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- Disturbance (3)
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Articles 1 - 23 of 23
Full-Text Articles in Life Sciences
Insights Into The Challenges Posed By Climate Change And Land Competition To Brazil’S Midwest Pulpwood Market, Roberto Hajime Sant Anna Kimura
Insights Into The Challenges Posed By Climate Change And Land Competition To Brazil’S Midwest Pulpwood Market, Roberto Hajime Sant Anna Kimura
Theses and Dissertations
I investigated the effect of climate change in one of the few expanding markets in the world in Brazil. In the last decades the demand for pulpwood increased from zero to 11 million tons, leading to an expansion of 700 thousand hectares of Eucalyptus plantation. In 2024, a new mill will start operating increasing the consumption of wood fiber by 8.2 million tons (+49%). I used mathematical programming to investigate how different scenarios of productivity and land will affect the market. My results showed that around 946,000 hectares (+124%) of additional timberland will be necessary in the upcoming decades. The …
A Silvicultural Approach To Increase Drought Resistance And Resilience In Longleaf Pine, Kyle R. Dues
A Silvicultural Approach To Increase Drought Resistance And Resilience In Longleaf Pine, Kyle R. Dues
Theses and Dissertations
Droughts are a common disturbance experienced by forest systems across the southeastern United States and are expected to increase in frequency in the near future. Few empirical studies have evaluated the response of individual tree resistance and resilience following silvicultural treatment in longleaf pine (Pinus palustris Mill.). This study evaluates the differences in drought responses between two forests during three different periods. The first period evaluated pretreatment (2000) conditions, while the second (2006), and third (2011) compared conditions after the implementation of five silvicultural treatments. The main findings are that, as additional basal area is removed, both individual tree …
Timing Is Everything: Impacts Of Firing Technique And Season On Plant Communities In The Southeastern United States, Luke Michael Resop
Timing Is Everything: Impacts Of Firing Technique And Season On Plant Communities In The Southeastern United States, Luke Michael Resop
Theses and Dissertations
Prescribed fire is a common land management tool in the southeastern United States. Historical fires occurred primarily in the growing season, but modern day prescribed fire is commonly restricted to the dormant season. Plant community responses to various fire regimes are relatively unknown, and managers require information on how fire regimes impact plant communities. To address these limitations, I studied the impacts of March and June fire on plant communities. Results indicated various woody midstory species respond differently to fire season and community response is driven by species composition. In another study, I examined impacts of February, May-June, and September-October …
Maximum Size-Density Relationships In Mixed-Species And Monospecific Stands Of The Southeastern United States, Maxwell Robert Schrimpf
Maximum Size-Density Relationships In Mixed-Species And Monospecific Stands Of The Southeastern United States, Maxwell Robert Schrimpf
Theses and Dissertations
Maximum size-density relationships (MSDR) are used to quantify differences across sites in the number of trees of a given size and species that can be supported per hectare. These relationships are important to managers who are trying to maximize basal area and wood volume. In my study, I examined MSDR across Alabama, Georgia, Louisiana, and Mississippi using US Forest Service, Forest Inventory and Analysis (FIA) data. I determined the impact of species-specific, specific gravity, functional traits, and environmental factors on MSDR using a quantile regression approach. Overall, I found that climatic factors had the greatest influence on MSDR, and that …
Modeling The Effect Of Neighborhood Competition On Tree Diameter Growth In The Pacific Northwest Coast Range, Htet Lin Naing
Modeling The Effect Of Neighborhood Competition On Tree Diameter Growth In The Pacific Northwest Coast Range, Htet Lin Naing
Theses and Dissertations
Trees compete for various resources such as sunlight, water, and nutrients, which can be expressed as numerical terms, called competition indices (CI). Competition between individual trees is correlated with their growth and mortality. Therefore, CIs are used as independent variables to develop, improve and modify growth and yield models. This study was conducted to test the effect of neighborhood competition on tree diameter growth among Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg) and red alder (Alnus rubra Bong.), in the Pacific Northwest Coast Range, USA. After testing seven distance-independent CIs and three distance-dependent …
Gene Expression Effects On Productivity And Stress Tolerance In Polyclonal Plantings Of Populus Deltoides, Macy Gosselaar
Gene Expression Effects On Productivity And Stress Tolerance In Polyclonal Plantings Of Populus Deltoides, Macy Gosselaar
Theses and Dissertations
Polyclonal plantings of Populus deltoides are expected to display increased site resource use, productivity, and tolerance to stress through plasticity changes leading to niche differentiation (i.e changes to crown/canopy structures). In the present study, P. deltoides Clones S7C8, 110412, and polyclonal plots were tested for differentially expressed genes and enriched biological pathways between planting schemes. Transcriptomic analysis of leaves revealed upregulation of an active growth gene and gene family members that play important roles in plant stress and stress tolerance in polyclonal plantings. A gene associated with oxidative stress was upregulated in polyclonal plantings across all treatments. Secondary metabolic pathways …
Leaf Area Index And Aboveground Biomass Estimation Of Populus And Its Hybrids Using Terrestrial Lidar, Surya Adhikari
Leaf Area Index And Aboveground Biomass Estimation Of Populus And Its Hybrids Using Terrestrial Lidar, Surya Adhikari
Theses and Dissertations
Short rotation woody crops (SRWC) eastern cottonwood (Populus deltoides) and hybrid poplar plantations were established in 2021 in Pontotoc and Oktibbeha counties of Mississippi to study the biomass potential of SRWC for biofuel production. We used a novel backpack LiDAR system to measure forest metrics and harvested sample trees to build aboveground biomass (AGB) and leaf area index (LAI) equations. The results showed that LiDAR-derived variables accurately estimated aboveground biomass (R2 =0.81 and 29.22 % RMSE). However, the LAI estimation results showed that the LiDAR metrics moderately explained field measurements of LAI (R2 =0.31 and 18.05% …
Spatial Conservation Planning In The Southeastern United States: Alignments And Opportunities, Bradly Stewart Thornton
Spatial Conservation Planning In The Southeastern United States: Alignments And Opportunities, Bradly Stewart Thornton
Theses and Dissertations
Conservation managers and planners need the ‘best available science’ to support robust and defensible decisions, ensuring that public resources are appropriately allocated. Spatial planning products and decision-support tools developed for this purpose should enable partner organizations to achieve focus, coordination, and increased effectiveness in their investments and actions. Whereas conservation partnerships have historically created distinct planning tools, there is increasing interest for improved coordination, communication, and unifying biological datasets to improve the cohesiveness of regional management activities. We sought to inform spatial conservation planning efforts in the southeastern United States through the development of species distribution models for focal avian …
The Response Of An Avian Community To Intercropping And Forest Management Practices In A Private Working Pine Forest, Rebecca Doyne Bracken
The Response Of An Avian Community To Intercropping And Forest Management Practices In A Private Working Pine Forest, Rebecca Doyne Bracken
Theses and Dissertations
Within managed pine forest systems, a plethora of bird species exist throughout the lifecycle of a stand akin to what may be experienced through post-disturbance regeneration in a natural forest system. I sought to address how breeding avian communities shift across time in response to stand aging and forest management, evaluate species-specific responses to stand conditions, investigate the responses of at-risk avian species to forest management, and determine avian non-breeding, over-wintering presence in a managed loblolly pine (Pinus taeda) forest. I conducted breeding bird point count and vegetation surveys within five stands of privately owned and managed pine forest in …
Patterns, Mechanisms, And Characterization Of Carbon Cycling Stability Following Partial Forest Disturbance, Kayla C. Mathes
Patterns, Mechanisms, And Characterization Of Carbon Cycling Stability Following Partial Forest Disturbance, Kayla C. Mathes
Theses and Dissertations
Among the most essential questions in the era of climate change is how the forest carbon (C) cycle will respond to an increase in the extent of biotic disturbances from insects and pathogens. While research has focused on stand-replacing disturbance regimes, less is known about C cycling stability following partial disturbances that produce gradients of disturbance severity. Belowground C cycling responses to disturbance are especially poorly understood, even though temperate forest soils contain up to 50% of total ecosystem C and soil respiration (Rs) accounts for more than half of temperate forest C loss. Interpreting trends and mechanisms …
Mapping Forest Structure In Mississippi Using Lidar Remote Sensing, Nitant Rai
Mapping Forest Structure In Mississippi Using Lidar Remote Sensing, Nitant Rai
Theses and Dissertations
This study aimed at evaluating the agreement of spaceborne Light Detection and Ranging (lidar) ICESat-2 canopy height with Airborne Laser Scanning (ALS) derived canopy height to inform about the performance of ICESat-2 canopy height metrics and understand its uncertainties and utilities. The agreement was assessed for different forest types, physiographic regions, a range of percent canopy cover, and diverse disturbance histories. Results of this study suggest that best agreements are found using strong beam data collected at night for canopy height retrieval using ICESat-2. The ICESat-2 showed great potential for estimating canopy heights, particularly in evergreen forests with high canopy …
Evaluating Functional Zoning Based On Site Index To Achieve Competing Objectives Held By Family Forest Owners On Southern U.S. Pine Forest Tracts, Bradley S. Resch
Evaluating Functional Zoning Based On Site Index To Achieve Competing Objectives Held By Family Forest Owners On Southern U.S. Pine Forest Tracts, Bradley S. Resch
Theses and Dissertations
Family forests comprise a significant portion of total forest lands in the southern United States and their owners frequently have multiple, competing objectives. This research evaluated the effectiveness of functional zoning based on site index on forest sizes relevant to family forest owners. A total of fifty family forests were randomly selected from counties in the East Texas Pineywoods region. Timber production and quail habitat were used as proxies for competing objectives. It was found that 80% of family forest parcels had sufficient site index heterogeneity to benefit from functional zoning. For forest parcels that could benefit from functional zoning, …
Novel Silviculture Practices For Non-Industrial Private Forest Landowners, Darcey Alyce Collins
Novel Silviculture Practices For Non-Industrial Private Forest Landowners, Darcey Alyce Collins
Theses and Dissertations
Many landowners in the southeastern United States have invested in southern yellow pine plantations and managed them using traditional management schemes. However, non-industrial private forest landowners often have goals and challenges that make traditional management less desirable or possible. This thesis contains two projects that offer potential solutions for these landowners. The first project is a management option for landowners with small parcels that wish to manage pine plantations and proposes low-density management paired with crown lifting for the production of saw logs without commercial thinning entries. The second proposes a method for incorporating mixed-species management into already existing plantations. …
Use Of Consumer Grade Small Unmanned Aerial Systems (Suas) For Mapping Storm Damage In Forested Environments, James Dewey Cox
Use Of Consumer Grade Small Unmanned Aerial Systems (Suas) For Mapping Storm Damage In Forested Environments, James Dewey Cox
Theses and Dissertations
Storm damages to forested environments pose significant challenges to landowners, land managers, and conservationists alike. Damage scope and scale assessments can be difficult, costly, and time consuming with conventional pedestrian survey techniques. Consumer grade sUAS technology offers an efficient, cost-effective way to accurately assess storm damage in small to moderate sized survey areas (less than 10 km²). Data were collected over a 0.195 km² area of damaged timber within the Kisatchie National Forest in Central Louisiana using a DJI Mavic 2 Pro drone. Collected imagery was processed into an orthomosaic using Agisoft Metashape Professional with a resulting ground sampling distance …
Diversity-Productivity Relationships In Forests Of The Southeastern United States: Leveraging National Inventory Data And Tree Functional Traits, Elizabeth Baach
Diversity-Productivity Relationships In Forests Of The Southeastern United States: Leveraging National Inventory Data And Tree Functional Traits, Elizabeth Baach
Theses and Dissertations
Numerous studies have evaluated the relationship between biodiversity and productivity, with general trends suggesting a positive relationship. While most studies only use species richness, this study also analyzed how productivity changes with functional diversity and Shannon’s diversity index. Functional diversity gives important context to the examination of biodiversity-productivity relationships due to the direct link between organisms’ functional traits and their role in a given ecosystem. This study used data from the USDA Forest Service Forest Inventory and Analysis (FIA) database collected in Alabama, Louisiana, and Mississippi to estimate plot-level productivity and diversity. Structural equation modeling was used to determine the …
Assessing Priority Bird Response To Open Pine Management In Eastern Mississippi, Holly Marie Todaro
Assessing Priority Bird Response To Open Pine Management In Eastern Mississippi, Holly Marie Todaro
Theses and Dissertations
Fire suppression, combined with lack of forest thinning and short-rotation, monodominant management, has drastically altered the landscape in the southeastern U.S., leading to the loss of open pine ecosystems and associated avian species. Management of open pine ecosystems is a common practice; yet, there remains uncertainty regarding how vegetation structure impacts priority species. Using empirical data, I assessed changes in species abundance and associated vegetation characteristics before and after management. I also sought to identify vegetation characteristics that influence home range establishment and microhabitat selection of Bachman’s Sparrows. Priority species were negatively associated with hardwood midstory and abundance per site …
Climate Sensitive Diameter Growth Models For Major Tree Species In Mississippi, Sujan Subedi
Climate Sensitive Diameter Growth Models For Major Tree Species In Mississippi, Sujan Subedi
Theses and Dissertations
Anticipated climate change and increasing wood demand require dependable diameter growth models for adaptive forest management. We used a mixed-effects modeling approach with Forest Inventory and Analysis (FIA) data to fit diameter growth models for loblolly pine, other softwood species (slash pine, shortleaf pine, and longleaf pine), sweetgum, and other hardwood (southern red oak, red maple, and water oak) species. Climatic variables coupled with individual tree attributes and competition factors improved climate insensitive models. Growth of loblolly pine and sweetgum was positively correlated with mean temperature of the coldest month. Mean temperature of the warmest month negatively influenced diameter growth …
Variation In Personality Among Semi-Wild Myanmar Timber Elephants, Sateesh Venkatesh
Variation In Personality Among Semi-Wild Myanmar Timber Elephants, Sateesh Venkatesh
Theses and Dissertations
This study examines two personality traits: exploration and neophobia, which could influence human-elephant conflicts. Thirty-one semi-wild elephants were tested over two trials using a custom novel puzzle tube containing three tasks and three rewards. Our studies show that elephants do vary significantly between individuals in both exploration and neophobia.
Senescent Trees Stabilize Aboveground Wood Net Primary Production Immediately After Disturbance, Maxim S. Grigri
Senescent Trees Stabilize Aboveground Wood Net Primary Production Immediately After Disturbance, Maxim S. Grigri
Theses and Dissertations
In the United States, forests sequester 17% of national carbon (C) emissions annually (UGCRP, 2018), however shifting forest disturbances threaten the stability of this essential C sink. Unlike the high severity, stand-replacing disturbances that were widespread a century ago, today’s eastern temperate forests experience frequent low-to-moderate severity disturbances from invasive pests and pathogens with mixed effects on net primary production (NPP). Carbon cycling stability after disturbance has been reported, however, the mechanisms underlying immediate NPP stability or decline are not well understood. Through weekly measurements of production in a landscape scale experiment, we show that the sustained growth of senescent …
Natural And Anthropogenic Drivers Of Tree Evolutionary Dynamics, Brandon M. Lind
Natural And Anthropogenic Drivers Of Tree Evolutionary Dynamics, Brandon M. Lind
Theses and Dissertations
Species of trees inhabit diverse and heterogeneous environments, and often play important ecological roles in such communities. As a result of their vast ecological breadth, trees have become adapted to various environmental pressures. In this dissertation I examine various environmental factors that drive evolutionary dynamics in threePinusspecies in California and Nevada, USA. In chapter two, I assess the role of management influence of thinning, fire, and their interaction on fine-scale gene flow within fire-suppressed populations of Pinus lambertiana, a historically dominant and ecologically important member of mixed-conifer forests of the Sierra Nevada, California. Here, I find evidence …
Ash Tree Identification Based On The Integration Of Hyperspectral Imagery And High-Density Lidar Data, Haijian Liu
Ash Tree Identification Based On The Integration Of Hyperspectral Imagery And High-Density Lidar Data, Haijian Liu
Theses and Dissertations
Monitoring and management of ash trees has become particularly important in recent years due to the heightened risk of attack from the invasive pest, the emerald ash borer (EAB). However, distinguishing ash from other deciduous trees can be challenging. Both hyperspectral imagery and Light detection and ranging (LiDAR) data are two valuable data sources that are often used for tree species classification. Hyperspectral imagery measures detailed spectral reflectance related to the biochemical properties of vegetation, while LiDAR data measures the three-dimensional structure of tree crowns related to morphological characteristics. Thus, the accuracy of vegetation classification may be improved by combining …
The Effects Of Disturbance And Species Specific Interactions On Diversity In An Agent Based Forest Simulation, Matthew E. Mills
The Effects Of Disturbance And Species Specific Interactions On Diversity In An Agent Based Forest Simulation, Matthew E. Mills
Theses and Dissertations
In ecology literature, there is much data which suggests that conspecific negative density dependence (CNDD) and abiotic disturbances increase biodiversity in forests. This thesis elucidates the notion that not only do these two forces increase diversity, but they may also interact with one another in order to achieve higher levels of biodiversity. Abiotic disturbances, like fires and hurricanes, can indirectly impact conspecific effects because when these forces remove individuals from the landscape, the role of the conspecific effects will change. The interaction of these two factors in biodiversity are explored in an agent based forest simulation through a resource surface. …
Forest Stand Structure And Primary Production In Relation To Ecosystem Development, Disturbance, And Canopy Composition, Cynthia M. Scheuermann
Forest Stand Structure And Primary Production In Relation To Ecosystem Development, Disturbance, And Canopy Composition, Cynthia M. Scheuermann
Theses and Dissertations
Temperate forests are complex ecosystems that sequester carbon (C) in biomass. C storage is related to ecosystem-scale forest structure, changing over succession, disturbance, and with community composition. We quantified ecosystem biological and physical structure in two forest chronosequences varying in disturbance intensity, and three late successional functional types to examine how multiple structural expressions relate to ecosystem C cycling. We quantified C cycling as wood net primary production (NPP), ecosystem structure as Simpson’s Index, and physical structure as leaf quantity (LAI) and arrangement (rugosity), examining how wood NPP-structure relates to light distribution and use-efficiency. Relationships between structural attributes of biodiversity, …