Indicators of Ecosytem Health and the Impact of Mineralized Terrain.

Studies of soil quality and ecosystem health employ a wide variety of approaches designed to monitor ecosystem functioning within an array of natural and anthropogenic disturbances. Definitions of soil health vary, but typically include the soil’s role in mediating nutrient, water, and energy cycles in support of associated flora and fauna. The limited mobility and inherent sensitivity of soil microbial communities to external stressors makes them potentially well suited for the study of stressors on ecosystem health. Additional measures of plant community characteristics can provide a more complete picture of the impact of a natural or anthropogenic disturbance on an ecosystem due in part to the roles of vegetation in phytoremediation, the hydrologic cycle, and nutritional value to fauna. This study is focused on metal-microbe-vegetation interactions in mineralized terrestrial ecosystems, and impacts on ecosystem functioning. Relationships among microbial and plant activity and composition, and abiotic soil parameters will be used to develop ecosystem health indices that could be used in support of geoenvironmental assessments and reclamation monitoring for example. An extensive reconnaissance study within several Western U.S. mining districts of contrasting mineralogy and climate is underway, examining the differences in metal- biogeochemical interaction between mineralized and adjoining non-mineralized areas in various ecosystems. Study areas include a sage-grassland site impacted by copper/molybdenum (Battle Mt. District, NV); an oak-pine-grass site impacted by nickel/chromium (Red Hills ACEC, CA); and two sage-pinyon-juniper sites impacted by acid-sulfate mineralization (Castle Peak District, NV; Masonic District, NV). Preliminary data will include 1) soil biota: microbial biomass (PFLA), enzyme activity (FDA hydrolysis), functional diversity (Biolog Ecoplate), and C/N mineralization potential (lab incubation); 2) vegetation: density, cover, biomass; and 3) soil abiotic measures: total and bioavailable metals, pH, texture, electrical conductivity, and bulk density.