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Earthworm invasions as drivers of soil carbon sequestration in north temperate forests

Project Abstract: 
<p>This research will answer unresolved questions regarding changes in forest carbon (C) sequestration in response to exotic earthworm invasions involving multiple earthworm species. The impacts of earthworm invasions remain undescribed on sandy forest soils, and to date no single study has examined changes in all major components of a forest soil C budget (particulate, dissolved, and gaseous) associated with earthworm activity. Further, no study has examined how interactions among earthworm species will affect net C storage in north US temperate forest soils. This dissertation research will:</p><p>1.&nbsp;Characterize spatial and temporal variability of exotic earthworm communities in a north temperate forest. The species composition and density of earthworm communities in north temperate forests growing on sandy soils has not been described in the literature, nor have changes in these communities as a function of forest succession been considered. This work is part of a collaborative effort at UMBS where the Forest Accelerated Succession Experiment is hastening mortality of early successional dominant tree species and investigating changes in ecosystem processes accompanying successional trajectories and C storage.&nbsp;</p><p>2. Establish fundamental baseline data (in the form of soil C budgets) to compare earthworm community impacts on soil C content. Using a nearly completed mesocosm experiment involving three earthworm species belonging to different functional groups, relationships among earthworm community composition changes in soil carbon, cumulative CO2 losses, and dissolved organic C losses will be resolved to explain how shifts in earthworm communities affect soil C budgets.</p><p>3. Link variations in the magnitude and distribution of soil C content to the functional diversity of earthworm communities, soil texture, and interactions between these two factors. Isotopically labeled (13C and 15N) litter additions to mesocosms in which soil texture and earthworm community composition are manipulated in a two-way comparison will be used to track litter C and N redistribution by earthworm functional groups. This will allow calculation of the net impacts of earthworm communities on soil C storage and redistribution.</p>
Years Active: 
2011 to 2014
Methods include field surveys of earthworm species abundance and community composition across the FASET and AmeriFlux site, laboratory experiments conducted in the UMBS soil biotron to examine the impacts of earthworm communities on soil carbon balance, isotopic analysis of earthworms, soil, and litter, to analyze spatial and temporal patterns in earthworm diet.
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