Microbial diversity and activity of disturbed soil in the northern Chihuahuan Desert |
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Authors: | X Liu William C Lindemann Walter G Whitford Robert L Steiner |
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Institution: | (1) Department of Agronomy and Horticulture, New Mexico State University, Box 3Q, Las Cruces, NM 88003, USA e-mail: xliu@nmsu.edu Tel: +1-505-5210864, MX;(2) USDA-ARS Jornada Experimental Range, Department 3JER, New Mexico State University Las Cruces, NM 88003, USA, MX;(3) University Statistics Center, 3CQ, New Mexico State University, Las Cruces, NM 88003, USA, MX |
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Abstract: | The effects of intense grazing, seasonal drought, and fire on soil microbial diversity (substrate utilization) and activity
in a northern Chihuahuan Desert grassland were measured in summer 1997, winter 1998, and spring 1998. Intense livestock grazing
was initiated in winter 1995, burning occurred in August 1994, and drought stresses were imposed from October 1994 to June
1997. Microbial diversity was inferred from the carbon substrate utilization patterns in both gram (+) and gram (–) Biolog
plates. Microbial activity was estimated by the activity of selected enzymes. Neither microbial diversity nor activity was
affected by grazing. The interaction of intense grazing and stress sub-treatments only occurred in spring for one set of diversity
measurements. The maximum microbial diversity and activity occurred in the winter-drought-stress sub-plots in summer and spring.
Burning reduced microbial diversity and most enzyme activities as compared to the control in summer and spring. Microbial
diversity was also lower in summer-drought-stress sub-plots than in the control in summer and spring. Microbial diversity
was highest in summer, intermediate in winter, and lowest in spring. Microbial activity was generally higher in summer and
lower in winter. It was concluded that substrate availability was the most important factor affecting the diversity and activity
of soil microorganisms within a season. Soil moisture was not the factor causing differences in microbial diversity and activity
among the stress treatments, but it was a predictor for some microbial responses under a particular stress.
Received: 12 August 1999 |
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Keywords: | Microorganisms Diversity Activity Grazing Stress |
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