Project Title: Ecosystem Response to Climate Change in the Western United States: Linking Carbon and Water Cycling Through Isotopic Studies of Soils
Mendenhall Fellow: Corey Lawrence, (650) 329-4961, firstname.lastname@example.org
Duty Station: Menlo Park, CA
Education: Ph.D. (Earth Sciences), University of Colorado, 2009
Research Advisors: Jennifer Harden, (650) 329-4949, email@example.com; Mark Waldrop, (650) 329-5005, firstname.lastname@example.org; Katharine Maher (Stanford University), (650) 329-4978, email@example.com; Carol Kendall, (650) 329-4576, firstname.lastname@example.org; Jayne Belnap, (435) 719-2333, email@example.com
Project Description: Climate change in the Western United States will simultaneously affect the water, carbon, and nutrient cycles of ecosystems, with concomitant changes in biological resources and the ecosystem services on which society depends. Of particular importance in the region is the seasonality and amount of precipitation, which are expected to shift toward drought conditions in the Western United States over the next 50 years. As a result, a decline in water available for plant growth and nutrient cycling in soils will likely lead to dramatic shifts in ecosystems and ecosystem services involving water and carbon.
The interactions of water and soil carbon are played out over varying temporal scales. Over short timescales of days to years, the frequency and intensity of precipitation influence primary productivity, microbial controls of organic matter decomposition, and transport and stabilization of dissolved organic matter in soils. Over longer timescales of decades to millennia, the balance of moisture controls plant community composition, chemical weathering and soil geochemical development, and geomorphology. These long-term, water-driven, processes are likely to feedback to the short-term controls of soil carbon cycling and may be important factors controlling spatial patterns of soil carbon stabilization across the landscape. Superimposed on this hierarchy of processes controlling soil carbon are natural and anthropogenic disturbances.
To best understand the interactions of the short- and long-term controls of water and role of disturbances for soil carbon stability and storage at the landscape scale, a combination of geochemical and isotopic (14C) measurements and novel mathematical modeling tools are required to explore soil carbon dynamics in a variety of settings throughout the Western United States. Specifically, the influence of soil development on carbon are being examined by measuring changes in mineral associations and mean residence time of organic carbon in soil chronosequences including glacial-fluvial terraces of the Cowlitz River, Wash., and Rock Creek, Mont., as well as marine terraces near Santa Cruz and Mattole, Calif., and Cape Blanco, Oreg. Natural climate gradients within and between these soil sequences allow for investigation of the influence of water on both soil development and carbon stabilization. Data from these chronosequences are integrated and synthesized using a coupled carbon-geochemical reactive transport model, which will allow for simulations of carbon cycling over a range of timescales.
Through this research we will develop a new modeling tool for investigating interactions of carbon, water, and eventually other nutrients in soils. Such a tool could be used to aid mapping of existing soil carbon storage across the landscape, predicting the response of soils to climate change, and evaluating the potential to sequester carbon in Western soils. In addition, the datasets generated through this study will help address several knowledge gaps in our basic understanding of the interaction between physical and biological controls of carbon and nutrient cycling in soils.
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Last modified: 16:08:29 Thu 13 Dec 2012