Seasonal Changes of Microbiological Properties in Steppe Soils from Degraded Arid Area in Tunisia

Abstract

There is growing interest in assessing soil quality using microbial properties in desertified areas. A study was conducted in arid soils subjected to desertification in the south of Tunisia to illustrate the effects of dominating steppes of Stipa tenacissima and Anthyllis sericea subsp. henoniana on soil chemical, microbial, and biochemical properties. Soil samples were collected beneath the canopy of S. tenacissima, A. sericea subsp. Henoniana, and open areas in the rainy and dry seasons. These steppes showed higher values of soil organic carbon content (Corg). Microbial biomass carbon (Cmic) was also greater under steppes and reached 289 μg C g−1 soil under Anthyllis canopies. Studied enzyme activities (dehydrogenase, phosphatase and β-glucosidase) increased greatly beneath steppes showing dehydrogenase activity of 159 μg INTF g−1 soil d−1, while it did not reach 36 μg INTF g−1 soil d−1 in open areas. Conversely, lower values of C/N ratio and metabolic quotient (qCO2), particularly in the vicinity of A. sericea subsp. henoniana. The environmental conditions significantly affected studied properties: the soil organic carbon, microbial biomass, and enzyme activities were reduced in dry season, while C/N ratio and qCO2 were higher. Our results suggest the importance of vegetation cover in regulating soil microbial processes in arid degraded areas and that the wet season may play an important role in driving seasonal changes in microbial biomass and activity.