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The below ground effects of invasive species
It has been previously found that invasive plants can gain a competitive advantage against other plants by altering belowground processes such as decomposition and nutrient cycling. We are conducting a region wide comparison of soil N availability, C availability, microbial biomass and enzyme activity in soils beneath invasive plants that are a problem in our region (e.g. garlic mustard, glossy buckthorn, cow vetch, multiflora rose) and the native plants that occur in the same soils to determine the extent to which important terrestrial ecosystem processes are affected by invasive plants, and to gain insight into what makes these plants effective invaders, so that we will ultimately have the knowledge required to eliminate these noxious invasive plants and restore native plant communities.
Enzymatic controls on N mineralization
Nitrogen mineralization is the conversion of organic N to mineral N. This process involves the decomposition of a variety of different organic N forms, including proteins, chitin and peptidoglycan, and DNA and RNA. The goal of this research is to determine how much these organic N forms contribute to N mineralization in different places and times, and why. For this project we will measure the activities of a variety of microbial enzymes responsible for degrading different organic N forms in soils from a variety of environments, all collected several times a year, and compare the enzyme activities to overall N mineralization rates. We will also perform a variety of basic soil chemical characterizations to try and determine the factors that control N mineralization.
Microbial control of litter decay
The goal of this research is to explore the role of the microbial community in the conversion of litter to humus, a critical process affecting rates and quantities of soil carbon sequestration. We will investigate the functional links between decomposer microorganisms, litter chemistry, and nitrogen (N) using experiments that manipulate carbon (C) and N availability over the course of litter decomposition. To accomplish this we will set up laboratory incubations of deciduous leaf litters of contrasting chemical composition and add pulses of isotopically labeled C and N at different stages of decomposition. This will enable us to quantify C and N effects on the breakdown of the different chemical constituents in litter as decomposition proceeds. To determine how patterns of microbial community behavior are linked to decomposition we will monitor the activities of a variety of microbial enzymes associated with decomposition throughout the experiment.
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The biogeochemical importance of extra-cellular enzymes on plant roots
Plant roots are known to produce extracellular enzymes that can mineralize organic nutrients, such as phosphatases, but little is known about the variety of different enzymes that roots can produce, and how important these root enzymes are in biogeochemical cycling. The goal of this research is to use fluorescent staining techniques to screen roots from a range of different plant species for a variety of different extra-cellular enzymes, to determine the activities of the enzymes we find, and compare their activities to enzymes produced by microorganisms in the same soil environment.
To view past research projects, please click here.
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