Life Sciences Commons^™

Regeneration Response To Salvage Logging Following Tornado Disturbance, Colby K. Bosley-Smith

Electronic Theses and Dissertations

In an era of increasing natural disturbances, successful tree regeneration has grown more difficult to achieve. Salvage logging, a common management response to disturbance, may further impede regeneration success, although published literature currently remains inconclusive. In 2013, a rare tornado in northcentral Maine, USA, and subsequent salvage operation created three clear ‘treatments’ for evaluation of post-disturbance regeneration: blowdown, blowdown followed by salvage logging and an undisturbed control. In the summers of 2022 and 2023, (nine and ten) years post-tornado, we revisited this site to examine regeneration outcomes.

During the summer of 2022, we evaluated stand structure and regeneration success of …

Climate Interactions Drive Tree Physiology And Growth In A Northeastern Forest Ecotone, Alexandra M. Barry

Electronic Theses and Dissertations

Climate change is a threat to global forest ecosystems. In the northeastern United States, forest trees are facing rising temperatures and increasingly inconsistent moisture regimes. In addition to long-term changes in climate conditions, there is concern about the potential for more frequent and intense climate extremes, which can have severe and rapid negative effects on tree physiology and growth. Further, climate extremes may co-occur to produce a greater magnitude of effect than the sum of their parts, with a prominent example being hot droughts, which are increasing in occurrence and severity. The impact of these and other extreme climate interactions …

Quantitative Silviculture Of Northern Conifers, David G. Ray

Electronic Theses and Dissertations

Quantitative tools used to guide the management of important northern conifer species require updating and refinement to address changes in the contemporary resource and evolving objectives of ownership. This work builds on an extensive body of knowledge about stand density management and innovates some new approaches. In sum, the three chapters presented herein: 1) seek to strengthen and more fully articulate arguments for adopting relative density as a primary metric of stand density assessment, 2) quantify minimum stand densities to achieve full site occupancy and argue for more parity with treatment of maximum stand density, and 3) present an empirically …

Assessing The Long-Term Effects Of Natural Disturbance-Based Silvicultural On The Avian Assemblage At The Acadian Forest Ecosystem Research Program, Carl Pohlman

Electronic Theses and Dissertations

Active forest management alters the resources available to forest-obligate species. Large-scale intensive management practices where timber production is the primary objective can lead to notable ecological changes in forest ecosystems. A key concept of ecological forestry is to design forest management activities to emulate natural disturbance regimes as a way to maintain the ecological integrity of forests. The Acadian Forest Ecosystem Research Program (AFERP) was undertaken as an experimental demonstration of management reflective of the region’s disturbance regime, which typically produces small canopy gaps. AFERP includes nine research areas assigned to three silvicultural treatments: unharvested control, small gap (expanding-group selection …

Forest Disturbance And Occupancy Patterns Of Carnivores: Results Of A Large-Scale Field Study In Maine, Usa, Bryn E. Evans

Electronic Theses and Dissertations

Understanding trends in the abundance and distribution of carnivores is important at global, regional and local scales due to their ecological role, their aesthetic and economic value, and the numerous threats to their populations. Carnivores in Maine range from the American black bear (Ursus americanus), to numerous native mesocarnivore species, such as American marten (Martes americana), fisher (Pekania pennanti), coyote (Canis latrans), red fox (Vulpes vulpes), bobcat (Lynx rufus), Canada lynx (Lynx canadensis) and to two small weasel species (Mustela erminea and Neogale frenata). …

Understanding The Adhesion Mechanism In Mycelium-Assisted Wood Bonding, Wenjing Sun

Electronic Theses and Dissertations

The increasing environmental awareness has led to an increased interest in developing more sustainable materials as alternatives to petroleum-derived products. Among different nature-based products, fungal-mycelium-based bio-composites have gained considerable attention in various applications. Multiple materials with different densities and structures and potential applications can be fabricated by inoculating filamentous white-rot fungi in lignocellulosic materials and other substrates. Different from lower-density as-grown foam-like mycelium composites, higher-density mycelium-lignocellulosic panels have the potential to replace commercial particleboard and fiberboard bonded by petroleum-based resins. This kind of composite can be produced by directly adding heat and pressure to the low-density foams or by assembling …

Tree Responses To Moderate And Extreme Drought In The Northeastern United States, Ruth A. Van Kampen

Electronic Theses and Dissertations

Climate change is expected to lead to novel drought conditions in the Northeastern United States. Therefore, experimental studies that mimic these conditions are crucial to understand the potential impact on forests. Further, recent large scale dendrochronological studies suggest that spring and summer droughts may immediately impact tree growth while fall droughts may cause delayed impacts on growth the following growing season. Therefore, in this study, we investigated the impacts of six-week-long spring, summer, and fall droughts on the physiology and intra-annual growth on 288 saplings of six tree species native to the Northeastern United States. These species (deciduous broadleaf angiosperms, …

Microsite Requirements For Successful Regeneration In Lowland Northern White-Cedar (Thuja Occidentalis) Forests, Jeanette Allogio

Electronic Theses and Dissertations

Declines in stands of northern white-cedar (Thuja occidentalis L., hereafter cedar) have been observed as both shifts in species composition and reductions in cedar densities, particularly those stands in lowland sites (Curtis 1946, Boulfroy 2012). While several factors inhibiting cedar regeneration have been identified, a thorough understanding of the conditions that best promote regeneration is lacking. Our objectives for the first chapter were to characterize the site conditions associated with successful regeneration in lowland cedar stands and to describe how spatial patterns of various cedar size classes relate to site preference and to regeneration dynamics. These objectives were achieved …

Fostering Climate Change Resilience: A Socio-Ecological Forest Systems Approach, Alyssa R. Soucy

Electronic Theses and Dissertations

As climate change continues to impact socio-ecological systems, those that rely on natural resources are highly sensitive to climatic changes. Maine’s forest industry provides for the economic and social well-being of many residents and is especially vulnerable to climate change impacts. Changes in growing season length and timing, forest health threats imposed by insects and pathogens, extreme weather events, shifting forest composition, and changes in natural disturbance severity and frequency have already begun, and are projected to continue, to impact forest systems in the Northeastern U.S. While climate change presents a threat to forest systems, opportunities also arise due to …

Spruce Budworm Defoliation Dynamics And Its Influence On The Acadian Forest, Cen Chen

Electronic Theses and Dissertations

Spruce budworm (SBW; Choristoneura fumiferana (Clem.)) is the primary forest defoliator in North America. SBW defoliation has affected tens of millions ha of forests during its periodic outbreaks and caused severe growth reduction and mortality of spruce-fir (Picea-Abies) species. Evaluating these damaging effects of SBW defoliation requires understandings of the variation and dynamics of defoliation, as well as trees' variable responses to defoliation in consideration of various tree- stand-, and site-level factors. In this dissertation, we developed statistical models to 1) evaluate influences of SBW defoliation on spruce-fir stand dynamics of annual volume net growth, mortality, …

Ecological Consequences Of Personality In A Guild Of Terrestrial Small Mammals: From Trappability To Seed Dispersal, Allison M. Brehm

Electronic Theses and Dissertations

Individual animals exhibit consistent behavioral tendencies over time and across contexts that have been termed personalities. Personality encapsulates an individual’s unique way of behaving and responding to life’s challenges, and since individuals vary in both personality type and their ability to exhibit behavioural plasticity, there are important links between an individual’s personality and its response to a changing environment; resulting in the study of animal personalities becoming increasingly popular in recent years. Previous research suggests that personality traits measured through standardized behavioural tests predict trappability (i.e. ‘trap happiness’ versus ‘trap shyness’). This relationship has been explored only within single …

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

Drivers Of Tree Growth And Mortality In An Uneven-Aged, Mixed-Species Conifer Forest Of Northeastern United States, Erin Fien

Electronic Theses and Dissertations

Individual tree growth and mortality drive forest stand dynamics and are important, universal metrics of tree success. Studying the factors that affect growth and mortality is particularly challenging in mixed-species, uneven-aged systems due to their defining heterogeneity and strong temporal and spatial variability. However a better understanding of the factors driving growth and mortality in mixed-species, uneven-aged forest is crucial to managing and maintaining these valuable systems for the future.

The goal of this study was to determine the relative importance of individual tree attributes (e.g., species, size, neighborhood crowding, crown position) and environmental characteristics (e.g., soil moisture) in driving …

Nitrogen Cycling During A Period Of Environmental Change, Kaizad Patel

Electronic Theses and Dissertations

Natural and anthropogenic disturbances have altered the N cycle on the regional to global scale. Although numerous studies have examined the effects of chronic atmospheric N deposition on ecosystem processes, less is known about intra-annual variability of these processes, or how these responses might be altered under conditions of changing climate. The work described in this dissertation focuses on the effects of a changing chemical and physical climate, particularly terrestrial N processes (a) during Maine’s changing winters, and (b) in response to chronic elevated N additions.

Subnivean winter soil processes were examined at the Dwight B. DeMerritt Forest (DBDF) and …

Forest Disturbance Detection And Aboveground Biomass Modeling Using Moderate-Resolution, Time-Series Satellite Imagery, John B. Kilbride

Electronic Theses and Dissertations

Human-induced and natural disturbances are an important feature of forest ecosystems. Disturbances influence forest structure and composition and can impact crucial ecosystem services. However, deriving spatially explicit estimates of past forest disturbance across a large region can prove challenging. Researchers have recognized that remote sensing is an important tool for monitoring forest ecosystems and mapping land use and land cover change. One of the most important sources of remotely sensed imagery is the United States Geologic Survey’s Landsat program which has continuously acquired earth observations since 1972. This repository of imagery has the spatial, spectral, and temporal resolution necessary to …

Old-Growth Characteristics Of Northern White-Cedar Stands, Nathan Wesely

Electronic Theses and Dissertations

Northern white-cedar (Thuja occidentalis; hereafter white-cedar) communities have received relatively little research attention, and managers lack the tools used in the management of other commercial tree species. This includes the recognition of old-growth characteristics and the differentiation between old-growth and partially harvested stands, particularly in the context of Forest Stewardship Council (FSC-US) certification. Specifically, there is very little information about characteristics that define old-growth white-cedar stands despite the species’ abundance and wide distribution. Regional indices for late-successional or old-growth stands (Whitman and Hagan, 2007) do not include white-cedar. Forests dominated by white-cedar represent a type that currently lacks …

Individual Tree Measurements From Three-Dimensional Point Clouds, Elias Ayrey

Electronic Theses and Dissertations

This study develops and tests novel methodologies for measuring the attributes of individual trees from three-dimensional point clouds generated from an aerial platform. Recently, advancements in technology have allowed for the acquisition of very high resolution three-dimensional point clouds that can be used to map the forest in a virtual environment. These point clouds can be interpreted to produce valuable forest attributes across entire landscapes with minimal field labor, which can then aid forest managers in their planning and decision making.

Biometrics derived from point clouds are often generated on a plot level, with estimates spanning many meters (rather than …

Modeling Individual Tree And Snag Dynamics In The Mixed-Species Acadian Forest, Matthew B. Russell

Electronic Theses and Dissertations

Forest growth modeling has a long tradition of development and application in even‐aged stands targeting single-species plantations. Modeling efforts in mixed-species stands that contain uneven‐aged stand structures are much more recent. Serving as a transitional zone between the boreal and eastern broadleaf deciduous forest types, the Acadian Forest found throughout Maine and the Canadian Maritime Provinces is host to a wide variety of tree species that form complex stand structures. This study validated existing and developed component equations that comprise a widely-used individual tree growth and yield model in the northeastern US and Canadian Maritime provinces. An assessment of deadwood …

U.S. Forest Service Northern Conifer Experimental Forests: Historical Review And Examples Of Silvicultural Research Applications, Kate Berven

Electronic Theses and Dissertations

This study investigates U.S. Forest Service silvicultural research in the northern mixed-conifer forest of the Northeast. Chapter 1 is an overview of three closed experimental forests and is a cautionary tale regarding lost research opportunities. The Paul Smith, Finch-Pryun, and Gale River Experimental Forests (EFs) were established in the early to mid 1900s. Changing societal needs and research priorities led to redirected staffing and funding; all three were disestablished. Initial investments were lost and outcomes of the experiments not fully realized. This chapter highlights the importance of retaining and properly storing records. The Penobscot EF is an exemplary illustration of …

Forest Succession And Amphibian Migrations: Implications For Landscape Connectivity, Viorel Dan Popescu

Electronic Theses and Dissertations

Conservation of forest-dependent amphibians is dependent on finding a balance between timber management and species’ habitat requirements. Accurate predictions of the response of amphibian communities to disturbance rely on a good understanding of the scales at which ecological processes affect distribution and abundance through space and time. I investigated the response of 14 species to four different forestry treatments (partial harvest, clearcut with coarse woody debris [CWD] removed, clearcut with CWD retained, and uncut control) over a six-year period, using 2.1-ha experimental treatments. Forest amphibians showed a strong negative response to complete canopy removal at a broad spatial scale, but …

Patterns Of Regeneration Of Eastern White Pine (Pinus Strobus L.) As Influenced By Large Isolated Reserve Trees And Precommercial Thinning, Kate E. Zellers

Electronic Theses and Dissertations

The spruce budworm epidemic of the 1970s and 1980s led to the salvage harvesting of spruce-fir stands, serving as a release for scattered immature eastern white pine (Pinus strobus L.) trees. These pines are now growing as large isolated reserve trees above a mixed conifer regeneration stratum. The objectives in this study were to determine any effect of varying levels of basal area (m² ha^-1) of large pine reserve trees may have on (1) the densities (stems ha^-1) of both eastern white pine and non-pine species in the developing regeneration stratum, and (2) the …

Monitoring Vegetation Change By Using Remote Sensing: An Examination Of Visitor-Induced Impact At Cadillac Mountain, Acadia National Park, Min Kook Kim

Electronic Theses and Dissertations

Cadillac Mountain, the highest peak along the eastern seaboard in the United States, is a major visitor destination at Acadia National Park. Managing vegetation impact on the summit of Cadillac Mountain is extremely challenging given the number of users and dispersed nature of visitor use at this fragile environmental setting. Since 2000, more intensive management strategies based on placing physical barriers to protect threatened vegetation and leave no trace signs have been employed to reduce vegetation impact and enhance vegetation recovery in the vicinity of the summit loop trail. A number of different change detection techniques and high resolution remote …

Influence Of Silvicultural Treatment, Site Characteristics, And Land Use History On Native And Nonnative Forest Understory Plant Composition On The Penobscot Experimental Forest In Maine, Elizabeth Bryce

Electronic Theses and Dissertations

This study investigates forest understory plant diversity and composition in managed and unmanaged stands within the context of a long-term silvicultural experiment in the Acadian Forest of Maine. I examined the effects of silvicultural intensity and past land use on understory plant species diversity and composition. Silvicultural treatments include three variants of the selection system, three variants of the shelterwood system, modified and fixed diameter-limit cutting, and an unregulated harvest. Two types of unmanaged stands were studied: a continuously forested natural area and secondary forest stands on old fields. Chapter 1 presents analysis of understory plant diversity and composition in …

The Chemistry Of Acidic Soils In Humid, Temperate Forested Watersheds With Emphasis On Phosphorus, Aluminum And Iron, Micheal Sanclements

Electronic Theses and Dissertations

Acidification of soils can result from natural processes (i.e. pedogenesis) and from atmospherically derived sulfur (S) and nitrogen (N) which originate from anthropogenic emissions. Research on the effects of acidification has typically focused on base cations, N and aluminum (Al). The Bear Brook Watershed in Maine (BBWM) (a long-term, whole-watershed acidification experiment) demonstrated increased episodic stream export of Al, iron (Fe), and phosphorus (P) in the treated watershed, suggesting that acidification can also affect P. This research evaluates (a) the physical and chemical distribution of P, (b) mechanisms controlling soil P accumulation, mobilization, and availability in humid, temperate forested ecosystems, …

Study Of Basic Wood Decay Mechanisms And Their Biotechnological Applications, Yuhui Qian

Electronic Theses and Dissertations

The overall objective of this thesis was to gain further understanding of the non-enzymatic mechanisms involved in brown-rot wood decay, especially the role of pH, oxalic acid, and low molecular catecholate compounds on the dissolution and reduction of iron, and the formation of reactive oxygen species. Another focus of this study will be the potential application of a biomimetic free radical generating system inspired from fungi wood decay process, especially the non-enzymatic mechanism. The possible pathways of iron uptake and iron redox cycling in non-enzymatic brown-rot decay were investigated in this study. UV-Vis spectroscopy and HPLC were employed to study …

The Effects Of Chronically Elevated N And S Deposition On The Nutrition And Physiology Of Sugar Maple At The Bear Brook Watershed In Maine, Suzanne Bethers

Electronic Theses and Dissertations

The Bear Brook Watershed in Maine is a paired watershed system; one watershed has been acidified bimonthly with granular ammonium sulfate ((NH₄)₂SO₄) since 1989. The adjacent watershed is used as a reference. This acid deposition treatment presents unique opportunities to look at the long term affects of acidification on vegetation. Acidic deposition continues to be a concern for the health of sugar maple (Acer saccharum Marsh.) in northern hardwood forests. Many studies show a connection between base cation depletion induced by acid deposition and sugar maple decline. In this text we …

Relative Fitness And Behavioral Compensation Of Amphibians In A Managed Forest, Sean Michael Blomquist

Electronic Theses and Dissertations

Habitat loss and degradation are two of the most important factors leading to the imperilment of species worldwide including amphibians, but mechanisms underlying these changes are poorly understood. To understand the fitness potential of harvested forests, I conducted studies of a forest specialist, Rana sylvatica (Wood Frogs) and compared these results with those from identical studies with an open canopy specialist, R. pipiens (Northern Leopard Frogs) in response to an unharvested control and three forest harvesting treatments: clearcutting (with removal of all merchantable timber > 10 cm diameter), clearcutting with coarse woody debris retention, and partial harvesting with removal of < 25% canopy cover. First, I used radio-telemetry data collected on 72 adult R. …