Identifying Ecosystem Controls on Soil Biodiversity: A US/UK Project
Principal investigators:
Diana H. Wall, Colorado State University
H. W. Hunt, Colorado State University
A.N. Parsons, Colorado State University
T. R. Seastedt, University of Colorado
T. Powers, University of Nebraska
Graduate student:
Mark St. John, Colorado State University
student research
The relationship between soil biodiversity and ecosystem functioning is primarily based at the level of soil biotic functional groups. This project examines soil biodiversity at the species and genetic levels of resolution and brings together molecular biologists, systematists, and biogeochemists. In addition, collaboration with a similar program in the UK, promotes the exchange of information on biodiversity (plants and soil biota) of our grassland systems through emails, www pages, scientific visits and joint project meetings.
Two central questions govern our US research: A) How do plants influence belowground biodiversity? and B) What are the consequences of soil biodiversity to ecosystem processes? Our specific hypotheses addressing these questions concern the controls of soil biodiversity on ecosystem functioning, and take advantage of: 1) manipulative field and microcosm experiments, 2) a range of taxonomic methods applied to selected soil-inhabiting invertebrate groups, and 3) an existing model of soil food webs and carbon and nitrogen flux for a grassland.
The US field research is located at the Konza Long Term Ecological Research (LTER) site near Manhattan, KS. Manipulations to plots on an area of this tallgrass prairie have been carried out for the last 12 years, and provide the basis for our investigations. Soil samples are divided between the investigators for an intensive analysis of biotic (mites, nematodes, earthworms, protozoa, fungi, and plants; abiotic (soil physical and chemical characteristics) and ecosystem (e.g. decomposition, NPP) parameters.
The data resulting from the project are complex and will provide many opportunities for syntheses through quantitative analysis, synthesis and modeling. Biotic groups include fungi, protozoa, soil nematodes, entomopathogenic nematodes, mites, earthworms, and plants. There are also abundant data on abiotic factors, e.g., soil physical and chemical characterization. For example, results from just one group of soil fauna, nematodes, indicate the greatest species richness of any global terrestrial site, with only 1/3 of the samples examined. Challenges for this project are twofold: 1) analyzing the large data base on soil and plant taxa and relating it to the ecosystem parameters in a reasonable time frame, and 2) improving our assessment of the effects of biodiversity on ecosystem functioning. A graduate student interested in quantitative analysis and modeling can greatly advance our understanding and insight into biodiversity and ecosystem functioning.
For more information on this project go to: http://www.nrel.colostate.edu/soil/us_uk/index.html
Student Research:
Identifying Ecosystem Controls on Soil Biodiversity: A US/UK Project
Mark St. John
Our understanding of soil organisms and communities lags far behind what we know for aboveground terrestrial systems. For example we have no idea how surveys of biotic inventories aboveground, which are usually heavily biased to plants, might relate to belowground communities. Also, we have little information on how the diversity of soil communities might influence ecosystem processes such as decomposition.
Mark St. John is studying both the relationship between aboveground grass and belowground mite diversity and the influence of mite diversity on ecosystem resistance and resilience to perturbation in a tallgrass prairie. His studies are the first of there kind, addressing these question in a natural system, the Konza Priarie.
Mark hopes to use ecological modeling techniques to gain insight into how belowground communities in the tallgrass prairie influence decomposition. Such models may provide valuable predictions for the consequences of changes in community structure which might be brought about by disturbance both small (tilling) and large (global change) in scale.
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