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United States Department of Agriculture

Agricultural Research Service

Title: Microbial Communities of a Native Perennial Bunchgrass Do Not Respond Consistently Accross a Gradient of Land Use Intensification

Authors
item Steenwerth, Kerri
item Jackson, Louise - UCDAVIS,LAND,AIR,WATER RE
item Carlise, Eli - UCDAVIS, VIT & ENOLOGY
item Scow, Kate - UCDAVIS,LAND,AIR,WATER RE

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2005
Publication Date: March 20, 2006
Citation: Steenwerth, K.L., Jackson, L.E., Carlise, E.A., Scow, K.M. 2006. Microbial communities of a native perennial bunchgrass do not respond consistently accross a gradient of land use intensification. Soil Biology and Biochemistry. Vol. 38, 1797-1811.

Interpretive Summary: To test if native perennial bunchgrasses cultivate the same microbial community composition across a gradient in land use intensification, soils were sampled in three seasons in areas under bunchgrasses ('plant') and in bare soils ('removal') in which plots were cleared of living plants adjacent to native perennial bunchgrasses (Nassella pulchra). Samples were collected at sites representing a gradient in land use intensification: a relict perennial grassland, a restored perennial grassland, and a perennial grass agriculture site. Perennial bunchgrasses in the relict perennial grassland had greater effects on soil resource pools than the other two sites. In addition, land use history limits the similarity of microbial community composition as well as soil C and N dynamics among sites. Furthermore, different microbial PLFA markers were associated with N. pulchra in each land use type, indicating that the same plant species does not retain a unique microbial fingerprint across the gradient of land use intensification. This study highlights the necessity to preserve relict stands of perennial bunchgrasses to retain linkages between unique above and belowground processes.

Technical Abstract: To test if native perennial bunchgrasses cultivate the same microbial community composition across a gradient in land use intensification, soils were sampled in fall, winter and spring in areas under bunchgrasses ('plant') and in bare soils ('removal') in which plots were cleared of living plants adjacent to native perennial bunchgrasses (Nassella pulchra). Samples were collected in a relict perennial grassland, a restored perennial grassland, and a perennial grass agriculture site. An exotic annual grassland site was also included since perennial bunchgrasses often exist within a matrix of annual grasses in California. Differences in soil resource pools between 'plant' and 'removal' soils were observed mainly in the relict perennial grassland and perennial grass agriculture site. Seasonal responses occurred in all sites. Microbial biomass C and dissolved organic C were greater under perennial bunchgrasses in the relict perennial grassland and perennial grass agriculture when comparing treatment means of 'plant' vs. 'removal' soil. In general, soil moisture, microbial respiration, and nitrate decreased from fall to spring in 'plant' and 'removal' soils, while soil ammonium and net mineralizable N ('plant' only) increased. A canonical correspondence analysis (CCA) of PLFA profiles from all sites showed that land use history limits the similarity of microbial community composition as well as soil C and N dynamics among sites. When PLFA profiles from individual sites were analyzed by CCA, different microbial PLFA markers were associated with N. pulchra in each site, indicating that the same plant species does not retain a unique microbial fingerprint across the gradient of land use intensification.

Last Modified: 11/28/2014
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