Carbon and nitrogen limitations of soil microbial biomass in desert ecosystems |
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Authors: | Antonio Gallardo William H Schlesinger |
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Institution: | (1) Departamento de Ecologia, Universidad of Sevilla, Apdo. 1095, 41080 Sevilla, Spain;(2) Present address: Department of Botany, Duke University, Durham, NC 27706, USA;(3) Departments of Botany and Geology, Duke University, Durham, NC 27706, USA |
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Abstract: | Microbial biomass nitrogen was measured in unamended (dry) and wetted soils in ten shrubland and grassland communities of
the Chihuahuan desert, southern New Mexico, by the fumigation-extraction method. Microbial biomass-N in dry soils was undetectable.
Average microbial biomass-N in wetted soils among all plant communities was 15.3 μg g-1 soil. Highest values were found in the communities with the lowest topographic positions, and the minimum values were detected
in the spaces between shrubs. Microbial biomass was positively and significantly correlated to soil organic carbon and extractable
nitrogen (NH4
+ + NO3
-). In a stepwise multiple regression, organic carbon and extractable nitrogen accounted for 40.9 and 5.6%, respectively, of
the variance in microbial biomass-N among all the samples. Among communities, the soil microbial biomass was affected by the
ratio of carbon to extractable nitrogen. Our results suggest a succession in the control of microbial biomass from nitrogen
to carbon when the ratio of carbon to nitrogen decreases during desertification. |
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Keywords: | microbial biomass-N desert carbon nitrogen shrubland grassland playa |
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