc279384/.

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Since the introduction of management practices by the Forest Service to stabilize red-cockaded woodpecker (RCW) populations, the number of cavity trees killed by southern pine beetles (SPB) has increased. A model of the landscape ecology of RCW and SPB in the Homochitto National Forest was created using data collected from the Forest Service and Global Atmospherics. The conclusions of the study were that the RCW and SPB utilize the same type of habitat and the stand hazard maps are an accurate means of determining the locations of SPB infestations. The functional heterogeneity maps created for the SPB and RCW would be useful predictors of future occurrences of either species if complete data were obtained.

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12

Jennings, David Scott. "Assessment of the potential role of blizzard damage in the spatial distribution of southern pine beetle infestation in Unicoi County, Tennessee." [Johnson City, Tenn. : East Tennessee State University], 2001. http://etd-submit.etsu.edu/etd/theses/available/etd-0401102-152014/restricted/JenningsD.041802.pdf.

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13

Jennings, David Scott. "Assessment of the Potential Role of Blizzard Damage in the Spatial Distribution of Southern Pine Beetle Infestation in Unicoi County, Tennessee." Digital Commons @ East Tennessee State University, 2002. https://dc.etsu.edu/etd/670.

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The Southern Pine Beetle, or SPB, (Dendroctonus frontalis Zimmerman) is a bark beetle that is endemic to the Southern forest ecosystem. Beetle populations remain stable for years at a time; however, for reasons not fully understood the beetle undergoes accelerated population growth on approximate ten-year cycles, culminating in increased beetle activity. Although most trees can withstand a beetle assault when populations are reduced, healthy trees, and even pine species that are not generally attacked can become a host tree for millions of beetles during infestations. Much of Appalachia was paralyzed by an unusually heavy snowstorm on January 27, 1998, resulting in major power failures and tremendous tree damage. Environmental hazards such as this storm have historically been a factor with southern pine beetle populations. This study hypothesizes that the blizzard of January 27, 1998, significantly increased the southern pine beetle population. The evidence, however, did not support this hypothesis.

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14

Christel, Lynne M. "Distribution Parameters of Dendroctonus frontalis in a Georgia Landscape." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202713.

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A three-phase study was performed to examine abiotic and biotic metrics at southern pine beetle infestation sites in northern Georgia in 2002 to find early indicators that can be leveraged by forest managers to mitigate the effects of future outbreaks: creation of a 2003 Final Impact Map, determining if MODIS MOD13Q1 EVI 16-day image composites can distinguish differences in biomass indicators among healthy and infested loblolly pine and hardwood forests, and creation of an Infestation Risk Map derived from significant climate and physical variables at known infestation sites.Three land cover classification techniques (change vector analysis, enhanced wetness differencing index and standard land cover classification analysis of Landsat 5 TM) were compared to determine which would provide the best estimate of final infestation damage. Classification accuracy results indicated that the latter provided the most reliable site damage information and it became the reference map against which outbreak model results were compared.Using time series analysis of MODIS composites acquired March 2000 - December 2006 to measure 11 phenology metrics for infested and healthy loblolly and hardwood stands showed that the imagery differentiated between forest classes. Results indicated the lowest base vegetation biomass in 2001 for infested loblolly, relative to healthy loblolly, with many metrics trending towards hardwood values following infestation.Abiotic influences included those related to landscape position and climate. Statistical testing showed increased beetle success: 1) along ridge tops at maximum solar exposure, 2) in areas with canopy density>60%, 3) in areas experiencing cooler summers and warmer winters, and 4) where precipitation was significantly lower at infested sites in the 2 years preceding outbreak.The Infestation Risk Map was developed from significant physical and climate indicator variables using the fuzzy theory modeling approach. Comparison of model output to infestation sites resulted in Chi-squared and Cramér's V values of 55.4 and 0.16, respectively, indicating that infestation risk distributions strongly paralleled site infestation. Comparison of model output and low, medium and high infestation density clusters resulted in Chi-squared and Cramér's V values of 241.24 and 0.66, respectively, indicating a more substantive relationship between infestation density and risk classes.

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15

Valiev, Abduvali. "Enzymology." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608217/index.pdf.

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In this study, two symbiotic fungi of Southern Pine Beetle (SPB), Entomocorticium peryii and Entomocorticium sp.A were evaluated in terms of polyphenol oxidase (PPO) production. The effect of different inhibitors, inducers and assay parameters such as temperature and pH on enzyme activity were investigated and maximum PPO activity was observed at 30°
C, pH 8.0 and when tannic acid was used as an inducer. Copper-chelator salicyl hydroxamic acid (SHAM) and pcoumaric acid, both indicated as inhibitors of tyrosinase and catechol oxidase significantly reduced the activity. For biochemical characterization studies, the enzyme was concentrated by ultrafiltration. To determine type of the enzyme, activity staining after Native-PAGE was carried out. Type of polyphenol oxidase produced by E. peryii and E. sp.A was determined as catechol oxidase by activity staining. However higher activity was observed on hydroquinone (p-diphenol) rather than catechol (o-diphenol). The enzyme obeys Michealis-Menten kinetics with Km and Vmaxvalues being 10.72 mM hydroquinone and 59.44 U/ml for E. peryii and 8.55 mM hydroquinone and 73.72 U/ml for E. sp.A respectively..

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16

Duehl, Adrian Joseph. "Predicting southern pine beetle infestation risk from neighborhood history and environmental conditions." 2008. http://www.lib.ncsu.edu/theses/available/etd-03182008-094036/unrestricted/etd.pdf.

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17

Stukey, Jared D. "Deriving a Framework for Estimating Individual Tree Measurements with Lidar for Use in the TAMBEETLE Southern Pine Beetle Infestation Growth Model." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7632.

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The overall goal of this study was to develop a framework for using airborne lidar to derive inputs for the SPB infestation growth model TAMBEETLE. The specific objectives were (1) to estimate individual tree characteristics of XY location, individual bole height (IBH), diameter at breast height (DBH), length of crown (CrHT), and age for use in TAMBEETLE; (2) to estimate individual tree age using lidar-estimated height and site index provided by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey Geographic Database (SSURGO); and (3) to compare TAMBEETLE simulation results using field measurements and lidarderived measurements as inputs. Diameter at breast height, individual bole height, and crown length were estimated using lidar with an error for mean measurements at plot level of 0.16cm, 0.19m, and 1.07m, respectively. These errors were within root mean square error (RMSE) for other studies at the study site. Age was estimated using the site index provided by SSURGO and the site index curves created for the study area with an RMSE of 4.8 years for mean plot age. Underestimation of tree height by lidar and error in the site index curve explained 91% of the error in mean plot age. TAMBEETLE was used to compare spot growth between a lidar-derived forest map and a forest map generated by TAMBEETLE, based on sample plot characteristics. The lidar-derived forest performed comparably to the TAMBEETLE generated forest. Using lidar to map forests can provide the large spatial extents of the TAMBEETLE generated forest while maintaining the spatially explicit forest characteristics, which were previously only available through field measurements.

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18

Novick, Kimberly Ann. "Reducing Uncertainty in The Biosphere-Atmsophere Exchange of Trace Gases." Diss., 2010. http://hdl.handle.net/10161/2984.

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A large portion of the anthropogenic emissions of greenhouse gases (GHGs) are cycled through the terrestrial biosphere. Quantifying the exchange of these gases between the terrestrial biosphere and the atmosphere is critical to constraining their atmospheric budgets now and in the future. These fluxes are governed by biophysical processes like photosynthesis, transpiration, and microbial respiratory processes which are driven by factors like meteorology, disturbance regimes, and long term climate and land cover change. These complex processes occur over a broad range of temporal (seconds to decades) and spatial (millimeters to kilometers) scales, necessitating the application of simplifying models to forecast fluxes at the scales required by climate mitigation and adaptation policymakers.

Over the long history of biophysical research, much progress has been made towards developing appropriate models for the biosphere-atmosphere exchange of GHGs. Many processes are well represented in model frameworks, particularly at the leaf scale. However, some processes remain poorly understood, and models do not perform robustly over coarse spatial scales and long time frames. Indeed, model uncertainty is a major contributor to difficulties in constraining the atmospheric budgets of greenhouse gases.

The central objective of this dissertation is to reduce uncertainty in the quantification and forecasting of the biosphere-atmosphere exchange of greenhouse gases by addressing a diverse array of research questions through a combination of five unique field experiments and modeling exercises. In this first chapter, nocturnal evapotranspiration -- a physiological process which had been largely ignored until recent years -- is quantified and modeled in three unique ecosystems co-located in central North Carolina, U.S.A. In the second chapter, more long-term drivers of evapotranspiration are explored by developing and testing theoretical relationships between plant water use and hydraulic architecture that may be readily incorporated into terrestrial ecosystem models. The third chapter builds on this work by linking key parameters of carbon assimilation models to structural and climatic indices that are well-specified over much of the land surface in an effort to improve model parameterization schemes. The fourth chapter directly addresses questions about the interaction between physiological carbon cycling and disturbance regimes in current and future climates, which are generally poorly represented in terrestrial ecosystem models. And the last chapter explores effluxes of methane and nitrous oxide (which are historically understudied) in addition to CO₂ exchange in a large temperate wetland ecosystem (which is an historically understudied biome). While these five case studies are somewhat distinct investigations, they all: a) are all grounded in the principles of biophysics, b) rely on similar measurement and mathematical modeling techniques, and c) are conducted under the governing objective of reducing measurement and model uncertainty in the biosphere-atmosphere exchange of greenhouse gases.

Dissertation

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19

"Assessment of the Potential Role of Blizzard Damage in the Spatial Distribution of Southern Pine Beetle Infestation in Unicoi County, Tennessee." East Tennessee State University, 2002. http://etd-submit.etsu.edu/etd/theses/available/etd-0401102-152014/.

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20

Dordel, Julia. "Influences of mountain pine beetle (Dendroctonus ponderosea), fire, and ungulate browsing on forest stand structure in the southern Canadian Rocky Mountains." Thesis, 2005. http://hdl.handle.net/2429/16434.

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Forests in the montane and lower subalpine ecoregions of the southern Canadian Rocky Mountains may have been more open and structurally diverse at the beginning of the 20th century than today. Today, mature Pinus contorta var. latifolia Dougl. (lodgepole pine) causing mountain pine beetle (MPB, Dendroctonus ponderosae) infestations, infrequent high severity fires, and herbivory appear to have increased in Banff and Kootenay National Parks. Based on a review of the literature it was hypothesised that 1. MPB infestations increase forest stand structural diversity; 2. Browsing intensity decreases with increasing amounts of coarse woody debris; and 3. Disturbances such as MPB infestation and low severity fire lead to decreased MPB stand susceptibility. Stand structure parameters were investigated in mesic montane and lower subalpine stands 15, 25, and 65 years after MPB outbreaks. Parameters measured were tree density, diameter, height class, species, and age distributions as well as coarse woody debris mass. Also, influences of fire frequency, time since fire and fire severity on the current stand structure were analysed. A MPB susceptibility index was calculated for stands with different MPB and fire disturbance histories. The Shannon-Wiener index indicated higher stand structural diversity on plots 15 years but not 25 and 65 years after MPB infestations. Influences of fire on stand structure were limited to increasing tree density with increasing time since the stand initiation fire, and higher proportions of understory vegetation at lower fire severities. Also, there was an indication that high amounts of coarse woody debris resulted in reduced browsing intensity. Finally, the MPB susceptibility index was significantly lower on stands with previous MPB infestations. The MPB susceptibility index also tended to be lower with increasing number of fires. Consequently, none of the above hypothesis could be rejected. Low intensity fires and a reduction of herbivory might be crucial to promote other early successional species such as Populus tremuloides (trembling aspen). Management strategies allowing for MPB and fire disturbances would benefit the ecosystems in the study area.
Forestry, Faculty of
Graduate

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Dissertations / Theses on the topic 'Southern Pine Beetle'

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