Contribution of root-associated microbial communities on soil quality of Oak and Pine forests in the Himalayan ecosystem

Microorganisms, the fundamental components of all the ecosystems, play significant role in various biological processes such as biodegradation, mineralization and nutrient mobilization. The role of rhizosphere associated microbial interactions with reference to their contribution in enzymatic activities in two dominant forest tree species of Indian Himalaya, namely Oak ( Quercus leucotrichophora ) and Pine ( Pinus roxburghii ), is focused in the present study. Rhizosphere soil and root samples were collected in active and dormant seasons for two consecutive years from three selected sites. Root samples were studied for colonization by fungal associates as indicator of their ecological functions. Soil samples were analyzed for physico-chemical characteristics and enzymatic activities as a measure of soil health. Dark Septate Endophytes (DSE) and fungal colonization were observed in roots of both the tree species. Microscopic observations revealed high percentage of DSE and fungal hyphae (76–96 and 32–78%) in Oak while in Pine roots this percentage was 8–10 and 48–86%, respectively. Most of the soil physico-chemical parameters were found higher in Oak soil except total phosphorus content. Further, activity of acid phosphatase and dehydrogenase was recorded higher in Oak soil as compared to Pine soil. Pine soil samples showed high alkaline phosphatase and β-glucosidase activities. The study concludes that microbial associations and their activities in Oak and Pine soils appeared to define the specific properties of both forest types in terms of slow biodegradation in Pine and higher carbon sequestration in Oak.