There are diverse micro-organism species live in soil. Understanding the mechanism in Maintaning such diversity is the core target of Microbial ecology. It is known that both deterministic processes such as competitive exclusion and environment filtering and stochastic processes such as birth / death and dispersal/ colonization affect the assembly of soil microbial communities.Little has been known on how the anthropogenic environment changes affect these processes.
Dr ZHANG Ximei and coworkers in Ecological Stoichiometry Research Group of IAE, using a method newly developed by the group, have proved that 16 different environment changes such as lose in plant diversity, grazing, nitrogen precipitation, phosphorus addition, increase in rainfall, temperature and their combination primarily affect microbial community by stochastic process rather than deterministic processes. The results are contradictory to the traditional theory that the deterministic process is dominant. The results were published in Global Change Biology.
In another work on soil microbial diversity, Dr ZHANG Ximei and coworkers distinguished the relative contributions of ecological and evolutional process to soil microbial diversity. Soil acidity (pH) is the most important influencing factor to soil microbes. On One side, the environmental changes may filter out species those could not adapt to the environment. On the other side, species could adapt to the new environment by evolution process or the endemic species already adapted to the acidic pressure may colonize the acidified soils through dispersal. So, there are 3 potential mechanisms. However, neither ecological filtering nor adaptive evolution operate alone. The effect of ecological filtering is partly counteracted by adaptive evolution. The terrestrial ecosystem was originated from marine ecosystem. The primitive soil is neutral. The long term geochemical process led some ecosystem gradually acidified. Scientists investigated soil acidification process, its effect on the changes in soil microbial diversity and the relative contributions of ecological filtering and evolutional adaptation to the microbial biodiversity. The investigation led to a theoretical frame to demonstrate 7 combinations of these 2 processes in 2 time scales and predicted corresponding diversity patterns. The mechanism may be deduced according to real pattern of diversity. It was found that all 3 mechanisms operate. Different bacterial phyla/classes were governed by different type of mechanisms. The 3d one is the dominant type. The results were published in Soil Biology and Biochemistry.