Impacts of Soil Disturbance on Soil Respiration and Carbon Sequestration in Desert Scrublands: Implications for Utility-Scale Solar Energy Development

The recent interest in renewable energy has resulted in an explosion of utility-level solar plants, commonly constructed in arid and semi-arid regions where average solar irradiation is high. These regions are known to be significant carbon sinks and limited research has been done to understand the long-term effects of environmental disturbances. We’re studying vegetative species that are native to the environment, including Encelia farinosa (brittle bush flower), Ferocactus cylindraceus (Barrel cactus), and Cercidium floridum (Blue Palo Verde), which respectively use the C3, CAM, and C4 photosynthetic pathways. Remote CO2 sensors were placed in three different locations, each within the root ball of one of the three vegetative species. Our study analyzes soil from initial disturbance to time when it has reached equilibrium. CO2 measurements are being taken at 2, 8, and 16cm soil depth at 8-minute intervals continuously between the months of June to September 2012. Ancillary data recorded at each site included temperature and precipitation. Single site analyses will seek to relate the CO2 release to other environmental parameters, e.g. temperature. Inter-site comparisons will be based on a daily summary metric rather than individual 8-minute measurements. Using standard statistical techniques, we will look for patterns in soil respiration rates between the three different soil sites. Previously measured soil respiration rates range up to 60μg CO2-C mg soil d^-1 but these studies appear not to have established a correlation between respiration rates and photosynthetic types that may show how different vegetation cover implies different greenhouse-gas emission responses to soil disturbance