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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGING LIMITED IRRIGATION AND RAINFALL FOR CROP PRODUCTION IN SEMI-ARID ENVIRONMENTS

Location: Wind Erosion and Water Conservation Research

Title: Soil microbial community response to drought and precipitation variability in the Chiuahuan Desert

Authors
item Clark, Jeb - TTU
item Campbell, James - TTU
item Grizzle, Heath - TTU
item Acosta-Martinez, Veronica
item Zak, John - TTU

Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2008
Publication Date: February 1, 2009
Citation: Clark, J.S., Campbell, J.H., Grizzle, H., Acosta Martinez, V., Zak, J. 2009. Soil microbial community response to drought and precipitation variability in the Chiuahuan Desert. Microbial Ecology. 57(2): 248-260.

Interpretive Summary: As patterns of moisture inputs and amounts experience global change, soil microbial communities will be impacted, which can influence the functioning of the Chihuahuan desert region of West Texas. Scientists from Texas Tech University and USDA-ARS in Lubbock have examined the soil microbial community structure within three zones with an elevation and vegetation gradient (low desert-scrub, grassland, and high elevation oak-pine forests) along the Pine Canyon Watershed in Big Bend National Park at the Chihuahuan desert. This study identified significant differences in the soil microbial communities of the vegetation zones studied and as affected by seasonal changes. The differential susceptibility of the microbial communities to changes in precipitation amounts along the elevation gradient reflects the interactive effects of the soil moisture window duration following a precipitation event and differences in soil heat loads.

Technical Abstract: Increases in the magnitude and variability of precipitation events have been predicted for the Chihuahuan desert region of West Texas. As patterns of moisture inputs and amounts experience global change, soil microbial communities will be impacted, which can influence the functioning of the Chihuahuan desert. This study examined the soil microbial community structure within three zones with an elevation and vegetation gradient (low desert-scrub, grassland, and high elevation oak-pine forests) along the Pine Canyon Watershed in Big Bend National Park at the Chihuahuan desert. This study identified significant differences in the soil microbial communities of the vegetation zones studied and as affected by seasonal changes. Highest fungal levels were obtained in the low desert-scrub site and not from the high elevation oak-pine forests. Total bacterial and actinomycetes were higher in winter than in summer at the low elevation desert-shrub and grassland. DGGE band counts of amplified soil bacterial DNA differed significantly across sites and season showing this trend: mid-elevation grassland> low desert-scrub>high elevation oak-pine forest. Soil bacterial communities at the mid-elevation grassland were the most vulnerable to changes in precipitation frequency and timing, while fungal community structure was most vulnerable in the low-desert scrub site. The differential susceptibility of the microbial communities to changes in precipitation amounts along the elevation gradient reflects the interactive effects of the soil moisture window duration following a precipitation event and differences in soil heat loads. Amounts and types of carbon inputs may not be as important in regulating microbial structure among vegetation zones within in an arid environment as is the seasonal pattern of soil moisture and the soil heat load profile that characterizes the location.

Last Modified: 4/19/2014