| Functional diversity of the soil microbial community is commonly used to describe soil health. Microenvironment heterogeneity in environmental stresses, including anthropogenic-induced heterogeneity, may induce reversible or irreversible changes in genetic and functional diversity. Functional redundancy in a microbial population may mitigate variability in genetic diversity. Thus, it is unclear at what point human activity may affect functionality of soil microbial consortia and how this may relate to changes in microbial population diversity. I evaluated the impact of anthropogenic environmental impacts associated with extensive grazing and natural gas extraction, common in the and Southwestern United States, on the total microbial diversity profiles and the total soil catabolic profiles as described by carbon substrate induced respiration. Total bacterial diversity was evaluated by 16S-based tag-encoded FLX amplicon pyrosequencing (bTEFAP) modified to use the Titanium sequencing platform. Substrate induced respiration, measured using the MicroRespTM system, was evaluated for various relevant carbon sources (simple and polymeric sugars, amino acids, carboxylic acids, and fatty acids). Results indicate that under the tested scenarios cyanobacteria and some microfungal communities are nearly eliminated; the diversity of the other bacterial taxa was similar across disturbance regimes, indicating bacterial resilience and persistence in arid soils. Microbial activity was greatest and most variable in sites exposed to disturbance (grazing, natural gas extraction) suggesting that higher functional diversity is a population level adaptation to the disturbance. |
