Terrestrial biogeochemistry projects
The Filley Lab addresses fundamental processes controlling the stabilization and destabilization of soil organic matter as well as its reactivity once mobilized to streams and rivers. Projects in my lab explore the response of terrestrial systems to landuse/landcover change (agriculture and rangeland activity), hydrologic pulses (storm events), climate change (increased atmospheric CO2) and invasive species (earthworm activity). We track these perturbations by monitoring chemical, isotopic and microbial changes within litter, soil, and aquatic domains. Some specific projects are listed below.
Collaborative Research: Linking the Chemical Structure of Black Carbon to its Biological Degradation and Transport Dynamics in a Northern Temperate Forest Soil.
The Impact of elevated CO2-induced increases in forest productivity on soil structure and soil organic matter stabilization/destabilization.
Fire is a major controller of carbon (C) cycling in terrestrial ecosystems, by converting plant biomass to atmospheric CO2 and by contributing incompletely combusted biomass or "black carbon" (BC) to soils. The primary goal of the project is to clarify the chemical and physical structure of black carbon (BC) materials and their wood precursors and to determine how BC structure relates to its dynamics in the environment. The experimental approach will produce the first direct, in situ measurements of BC degradation rates in a temperate forest soil, in this case, a sandy Spodosol, which is representative of large forested regions of eastern North America. Moreover, the team will quantify the importance and activities of the main faunal and microbial degraders of BC materials produced at 300 and 450ºC, along with its precursor-wood in soil. They will quantitatively describe the BC and wood stabilization mechanisms and chemical transformations in soil over time. Also, the research will measure the effects of BC and wood additions on native SOC turnover rates. (Funded by National Science Foundation-Ecosystems-G&G) Jeff Bird (PI), CUNY, Tim Filley (PI), Knute Nadelhoffer, Univ. of Michigan (PI). In the micrograph to the left, confocal microscopic analysis of mesquite biochar exposed to a brown rot basidiomycete fungus shows the fungal hyphae and crystal precipitates (bright green nodules), presumably CaOxalate. The experiments are designed to test the nature of fungal decomposition of soil amended biochar.
To date, most field-scale CO2 enrichment studies have been unable to detect significant changes in soil C against the relatively large, spatially heterogeneous pool of existing soil organic matter. At Oak Ridge National Lab Free Air CO2 Enrichment (FACE) experiment and Rhinelander, WI Aspen FACE we are studying the dynamics of biopolymers in soil physical fractions to investigate molecular level controls on carbon stabilization under elevated CO2. Funding in part from Soil Carbon Responses to Elevated Atmospheric CO2. (Funded by DOE)-Tim Filley with Julie D. Jastrow (PI) Argonne National Laboratory.
Woodland encroachment into grasslands and abandoned agricultural land - impact on soil carbon and nitrogen stabilization.
Impacts of invertebrate activity on terrestrial ecology: soil dynamics, litter decay, biopolymer dynamics
Woody plant encroachment into grasslands is a global phenomenon that has the potential to dramatically change soil carbon and nitrogen pools in these systems and affect feedbacks that control atmospheric CO2. With collaborators from Texas A&M University, Argonne National Laboratory, and University of Newcastle on Tyne, and University of Amsterdam we are investigating the impact of woodland encroachment and platations on peaty soils, dunes, and semitropical savanna. Our focus is to relate plant chemistry, soil structure, and microbial activity, to the mechanisms of soil organic matter stabilization and destabilization. Funding in part from Collaborative Research: Impacts of Vegetation Change on Stabilization and Microbial Accessibility of Soil Organic Matter: A Microbiological, Isotopic, and Molecular Study. (Funded by NSF)-Tim Filley (PI) with Tom Boutton , Texas A&M and Diane Stott, National Soil Erosion Lab.
A significant fraction of all lignocellulose passes through macro and micro invertebrate guts. The fate of plant biopolymers once they are consumed by invertebrates is poorly understood. Our lab studies the impacts of both native and exotic species on plant chemistry . For example, two of our projects, both funded by the National Science Foundation, investigate the response of forest ecosystems to native and invasive earthworms. In a collaboration with the Smithsonian Environmental Research Center (SERC) and The Johns Hopkins University we investigate how variations in earthworm activity influence the microbial, chemical, and structural responses of forest litter and soil within an eastern tulip poplar forest. Additionally, long term litter manipulation plots are used to gauge the ability of earthworms to partition litter among aggregated and non aggregated soil pools.
Given that only 0.6% of doctoral scientists and 0.4% of doctoral engineers are Native American we established the GEMSscholars Project: an NSF funded research partnership between Purdue University, Bemidji State University, and Ojibwa Native American undergraduate students at Red Lake Nation College and Leech Lake Tribal College to increase the number of Native American students pursuing geoscience degrees. Our research centers around the forests in Red Lake, Minnesota where our overarching research goal is to determine whether or not invasive earthworms are altering forest ecosystem dynamics. The projects are designed to ask culturally relevant science questions and are student driven with significant field, laboratory, and open discussion components.
Funding in part from:
1. Collaborative Research: Investigating the soil-earthworm-litter system controls on the stabilization of organic matter in Eastern deciduous forests (Funded by NSF). Tim Filley (PI) in collaboration with PIs Kathy Szlavecz, The Johns Hopkins University, and Melissa McCormick, Smithsonian Environmental Research Center.
2. Collaborative Project: Mentoring Native American students for success in post-secondary programs in the Geosciences. (Funded by NSF) Tim Filley with PI Suzanne Zurn-Birkhimer, and co-investigators George Parker, Ken Ridgway, Purdue University), and Tim Kroeger and Pat Welley, Bemidji State University.