Soil Microbial Activity is Stabilized by Mesquite in Recreational Campsites

Abstract

Recreational camping often suppresses vegetation cover and expands bare ground. These shifts have important implications for plant and soil ecological health. Soil microbial activity can inform understanding of how recreation affects ecological processes. This case study uses campsites at the Santa Rita Experimental Range in Southern Arizona to test the hypothesis that the degrading impacts of camping on vegetation are mirrored in the soil microbiome. Measurements of herbaceous basal cover, microbial biomass, and enzyme activity were collected and stratified by categories of camping disturbance and mesquite (Prosopis velutina) cover. Campsites demonstrated suppressed litter, herbaceous cover, and gravimetric water content. Herbaceous cover was 53% lower in campsites than in undisturbed areas. Surprisingly, enzyme activity and microbial biomass C and N were more influenced by mesquite canopy (microbial biomass C by 55% and microbial biomass N by 52%) than by camping disturbance. In spite of observed evidence that campsite soil environments are degraded, mesquite-driven ecological processes appear to stave off degradation of soil microbial activity. However, soil microbial biomass and enzyme activity are indirectly affected by camping disturbance through the combined influence of litter, herbaceous cover, and soil moisture. Therefore, plant-soil feedbacks play an important function in determining how campsites in semiarid systems respond to disturbance.