Author ORCID Identifier
https://orcid.org/0009-0008-0990-8767
Date of Award
6-2025
Document Type
Thesis (Undergraduate)
Department or Program
Biological Sciences
First Advisor
Shersingh Joseph Tumber-Dávila
Abstract
Anthropogenic land use change and development has caused widespread global forest fragmentation, resulting in a greater proportion of forests at or near a forest edge. Temperate forests are the most fragmented forest biome, and forests in the Northeastern U.S. are particularly fragmented due to a history of intense land use and development pressure. Nearly a quarter of these forests are now within 30 meters of a forest edge. These edge ecosystems have distinct abiotic and biotic gradients that differentiate them from forest interiors, including increased light, temperature, and exposure to wind and other disturbances, as well as decreases in humidity and soil moisture. Unlike in tropical forests, edge conditions in temperate regions have led to increased aboveground growth and biomass. Effects of edges on belowground biomass are much less understood, and current estimates of net primary productivity and carbon storage at temperate edges are largely based on aboveground observations. However, belowground systems can greatly affect ecosystem-wide biogeochemical cycling of nutrients and carbon. In order to gain a more comprehensive understanding of biomass shifts along forest edges, soil, root, and microbial samples were collected in the summer of 2024 at a recent forest clearcut site at Harvard Forest in Petersham, MA. I investigated shifts in root biomass pools across an anthropogenic forest edge, including live fine tree roots, root necromass, and herbaceous and shrub roots, as well as shifts in microbial biomass and functional group composition using PLFA analysis. I observed an increase in live fine root biomass below a soil depth of 20 cm at the forest edge, with increases specifically associated with Quercus rubra (red oak). These root biomass differences may be related to the observed drier soils that could cause root proliferation at depths with relatively more water availability. There were also more Gram-negative bacteria-associated PLFAs at the edge below a soil depth 20 cm, although no other differences in microbial biomass or functional group composition were observed. Contrary to my hypotheses, root and microbial biomass were not significantly different between the forest interior and forest clearing. These results suggest that there are species-specific shifts in fine tree root biomass along temperate forest edges, highlighting the plasticity of root systems to abiotic conditions and indicating increased potential for carbon sequestration and storage along temperate edges, particularly in oak-dominated temperate forests. Belowground biomass pools must be incorporated into future studies in order to get a comprehensive understanding of forest response to edge conditions, especially as climate change and other disturbances exacerbate conditions along the edge.
Recommended Citation
Roelofs, Lara Holbrook, "Belowground Biomass Shifts Along a Temperate Forest Edge" (2025). Dartmouth College Undergraduate Theses. 275.
https://digitalcommons.dartmouth.edu/senior_theses/275
