Carbon and Nitrogen Stocks in the Salt Lake Valley Urban Ecosystem
Abstract
Water availability exerts a fundamental control over primary production processes in both managed and unmanaged arid land ecosystems. Societal interest in converting grasslands to urban forest has likely increased primary productivity in many western US cities. The changes in primary productivity have the potential to alter C and N stocks of urban soils. Here, we report on trends in soil C and N storage observed along an urban age gradient spanning a century in the Salt Lake Valley, USA metropolitan area. Our results indicate substantial accumulation of soil organic C and total N beneath residential lawns in this semi-arid region. Soil organic C and total N stocks in the upper 20 cm of lawn soils increased as much as 3-fold following long-term residential use. Average tree biomass of residential parcels increased quickly with age, creating urban forests with standing biomass values similar to nearby coniferous forests. Anthropogenic influence emerged as the dominant source of variation in these stocks across our study area, eclipsing site characteristics such as soil texture and elevation that are commonly important in natural settings. While US cities are prominent exporters of atmospheric C and reactive N, significant gains in C and N stocks may offset a portion of these outputs in well-irrigated cities in dry climates. Observations of regional C and N storage in western US cities should lead to better estimates of sequestration capacities and provide insights into the potential consequence of future water-use policies, including xeriscaping.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.B41D..05W
- Keywords:
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- 0428 Carbon cycling (4806);
- 0439 Ecosystems;
- structure and dynamics (4815);
- 0469 Nitrogen cycling;
- 0486 Soils/pedology (1865);
- 0493 Urban systems