USGS Soil Carbon Research @ Menlo Park
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| Dr. Mark Waldrop - Projects | ||
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What are the effects of permafrost degradation on the storage and flux of surface and soil water, soil carbon, trace gases, and on shifts in vegetation composition? | |
| Soil moisture exhibits large seasonal and interannual variation, and also varies greatly along the landscape according to both static factors (geologic substrate, permafrost status) and dynamic processes (precipitation and evapotranspiration; water use by plants). Lake levels have changed in recent decades, therefore water tables and soil moisture in hydrologically linked terrestrial ecosystems have changed spatially and temporally as well. The response of boreal ecosystems, including associated biogeochemical processes, to changes in the hydrologic regime will have potentially large feedbacks to wildlife habitat, human subsistence, climate regulation, and ecosystem structure and function. Plant community composition is intimately tied to the moisture regime and plays a pivotal role in C storage, greenhouse gas fluxes, wildlife habitat, and human subsistence. Soil moisture and vegetation composition are critical drivers of CH4 fluxes from soils, CO2 fluxes, C storage, albedo, and the fire return interval of Alaskan ecosystems. Transitioning systems, whether from permafrost thaw, wildfire, or other events, can lead to large losses of C to the atmosphere and changes in the associated ecosystem services. Understanding the way in which ecosystems, biogeochemical processes, and ecosystem services respond to changes in hydrology will require studying plant-soil-water interactions at multiple scales. | ||
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Are there patterns to microbial diversity at continental scales? | |
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I am testing productivity-diversity relationships in soil microbial communities across two
continental transects in an effort to link ecological theory to soil processes. Over the course of
human history, little has marked our impact on biotic resources more than the loss of biodiversity.
Reductions in plant diversity are known to affect soil processes, ecosystem resilience, ecosystem
services, and human society. Yet understand little about the extent of microbial diversity, its
natural variation at large scales, the impact of anthropogenic activities on microbial diversity,
or mechanistic linkages between microbial diversity and soil processes. Over the past 200 years
and increasingly over the last few decades, a scientific revolution in microbial ecology has
unveiled a strikingly diverse microbial community inhabiting soils. Nonetheless, we understand very
little about what controls the diversity of microorganisms in soils, and how the level of soil
microbial diversity might alter the manner in which terrestrial ecosystems function. A newly
funded USDA project will allow us to uncover how soil carbon resources may control soil microbial
diversity and determine whether reductions in the soil genetic stock will affect soil carbon
cycling processes.
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Black carbon decomposition by microbial communities | |
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Black carbon,resulting from the oxidation of wood and forest floor carbon following wildfire, is
thought to be largely biologically unavailable, but this has not been thoroughly examined.
Utilizing 13C isotope techniques, I am determining whether black carbon can be decomposed
by soil organisms, whether the extent of decomposition is affected by microbial species, and whether
the mechanism of action is via extracellular oxidative enzymes. |
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Permafrost microbial communities and decomposition following thaw | |
| Carbon (C) stored within permafrost in northern boreal forest soils may become available for microbial metabolism if soil temperatures continue to increase over the coming decades, resulting in a positive feedback to climate warming. Understanding the potential of permafrost carbon to be degraded requires a detailed understanding of the microbiology and biochemistry of permafrost soils. Utilizing novel techniques in molecular biology, fluorometry, and mass spectrometry, we propose to analyze the biological and chemical constraints on C cycling at the molecular level. Testing the potential genetic and chemical limitations on decomposition are cutting-edge approaches that are only made possible through recent technological advances. Our detailed genetic and chemical analyses will provide data with which to make future predictions of C cycling processes, particularly when combined with larger scale biophysical and hydrologic models. | ||
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How does a moisture gradient and climate manipulation affect the abundance of C and N cycling microbial functional groups and associated processes? | |
| Moisture is one of the most important variables controlling carbon storage in northern ecosystems. In collaboration with Merritt Turetsky at University of Guelph and Dave McGuire (UAF and USGS) at the Bonanza Creek Long-Term Ecological Research (LTER) station, we are examining how natural gradients in soil moisture and manipulated soil moisture and temperature affect the size and activities of decomposers, methanogens, and N cycling organisms, and how these can be used to predict changes in biogeochemical process rates | ||
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U.S. Department of the Interior |
U.S. Geological Survey
URL: http://carbon.wr.usgs.gov/Waldropprojects.html
Page Contact Information: Kristen Manies
Page Last Modified: Wednesday, 08-Oct-2008 19:16:31 EDT
