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United States Department of Agriculture

Agricultural Research Service

Title: Soil Carbon and Nitrogen in a Great Basin Pinyon-juniper Woodland; Influence of Vegetation, Burning, and Time

Authors
item Rau, Benjamin - UNIV. OF NEVADA RENO
item Johnson, Dale - UNIV. OF NEVADA RENO
item Blank, Robert
item Chambers, Jeanne - USDA-FOREST SERVICE-RMRS

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 16, 2008
Publication Date: January 30, 2009
Citation: Rau, B.M., Johnson, D.W., Blank, R.R., Chambers, J.C. 2009. Soil carbon and nitrogen in a Great Basin pinyon-juniper woodland: Influence of vegetation, burning, and time. Journal of Arid Environments. 73(2009):472-479.

Interpretive Summary: Increasing woodland cover in the intermountain western U.S. may increase carbon storage; however, knowledge is limited about the distribution of carbon on these landscapes, especially below ground pools. Our objectives were to quantify the spatial distribution of soil carbon in expansion woodlands, and to determine prescribed fire’s effect on soil C and N in a pinyon-juniper woodland. Prescribed burning caused immediate increases in surface soil C and N concentration, but over intermediate to longer periods of time no statistically detectable change in soil C or N content occurred from burning.

Technical Abstract: Much of the Great Basin, U.S. is currently dominated by sagebrush (Artemisia tridentate ssp. (Rydb.) Boivin) ecosystems. At intermediate elevations, sagebrush ecosystems are increasingly influenced by pinyon (Pinus monophylla Torr. & Frém.) and juniper (Juniperus osteosperma Torr.) expansion. Some scientists and policy makers believe that increasing woodland cover in the intermountain western U.S. will create new carbon storage on the landscape; however, little is currently known about the distribution of carbon on these landscapes. This is especially true of below ground pools. Our objectives were to quantify the spatial distribution of soil carbon in expansion woodlands, and to determine prescribed fire’s effect on soil C and N. We looked at two treatments (control and burn), three microsites (undertree, undershrub, and interspace), and four soil depths (0-8, 8-23, 23-38, and 38-52 cm). The study was conducted over a six-year period with one year pre-fire and five years post-fire data. Results for both carbon and nitrogen were similar, indicating the close relationship between the two elements in this ecosystem. Undershrub microsites had higher soil C and N concentrations than interspace and undertree microsites; however, under tree microsites had higher C:N ratio than interspace and undershrub microsites. Carbon and nitrogen concentration tended to decrease with increasing depth. Prescribed burning caused immediate increases in surface soil C and N concentration, but over intermediate to longer periods of time no statistically detectable change in soil C or N content occurred from burning.

Last Modified: 11/26/2014
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