Role of perennial plants in determining the activity of the microbial community in the Negev Desert ecosystem

Perennial plants are known to be one of the most influential parameters in desert ecosystems affecting microbial activity. In this study, we examined the importance of these perennial shrubs and attempted to determine the most influential factor that contributes the most to the ecosystem by separating the physical part and the organic contribution of perennial plants. The study site is located in the northern Negev Desert, Israel, where 50 Hammada scoparia shrubs and 50 artificial plants were randomly marked to be used as a tool for the above objectives. Soil samples were collected monthly in the vicinity of the canopies of both shrubs while control samples were collected from the open areas between the shrubs. All samples were collected from the upper (0-10 cm) and the deeper (10-20 cm) soil layers. The contribution to microbial activity was measured by evaluation of the microbial community functions in soil. The results of the research showed a trend of a strong influence of the perennial H. scoparia shrubs on microbial community function. The functional aspects of the microbial community that were measured were CO2 evolution, microbial biomass, microbial functional diversity, and the physiological profile of the community. High values for all parameters were observed under the vicinity of the H. scoparia shrubs, while the artificial plants were found to have a weaker effect on the community according to soil depth. The upper-soil layer at both locations (artificial plant canopy and control samples) showed higher values of the functioning parameters than that of the deeper soil layer. The results indicate the importance of the organic contribution (plant litter) in comparison to the physical part of desert shrubs. (c) 2008 Elsevier Ltd. All rights reserved.