Soil Water Cycling Links to Carbon Content between Ecosystems in the Colorado Front Range
Abstract
Near surface soil-water content is crucial to the sustainability of an ecosystem. Additionally, the feedbacks between soil water and soil carbon improve the ability to predict carbon sequestration rates. Organic-carbon content in surface soils influences soil texture and, subsequently, water holding capacity. Preliminary research for two growing seasons (2010 and 2011) compares soil water, temperature, heat flux, and evapotranspiration (ET) with soil organic carbon content at several sites in the Colorado Front Range. Continuous measurements of precipitation, soil moisture and temperature, and energy fluxes were conducted from eddy covariance flux towers at three sites around metropolitan Denver: one urban site and two adjacent sites, a montane forest (Flying J Ranch Open Space), and a native tallgrass prairie (Rocky Flats National Wildlife Refuge (NWR)). Irrigation data were obtained for the Denver urban site and added to its precipitation to obtain total water inputs. Soil samples (0-5cm) were collected at each tower site and analyzed for bulk density, volumetric water content, and organic carbon content. Soil water inputs and losses (as ET) were analyzed for each site and compared to soil organic carbon content. Rocky Flats NWR soils contained the highest organic carbon content (20-30 percent), while the urban site and Flying J Ranch soils contained between 10-15 percent. Comparing grassland sites, the urban soil received 5 times higher water input (600mm, more than half from irrigation) in 2010 than those of Rocky Flats. Despite less water input, the Rocky Flats site developed more soil organic carbon, possibly due to large amounts of grassland biomass mineralization and moderate soil moisture conditions through the season. The Denver urban site demonstrated less soil moisture variability in response to surface-water inputs from precipitation compared to soils at the native grassland and montane sites, perhaps limiting the conditions under which soil carbon formation can occur in urban soils. Broader research into water and carbon cycling in the Colorado Front Range has included remote sensing and leaf area index (LAI) measurements. Aerial high resolution hyperspectral (HSI) data were also collected over the 2010 growing season and high resolution multispectral (MSI) satellite data were collected for the 2011 growing season for both the Denver urban and Rocky Flats sites. In-situ LAI values will be used to calibrate remote sensing derived Vegetation Indices (VI), which may be used to extend geographical mapping of soil water dynamics by proxy. Plans include expanding the use of remote sensing and applying and refining research results with ecosystem process models to increase the scale to landscape levels and increase predictability under different land management and climate scenarios.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.B41C0225P
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0486 BIOGEOSCIENCES / Soils/pedology;
- 1631 GLOBAL CHANGE / Land/atmosphere interactions;
- 1865 HYDROLOGY / Soils