Our Research

To get a list of our active grants click here: Active Grants .

Terrestrial Biogeochemistry: A central theme of my group’s research is 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) stresses.   These responses are tracked within litter and below ground organic matter reservoirs as well as aquatic fractions and studied to determine the specific effects upon soil and aquatic organic matter dynamics and microbial responses.  Our work involves collaborations with Native American tribal nations, Midwest regional farmers, national laboratories and numerous academic institutions. 

Our recent projects include:

• The Impact of invasive earthworm activity on forest dynamics (Filley et al., 2008a-see manuscripts page) Two of our projects, both funded by NSF, investigate the response of forest ecosystems to native and invasive earthworms.
  • In a collaboration (start date August 2008) with the Smithsonian Environmental Research Center and The Johns Hopkins University we investigate the microbial, chemical, and structural responses of forest litter and soil an eastern tulip poplar forest to variation in earthworm activity. Additionally, long term litter manipulation plots are used to gauge the ability of earthworms to partition litter among aggregated and non aggregated soil pools.
  • In a collaboration with Red Lake Nation of Chippewa and Bemidji State University (Start Date Jan 2006) we are using culturally relevant science questions surrounding the impacts of European invasive earthworms on the forest structure in the northern hardwood forest of the Red Lake Nation to introduce and excite Ojibwa tribal college students about the earth sciences.
  (click here to see collaborations with Red Lake MN Tribal College)

• The Impact of thorn woodland encroachment into grasslands in a semitropical setting on soil organic matter stabilization (Boutton et al., 2007; Filley et al 2008b-see manuscripts page). In a collaboration with Texas A&M University and Argonne National Laboratory we are investigating the response of soil to woodland encroachment in a semitropical savanna in southern Texas. Our focus is to relate plant chemistry, soil structure, and microbial activity, to the mechanisms of soil organic matter stabilization and destabilization.

• The Impact of elevated CO2-induced increases in forest productivity on soil structure and SOM stabilization (see link) C and N biogeochemical cycling in soils (soil formation, C-stabilization, soil responses to perturbations))

• Biogeochemical cycling of terrestrial organic matter controlled by land use and hydrology (see link) Mechanistic controls of mineralogy, source chemistry and hydrologic pulses on terrestrial Biogeochemistry
• The relationship between river discharge and terrestrial organic matter sources <(Dalzell 2005; Dalzell 2007; Bianchi 2004; Bianchi 2007)

• The relationship between source chemistry and the stabilization of litter and soil (Filley et al., 2006; Sollins et al., 2006; Nierop and Filley 2007)

Terrestrial Environmental Chemistry: Additionally, we use the above biogeochemical perspective to investigate how emerging pollutants respond in the natural environment.  Our projects have focused on brominated flame retardants (Ahn et al., 2005; Ahn et al., 2006) and, most recently, the microbial response to manufactured nanocarbon (Schreiner et al., in review) and black carbon (see nanocarbon link below).  We combine microcosm and laboratory experiments to observe how microbes and minerals change the chemical nature form of these pollutants and, potentially, alter the rate at which they cycle in natural settings and make their way into living and nonliving reservoirs. (Environmental Fate of Nanocarbon Materials)

Biofuels research: Brown rot wood-degrading fungi accomplish naturally what bioconversion technologies currently do not: complete removal (>99%) of plant polysaccharides from lignocellulosic tissues without removing or damaging lignin. The lignin modifications (demethylation, side chain oxidation, hydroxylation) seen in residues from brown rot fungi may be an important link to understanding fungal mechanisms of sugar release (saccharification). While the predominant theory has been that modifications increase pore size and thus allow enzymes to penetrate the plant cell wall, most brown rot fungi cannot degrade crystalline cellulosics if lignin is absent. This observation remains unresolved and characterizing this dynamic has significant implications for commercial biorefining.

We hypothesize that lignin modifications precede enzyme-mediated hydrolysis and that modified lignin actively facilitates saccharification during brown rot. Successfully utilizing an approach similar to that of brown rot fungi offers an alternative to engineering plants with altered lignin content or to delignifying feedstocks prior to processing. We have strong commercial participation in this project. With the goal being to characterize then utilize the brown rot approach to enhance C5 and C6 sugar release from biomass, our specific aims are

1. to determine the discrete timing of lignin modifications
2. to correlate these alterations with biocatalyst efficiency and ingress into plant cell walls
3. to reproduce modifications prior to saccharification for efficient bioprocessing.

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