Forest Biology Commons^™

Silviculture For Coastal Forest Resilience: Promoting Forest Regeneration And Managing Invasive Plant Species, Ryan Bohannon

All Dissertations

Coastal forests of the southern United States and the ecosystem services they provide are threatened by an intensifying and interacting suite of disturbances associated with global change. Silvicultural strategies such as enrichment planting, invasive plant management, and browse mitigation treatments can enhance the resilience and adaptive capacity of forests to these threats by promoting sustainable regeneration and recruitment dynamics. To improve our understanding of coastal forest disturbance regimes and their impacts on forest stand dynamics, I conducted a systematic literature review of maritime forest disturbance ecology and identified coastal storms, ungulate browsing pressure, and invasive plants as primary disturbances shaping …

Testing The Intermediate Disturbance Hypothesis On Anthropogenic Pressure In Central Alabama, Gavin Terrell

Theses

Biodiversity is fundamental to maintaining ecosystem structure and function globally. Prior to the late 20th century, ecological theory generally predicted that biodiversity would be highest in systems experiencing minimal disturbance. However, Joseph H. Connell challenged this view with the Intermediate Disturbance Hypothesis (IDH), which posits that species diversity peaks at intermediate levels of disturbance and declines under conditions of both low and high disturbance. Although widely cited, the applicability of the IDH to natural systems remains debated, particularly in the context of anthropogenic disturbances and when diversity is measured beyond species richness alone.

This study evaluated the predictions of the …

The Role Of Forest Disturbance And Habitat Characteristics In Shaping Arthropod Ecology., Kane Alec Lawhorn

Electronic Theses and Dissertations

Disturbances in forests often generate dead wood, which is an important resource for a variety of arthropods. In tropical wet forests where fire is rare, lightning and branchfalls are common disturbances that create canopy gaps with associated large amounts of localized dead wood. By contrast, prescribed fire is a common disturbance in temperate forest that creates habitat heterogeneity and widely dispersed dead wood resources. The ecological effects of these disturbances on arthropod communities are largely unknown. This dissertation investigates how disturbance and habitat associations in both tropical and temperate forest shape arthropod ecology. Throughout, I primarily focus on beetles, ants, …

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 (R_s) accounts for more than half of temperate forest C loss. Interpreting trends and mechanisms …

Response Of Running Buffalo Clover (Trifolium Stoloniferum Muhl Ex. A. Eaton) To Herbaceous Competition And Transplanting In Monongahela National Forest, Ruben E. Sabella

Graduate Theses, Dissertations, and Problem Reports (ETD)

Running buffalo clover (RBC) is a rare perennial plant that grows throughout the American Midwest and the Appalachian Mountains. It requires disturbed forests to establish and proliferate. It has been suggested that, in the past, these conditions were created by buffalo; now logging operations maintain RBC populations. However, forest managers have been looking for ways to create suitable habitat for RBC that do not involve harvesting practices. This could help create new populations in areas that cannot be logged. Once established, competing vegetation might influence RBC abundance and flowering. This study seeks to quantify this influence by measuring the vegetation …

Coupled Structure-Function Responses To Disturbance: High Structural Complexity Resistance Supports Primary Production Resistance, Kerstin M. Niedermaier

Theses and Dissertations

The capacity of forests to resist structural change and retain material legacies–the biotic and abiotic resources that persist through disturbance–is crucial to sustaining ecosystem functioning after disturbance. However, the role of forest structure as both a material legacy and feature supporting carbon (C) cycling stability following disturbance has not been widely investigated. We used a large-scale disturbance manipulation to ask whether LiDAR-derived canopy structures as material legacies drive 3-year responses of NPP to a range of disturbance severity levels. As part of the Forest Resilience Threshold Experiment (FoRTE) in northern Michigan, USA we simulated phloem-disrupting disturbances at a range of …

The Impacts Of Maple Syrup Production On The Herbaceous Layer In Appalachian Hardwood Forests, Logan Scott Ferguson

Graduate Theses, Dissertations, and Problem Reports (ETD)

Vegetation data were collected from eight maple syrup farms (sugarbushes) and eight undeveloped maple-dominated sites to examine potential differences in understory plant communities due to disturbance effects. Understory plants were identified to the species level and percent cover of aboveground leaf-area for each species was estimated within 600 total quadrats. Overstory data and environmental data were collected to help determine if they had any effect on herbaceous-layer plant communities. Species richness, Shannon diversity, and Pielou’s evenness were calculated, with the analysis showing no significant differences between the site types. The absolute cover of plant functional groups was also compared between …

Forest Structural Complexity And Net Primary Production Resilience Across A Gradient Of Disturbance In A Great Lakes Ecosystem, Lisa T. Haber

Theses and Dissertations

Forests are an important component of the global carbon (C) cycle and contribute to climate change mitigation through atmospheric C uptake and storage in biomass and soils. However, the forest C sink is susceptible to disturbance, which modifies physical and biological structure and limits spatial extent of forests. Unlike severe, stand-replacing disturbances that reset forest successional trajectories and may simplify ecosystem structure, moderate severity disturbances may instead introduce complexity in ways that sustain net primary production (NPP), leading to the phenomenon of “NPP resilience.” In this study, we examined the linkage between disturbance severity and ecosystem biological and physical structural …

Decadal Vegetation Succession Along A Chronosequence Within Eucalyptus Obliqua Wet Forest, Southern Tasmania, Christine Dobbin

Independent Study Project (ISP) Collection

Southern Tasmania is home to fire dependent mixed forests, which, if not maintained, will eventually be replaced by the rainforest understorey. Wet eucalypt forest succession after disturbance events was investigated through floristic and vertical measurements of four north facing chronosequence plots with labels describing the age class of each, from regrowth to mature sites. This study was possible due to the establishment of permanent 50m x 50m plots in 2007 for longitudinal monitoring and subsequent illustration of forest dynamics following disturbance, including clearfell burns and wildfire. The contents of this report are the comparative analyses of the findings from the …

Toward An Improved Conceptual Understanding Of North American Tree Species Distributions, Paige E. Copenhaver-Parry

Faculty Publications - Department of Biological & Molecular Science

Species distributions have often been assumed to represent climatic limitations, yet recent evidence has challenged these assumptions and emphasized the potential importance of biotic interactions, dispersal limitation, and disturbance. Despite significant investigation into these factors, an integrated understanding of where and when they may be important is lacking. Here, we review evidence for the factors underlying the historical and contemporary distributions of North American tree species and argue that a cohesive conceptual framework must be informed by an understanding of species ecological and evolutionary history. We further demonstrate that available evidence offers little indication of a significant, independent influence of …

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

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, …

Nonstructural Carbohydrate Concentrations Of Pine Trees As A Function Of Evolutionary History, Joshua T. Mims

College of Graduate Studies: Theses & Dissertations

Nonstructural carbohydrates (NSC) can supply substrate during periods when current photosynthate is unavailable or inadequate to meet metabolic demands. I hypothesized that natural selection has favored higher nonstructural carbohydrate concentrations ([NSC]) in species that have an evolutionary history of frequent disturbance and tested this using three southern pine species that have evolved under a continuum of disturbance frequencies (evolutionary history of fire ~ longleaf > slash > loblolly). Stem and root samples were collected from 12 similar-sized individual trees of each species during time periods that reflect the annual minimum and maximum [NSC]. A modified colorimetric method was performed on the samples …

Invasion Of Exotic Earthworms Into Ecosystems Inhabited By Native Earthworms, P. F. Hendrix, G. H. Baker, M. A. Callaham Jr., G. A. Damoff, C. Fragoso, G. Gonzalez, S. W. James, S. L. Lachnicht, T. Winsome, X. Zou

Faculty Publications

The most conspicuous biological invasions in terrestrial ecosystems have been by exotic plants, insects and vertebrates. Invasions by exotic earthworms, although not as well studied, may be increasing with global commerce in agriculture, waste management and bioremediation. A number of cases has documented where invasive earthworms have caused significant changes in soil profiles, nutrient and organic matter dynamics, other soil organisms or plant communities. Most of these cases are in areas that have been disturbed (e.g., agricultural systems) or were previously devoid of earthworms (e.g., north of Pleistocene glacial margins). It is not clear that such effects are common in …

A Comparative Analysis Of Potential Nitrification And Nitrate Mobility In Forest Ecosystems, Peter M. Vitousek, James R. Gosz, Charles C. Grier, Jerry M. Melillo, William A. Reiners

Dartmouth Scholarship

Mobilization in a wide range of forest ecosystems were investigated through a combination of field and laboratory experiments.Trenched plot experiments were performed in 17 forests, and laboratory incubation studies of potential ammonium and nitrate production were made on soils from 14ofthese sites.

Influence Of Logging On Douglas Fir Beetle Populations, R R. Lejeune, L H. Mcmullen, M D. Atkins

The Bark Beetles, Fuels, and Fire Bibliography

All species of bark beetles of economic importance prefer to attack freshly-killed host material. Logging slash, wind-throw, and fire-killed timber provide ideal breeding grounds for bark beetles. A few species, mostly in the Dendroctonus group, are able to kill living trees. When beetles in the group, raised in preferred host material, cannot find any or enough freshly-killed trees, logs, or slash to enter, they may attack living trees. In the interior of British Columbia, infestations of the Douglas fir beetle can often be traced to logging disturbance.