Abstract
AbstractFunctional diversity of the soil microbial community is commonly used in the assessment of soil health as it relates to the activity of soil microflora involved in carbon cycling. Soil microbes in different microenvironments will have varying responses to different substrates, thus catabolic fingerprint information of each location-specific community can be obtained. The purpose of this study was to evaluate total-soil enzymatic activity profiles across three disturbance regimes in an arid desert grassland in the Southwestern United States. Microbial enzymatic activity was measured using the MicroResp™ system, which measures respiration of microbes within whole soil samples supplemented with various carbon sources (simple and polymeric sugars, amino acids, carboxylic acids, and fatty acids - tests run in the absence of light). Total bacterial diversity was assessed by 16s DNA pyrosequencing. Microbial activity was greatest and most variable in sites exposed to disturbance (grazing, natural gas extraction). Decoupling the C cycle from the C-fixing cyanobacteria may induce more diverse C uptake pathways associated with a more diverse microbial population. Similarities in taxonomic diversity and C substrate utilization patterns show that, for arid lands, any degradation-enhanced heterogeneity in soil’s biotic and abiotic parameters may drive changes in soils towards higher functional diversity to adapt to the disturbance.
Highlights
Functional diversity of the soil microbial community is commonly used in the assessment of soil health as it relates to the activity of soil microflora involved in carbon cycling
Community level physiological profiling The first obvious observation is that the CLPPSIR tests produced least respiration in the undisturbed soil samples including the crust and the subsoil samples
Carbohydrates increased the respiration of soil crust while organic acids did induce some activity in the noncrust undisturbed surficial soils
Summary
Functional diversity of the soil microbial community is commonly used in the assessment of soil health as it relates to the activity of soil microflora involved in carbon cycling. Soil microbes in different microenvironments will have varying responses to different substrates, catabolic fingerprint information, via substrate induced respiration, of each locationspecific community can be obtained These profiles are commonly used to assess the fertility potential and soil health under variable management or soil degradation scenarios. Arid land soils are exposed to extreme and highly variable abiotic stresses uncommon to most soils where on which Community Level Physiological Profiling (CLPP) by substrate induced respiration (SIR) methods are usually employed. This led to extremely specialized microbial consortia and associated metabolic activities with the heterotrophic activities in the surface cryptobiotic crust often dominating the system. Any activity that disturbs this crust is expected to have severe impacts on soil activity potential
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