[Effects of different tea plantation ages on soil microbial community structure and diversity]

We investigated the effects of tea plantation age on soil microbial community structure and diversity with surface and subsurface soil samples (0-20 and 20-40 cm) from tea plantation at different ages (0, 20, 25, 38 and 48 years). We analyzed soil bacterial and fungal communities by terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR techniques. The results showed that soil physicochemical properties changed significantly after planting tea. The contents of soil organic carbon, available nitrogen, and available phosphorus increased at first, and gradually decreased with the increases of tea plantation age. The contents of organic carbon and total nitrogen in the topsoil were significantly higher than those in the subsoil. Moreover, soil bacterial community composition varied across tea plantation age. Bacterial diversity index decreased with increasing tea plantation age. The composition and diversity of soil fungal communities did not show a clear relationship with the tea plantation age. Overall, soil bacterial communities was more sensitive to the tea plantation age than fungal communities. With the increases of tea plantation age, the ratio of soil fungi to bacteria showed increasing trend. Soil microbial community in the tea plantation changed from a "bacterial type" with low fungi/bacteria ratio (F/B) to a "fungal type" with high F/B.