Forest Biology Commons^™

Visualizing 25 Years Of Change In The Glades Oak Savanna, Zoe Fieberg

Summer Research Showcase

Oak savannas represent one of the most threatened ecosystems in Minnesota due to changing land use management, particularly absence of fire (Davis, 2001). Frequent burns kill fire-sensitive mesophytic tree species, reducing the dominance of woody understory and allowing for restoration of the oak savanna environment. The GLADES (Grid for Landscape Analysis and Demographic Study) site was established in 1988 in East Bethel, Minnesota to study the effect of frequent burning on oak savanna restoration. Through the use of standardized methods of photography, we compared canopy differences across GLADES between 2001 and 2026. Preliminary observations revealed increased canopy density and reduced …

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 …

Considerations And Challenges For Oak-Pine Woodland Restoration In The Southern Appalachians, Armin Weise

All Dissertations

Appalachian forests in the southeastern United States are composed of fire-adapted communities. These have historically been burned by native Americans and by lightning-ignited fires, causing widespread ignitions across the landscape for millennia that have shaped the forest and the species within it. Many of the more xeric oak-pine forest systems in the region were more akin to woodlands with open midstories, understocked canopies, and a diverse understory layer of herbaceous species and shrubs. With the decline of Native Americans due to disease and forced removal, fire across the landscape declined, a trend compounded by fire-suppression policies put forth by the …

Exploring The Relationship Between Tree Dbh And Lichen Cover On Coast Redwood, Grace M. Personeus, Sierra Gittleman, Alisa A. Zarattini

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

We investigated the relationship between Diameter at Breast Height (DBH) and lichen cover on coast redwood (Sequoia sempervirens) to see if larger trees had higher percentages of cover. We measured cover using 10 cover classes on the southeastern and southwestern sides of trees in a secondary growth forest. We found a significant relationship between DBH and cover, yet no significant difference between the two sides measured. We suggest that further research with a larger sample size and more varied age classes will provide further insight into the relationship.

Exploring The Effects Of Pest-Induced Hemlock Mortality On Growth In Neighboring Trees, Sidney L. Booher

McNair Culminating Research Projects

Trees provide many important products and services to humans. In particular, tree growth is critical to carbon storage, air and water quality, and helps determine demographic processes like population growth and reproductive success. Importantly, tree growth is sensitive to both abiotic (environmental) and biotic factors and is vulnerable to ecological disturbances. Understanding how tree populations respond to disturbances, like invasive pests, is therefore crucial to formulating timely and effective forest management practices.

Here, I used tree ring analysis to investigate how competition for water between neighboring trees changes following the decline of Eastern and Carolina Hemlock(ECH) trees due to the …

Forest Overstory Mortality & Recruitment Patterns Eight Years Following Wildfire In The Southern Appalachians, Ruth Cumberland

All Theses

In this study, we investigated patterns of forest overstory mortality and recruitment eight years after wildfire in a large wildfire site the Southern Appalachians, a topic that has not been thoroughly investigated to date. With evidence that pre-fire drought promotes post-fire mortality through impaired physiological function and increased fuel consumption, unknown patterns following wildfire are important to study under shifting climate and land-use conditions. In Chapter 1, three areas of interest were investigated: (a) functional group mortality response to wildfire effects, (b) temporal differences in early (1-3 years) and late (5-8 years) periods of delayed forest overstory mortality patterns following …

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 …

Leaf Droppage Delayed In Sugar Maple Trees On An Urban To Rural Gradient, Isabella S. Bastien, Isabella Bastien

The Cardinal Edge

This study investigates the timing of leaf abscission in Sugar Maple (Acer saccharum) trees along an urban-to-rural gradient in Louisville, Kentucky, to determine how proximity to urban environments influences leaf drop. We hypothesized that urban trees would retain their leaves longer than suburban or rural trees due to environmental stressors and tested this using weekly leaf collection and canopy cover measurements from three locations—urban, suburban, and rural. Results showed that urban trees exhibited delayed leaf drop and slower canopy opening compared to suburban and rural trees. These findings suggest that urban stressors significantly alter tree phenology, which may signal underlying …

Solvent Extracts Of Pulvigera Papillosa (Orthotrichaceae) Show No Antimicrobial Properties In Disk Diffusion Tests, Ryan A. Solorzano, Justin Paulin, Grayson Prater, Michael Lanier

Humboldt Journal of Microbiology

Abstract As antibiotic-resistant bacteria become more prevalent, the search for novel forms of antibiotics in the natural world has become an increasingly worthwhile endeavor. Many mosses have been found to contain antimicrobial properties, including those in the family Orthotrichaceae. Pulvigera papillosa, an Orthotrichaceous moss native to California, has thus far not been investigated to determine whether it contains antimicrobial properties. Extraction techniques using polar and nonpolar solvents have proven to be effective in extracting the secondary metabolites that allow mosses to defend themselves against a hostile microbial world. This study takes a preliminary look into the antimicrobial properties of P. …

Stand Strucuture Of Planted Stands In Storm-Water Retention Basins, Jason Lanza

Electronic Theses and Dissertations

Trees assist in stormwater retention basin functionality as efficient sources of water removal, and determining stand structure and leaf area of forests can be a measure of their effectiveness. The structure of forest stands on these basins managed for runoff mitigation has received little attention. We investigated the structure and species composition/diversity (tree and herbaceous) of planted, managed stands and naturally regenerated stands on stormwater retention basins managed by Harris County Flood Control District in Harris County, Texas. We determined stand structure variables (trees per hectare, basal area per hectare, quadratic mean diameter, relative density, average tree height, and percent …

Limited Soil Water Recharge In Summer Affects Seasonal Isotopic Signatures Of Tree Xylem Water, Marius G. Floriancic, Gregory R. Goldsmith, Harsh Beria, Scott T. Allen, James W. Kirchner

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Recent studies have reported that xylem waters in forest trees during the summer growing season are often isotopically similar to winter, rather than summer, precipitation. Several hypotheses have been proposed to explain this observation, which can be viewed as a form of ecohydrological separation, but empirical tests spanning space and time remain limited. We hypothesise that variations in the seasonal origin of precipitation found in tree xylem waters can be explained by seasonal differences in soil water recharge. We test this hypothesis by evaluating to what extent climatic aridity can explain seasonal signals in extensive surveys of the isotope ratios …

Integrating Belowground Recovery Into Tropical Forest Restoration Design And Monitoring, Lauren Toro, Leland K. Werden, Shalom D. Addo-Danso, Kelly M. Andersen, Sarah Batterman, Matilde M. Bragadini, Pooja Choksi, Rebecca J. Cole, Liza S. Comita, Daniela Cusack, Daisy H. Dent, Lee H. Dietterich, Joshua B. Fisher, Katrin Fleischer, Lucia Fuchslueger, Nohemi Huanca-Nunez, Janey R. Lienau, Lindsay A. Mcculloch, Ember M. Morrissey, Jennifer S. Powers, Mareli Sánchez-Juliá, Oscar Valverde-Barrantes, Anita Weissflog, Michelle Y. Wong

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

There is growing recognition that tropical forest restoration is key for sequestering carbon and enhancing ecosystem resilience. Soils, roots, and soil biota are central to ecosystem function and services, but belowground recovery is largely overlooked in restoration monitoring frameworks. Here, we outline current understanding of the links between above- and belowground recovery in tropical forests by examining how belowground properties before and after intervention influence recovery; by evaluating whether aboveground recovery can serve as a proxy for belowground dynamics; and by proposing a blueprint for monitoring dynamic soil physical (bulk density, aggregate stability), chemical (organic matter or carbon, pH), and …

Catching A Fever: A Comparison Of Vachellia Xanthophloea Populations In The Limpopo And Luvuvhu River Floodplains Of The Makuleke Contractual Park, Kianie B. David

School of Natural Resources: Dissertations, Theses, and Student Research

This study investigates patterns of stand structure regeneration, growth characteristics, and coarse woody debris (CWD) patterns in Vachellia xanthophloea (fever tree) stands within the Makuleke Contractual Park (MCP), a semi-arid savanna system in northern Kruger National Park (KNP), South Africa. Fieldwork was conducted across two stand types: a monospecific fever tree stand in Rietbok Vlei and a mixed-species stand in the Western Nhlangaluwe Floodplain where fever tree is established with Faidherbia albida (ana tree). Data were collected from 20 total 1/4-acre (1,011 m²) circular plots between both stands in 2024 and 2025, including seedling root collar diameter (RCD), …

Monitoring Mangrove Dynamics And Evaluating Future Afforestation Potential In The Egyptian Red Sea, Rasha M. Abou Samra, Mansour Almazroui, Wenzhao Li, Hesham El-Askary

Mathematics, Physics, and Computer Science Faculty Articles and Research

Mangrove forests are vital for ecosystem services and coastal management but face stressors from anthropogenic activities and climate change. This study estimates the extent and afforestation potential of mangroves along the Egyptian Red Sea coast from 1984 to 2022 using NDVI derived from Landsat-5 and Sentinel-2 data in Google Earth Engine. Aboveground biomass (AGB), belowground biomass (BGB), carbon (C) stock, and CO₂ sequestration potential were evaluated using Sentinel-2 and elevation data. Future afforestation suitability (2020–2050) under SSP2-4.5 and SSP5-8.5 scenarios was assessed with the MaxEnt model. Mangrove area increased from 0.95 km² in 1984 to 1.46 km^{2 …}

Patterns Of Fire History And Vegetation Changes In The Last 5000 Years: A Paleoecological Study Of Iquitos, Annabel Zwarts

Theses and Dissertations

The vegetation of the Amazonian rainforest is hypothesized to have been shaped by pre-Columbian activities, such as burning and palm management to various extents. Management of palms is hypothesized to have caused some of the most useful species to become hyperdominant in Amazonia. This study investigated the extent to which human activities over the past 5000 years affected palm abundances in mature lowland rainforests near Iquitos, Peru. I used phytoliths and charcoal from soil cores to determine the history of local floras, and modern palm surveys to compare modern phytolith occurrence with modern vegetation. Because pre-Columbian activity clustered along the …

Life After Death: Investigating The Resistance And Recovery Of Fungal Communities To Foundation Tree Mortality, Jessie F. Marlenee

Biology ETDs

Tree mortality can have cascading effects on the composition and resilience of interacting fungal communities. Yet, little is known about the impact tree mortality, distinct from abiotic drivers (i.e., drought), has on these communities. This dissertation focuses on the resilience of fungal communities to experimental tree mortality in a piñon-juniper woodland. In chapter one, I found that piñon mortality reduced piñon fine root biomass and piñon mycorrhizal fungal diversity, whereas juniper mycorrhizal fungi were unaffected by juniper mortality. In chapter two, I revealed that piñon mortality altered the composition and spatial structure of mycorrhizal and saprotrophic fungi in the soil, …

Occurrence Of Spotted Wing Drosophila (Drosophila Suzukii) In Wild Berries In Forested Areas Of Marquette And Keweenaw Counties, Upper Peninsula Of Michigan, Alexis M. Shatrau, Erika I. Hersch-Green

The Great Lakes Entomologist

Spotted-wing Drosophila (SWD, Drosophila suzukii Matsumura, Diptera: Drosophilidae) is an invasive fly that targets unripe soft-fruits causing premature ripening, dehiscence, and rotting. While the presence of SWD in agricultural systems is well-documented, much less is known about the host range of SWD in wild areas, especially in more northern latitudes where colder temperatures and short summers are thought to restrict their life-cycles and limit population growth. In 2019 and 2020, we collected wild berries from two counties in the Upper Peninsula of Michigan, with long, cold winters, to determine the prevalence, host range, and seasonal/temporal variation of SWD. We found …

Woody Plant Reinvasion Shortens The Lifespan Of Grassland Restoration Treatments, Dillon T. Fogarty, Michele Beadle, Craig R. Allen, Christine Bielski, Dirac Twidwell

Biology Student Work

An important question in restoration ecology is whether restored ecological regimes are more vulnerable to transitions back to a degraded state. In woody-invaded grasslands, high-intensity fire can collapse woody plant communities and induce a shift back to a grass-dominated regime. Yet, legacies from woody-dominated regimes often persist and it remains unclear whether restored regimes are at heightened vulnerability to reinvasion. In this study, we utilize a 17-year history of fire-based restoration in Nebraska's Loess Canyons Experimental Landscape to determine whether restored grassland regimes experience faster rates of Juniperus virginiana (eastern redcedar) reinvasion compared to the initial invasion process in adjacent …

Assessing The Potential For Bigleaf Maple Syrup Production In Humboldt County, Ca, David A. Reinhart, Juan A. Ramos-Cool, Liam H. Richardson

Undergraduate Scholarship

The bigleaf maple (Acer macrophyllum, Pursh) is the largest maple of the Pacific Northwest. While it has generally been treated as a nuisance in timber harvesting operations, a small amount of research has been conducted on its sugaring ability in Oregon, Washington, and British Columbia. This research has yet to reach further south in the species' range. This study aims to help a California landowner understand which maple trees on his property produce the most maple sap, to gauge what environmental factors contribute to maple sap production, and to find greater implications for the production of maple sap …

Scaling Individual Tree Transpiration With Thermal Cameras Reveals Interspecies Differences To Drought Vulnerability, Mostafa Javadian, Donald M. Aubrecht, Joshua B. Fisher, Russell L. Scott, Sean P. Burns, Jen L. Diehl, J. William Munger, Andrew D. Richardson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Understanding tree transpiration variability is vital for assessing ecosystem water-use efficiency and forest health amid climate change, yet most landscape-level measurements do not differentiate individual trees. Using canopy temperature data from thermal cameras, we estimated the transpiration rates of individual trees at Harvard Forest and Niwot Ridge. PT-JPL model was used to derive latent heat flux from thermal images at the canopy-level, showing strong agreement with tower measurements (R2 = 0.70–0.96 at Niwot, 0.59–0.78 at Harvard at half-hourly to monthly scales) and daily RMSE of 33.5 W/m2 (Niwot) and 52.8 W/m2 (Harvard). Tree-level analysis revealed species-specific responses to …

Latticed Stinkhorn, Emilee G. Seigworth

PANDION: The Osprey Journal of Research and Ideas

Artist Statement

Latticed Stinkhorn is a watercolor piece originally created for the special gallery of the 2023 Scientific Illustration course at the University of North Florida. It was inspired by my enduring fascination with the world of fungi, particularly specimens of the family Phallaceae. This watercolor piece offers a simple perspective of Clathrus ruber, a species commonly referred to as Latticed Stinkhorn. Like many members of the family, the reproductive fruiting body first surfaces encased in a cream-colored soft shell with a texture comparable to a leathery reptile egg. As the body ages, the initial shell disintegrates to reveal a …

Chinese Tallow Long-Term Impact On Stand Dynamics In A Bottomland Hardwood Forest Following Vegetation Management, Nicklaus R. Langlois

Electronic Theses and Dissertations

Chinese tallow (Triadica sebifera (L.) Small) is an invasive tree known to have negative impacts on bottomland hardwood forests. Chinese tallow is proficient in reproducing and surviving in bottomland hardwood forests because it is more flood and shade tolerant than most native trees. The long-term effectiveness of Chinese tallow control is an important topic to research as only a few long-term studies of Chinese tallow control have been conducted. A 10-year re-measurement of 22 paired plots installed in 2012 on the Pineywoods Mitigation Bank near Diboll, Texas following herbicide treatments examined Chinese tallow and native tree stand structure. Each …

I’M A Forest, Not A Saltmarsh, Captain: Carbon And Sap Flow Dynamics In Coastal Forested Wetlands Of The Southeastern United States, Chris Shipway

All Theses

Coastal forested wetlands are identified as some of the highest-priority ecosystems for climate change mitigation. Here, we present two studies conducted in these unique ecosystems.

The first assessed changes in aboveground vegetative C stocks along the estuarine-riverine gradients of the Winyah Bay in South Carolina and the Savannah River in Georgia, using a space-for-time substitution to increase understanding of the impacts to upper estuarine forested wetlands from relative sea level rise. Standing C stocks on the Savannah River averaged 183.6 Mg C ha^-1, while sites on the Winyah system averaged 162.3 Mg C ha^-1. The largest …

New York City’S Rising Sea Level And Coastal Erosion: Approaches To Resiliency, Ryder D. Isidro

Student Theses 2015-Present

No abstract provided.

Vascular Epiphyte Population Dynamics Within Human-Modified Landscapes Of Guadalupe, Cerro Punta, Chiriquí, Panamá, Lucine Tashjian

Independent Study Project (ISP) Collection

Epiphytes are plants that grow on other plants non-parasitically, and globally, epiphytes compose a very large and diverse group. They are especially abundant and species-rich in the tropics- particularly, in tropical montane forest ecosystems. Human population growth in the tropics, however, has resulted in significant declines in forest cover with land being converted largely for agricultural purposes. Studies on epiphytes have traditionally been undertaken in pristine, undisturbed forest ecosystems, yet terrestrial land conversion has increased the need to understand the value of human-modified ecosystems for epiphytic populations and biodiversity conservation. This study sought to understand the relationship between human modification …

Automated Tree Mortality Detection Using Ubiquitously Available Public Data, Michael T. Huggins

Master's Theses

Understanding the dynamic interplay between fire severity, topography, and tree mortality, is crucial for predicting future forest dynamics and enhancing resilience against climate change-induced wildfire regimes. This thesis develops a multi-sensor approach for automated estimation of tree mortality, then applies it to examine trends in tree mortality over a six-year period across a fire affected study site in the Trinity River basin in Northern California. The Random Forest model uses publicly available USGS 3D Elevation Program Lidar (3DEP) and NAIP imagery as inputs and is likely to be easily adaptable to other landscapes. The model had a Receiver Operating Characteristic …

Toward A Coordinated Understanding Of Hydro-Biogeochemical Root Functions In Tropical Forests For Application In Vegetation Models, Daniela F. Cusack, Bradley Christoffersen, Chris M. Smith-Martin, Kelly M. Andersen, Amanda L. Cordeiro, Katrin Fleischer, S. Joseph Wright, Nathaly R. Guerrero-Ramírez, Laynara F. Lugli, Lindsay A. Mcculloch, Mareli Sanchez-Julia, Sarah A. Batterman, Caroline Dallstream, Claire Fortunel, Laura Toro, Lucia Fuchslueger, Michelle Y. Wong, Daniela Yaffar, Joshua B. Fisher, Marie Arnaud, Lee H. Dietterich, Shalom D. Addo-Danso, Oscar J. Valverde-Barrantes, Monique Weemstra, Jing Cheng Ng, Richard J. Norby

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Tropical forest root characteristics and resource acquisition strategies are underrepresented in vegetation and global models, hampering the prediction of forest–climate feedbacks for these carbon-rich ecosystems. Lowland tropical forests often have globally unique combinations of high taxonomic and functional biodiversity, rainfall seasonality, and strongly weathered infertile soils, giving rise to distinct patterns in root traits and functions compared with higher latitude ecosystems. We provide a roadmap for integrating recent advances in our understanding of tropical forest belowground function into vegetation models, focusing on water and nutrient acquisition. We offer comparisons of recent advances in empirical and model understanding of root characteristics …

Environmental Biology Masters Capstone, Antonio Gonzalez-Pita

Regis University Student Publications (comprehensive collection)

Human wildlife interactions (HWI) pose a complex challenge for wildlife managers. Human encroachment into wildlife habitat and the growing number of outdoor recreationists are increasing the frequency of contact and conflict, especially in regions such as the Front Range of Colorado. Geographic information systems (GIS), which use a combination of remote sensing and environmental survey data, allow for predictive spatial analyses of where human wildlife interactions are likely to occur. I used publicly reported observations of moose to create spatial predictive maps in a species distribution model framework. Slope and elevation were shown to be the strongest predictors of HWI, …

Biology And Ecology Of Neonectria Magnoliae And Neonectria Punicea, Two Understudied Neonectria Species In West Virginia, Hannah Marie Petronek

Graduate Theses, Dissertations, and Problem Reports (ETD)

The family Nectriaceae includes numerous phytopathogenic fungi that cause canker diseases on both angiosperm and conifer hosts worldwide. Numerous Neonectria spp. cause cankers on hardwoods and conifers in North America, but their roles in contributing to tree decline and mortality outside of beech bark disease are largely understudied. One such pathogen, Neonectria magnoliae, causes perennial cankers on two native hosts in central Appalachia: Fraser magnolia (Magnolia fraseri) and tulip-poplar (Liriodendron tulipifera). We also recently confirmed N. magnoliae from non-native star magnolia (Magnolia stellata) in West Virginia. Both native hosts occur in the central …

Quantifying The Ecological Effects Of Salix Fragilis On Riparian Habitat In Kittitas County, Washington, Landon Shaffer

All Master's Theses

Invasive species threaten plant community structure and function globally. Riparian areas, the zone near streams where water influences vegetation, are especially sensitive to invasive species colonization, suffering large-scale shifts in community composition. Salix fragilis (crack willow) is a nonnative riparian species abundant in the lower elevation tributaries of central Washington. Some speculate whether this willow should be listed as invasive in Washington, despite a lack of regional supporting evidence. I studied riparian communities dominated by either S. fragilis or native species in the Kittitas Valley and measured biodiversity, quantified differences in solar attenuation, and compared leaf decomposition rates to learn …