ZHOU Jizhong, SOE professor of Global Recruitment Program, published a paper entitled Stochasticity, Succession and Environmental Perturbations in a Fluidic Ecosystem with his group in Proceedings of the National Academy of Sciences (PNAS) on line on February 18, 2014, proposing a new conceptual framework of ecological succession law. The importance of stochastic processes in the ecological succession is also verified in this study. Prof. ZHOU is the first and the corresponding author.
Prof. ZHOU Jizhong proposed that the physical characteristics of an ecosystem had dramatic impacts on its succession. The community dispersal is significantly restricted in a non-fluidic ecosystem, resulting in a weaker stochasticity than that of a fluidic ecosystem. In general, environmental perturbations have beenclassified into two categories: 1) nutrient input, which is believed to increase compositional stochasticity; 2) disturbances, which is believed to decrease compositional stochasticity. In addition, the persistence of environment change is also an important factor. Because the ecosystems are flexible to the non-permanent environmental changes, their responses to those changes are inconsistent. Considering all these factors, the relative importance of stochastic and deterministic processes is theoretically predictable.
Microbial community succession in bioremediationprocess of heavy mental contaminatedgroundwater system
The framework was then tested with a groundwater system contaminated by heavy metal. With 269-day’s continuous detection of the bioremediation process of the groundwater system, the group found that stochastic processesplay important roles in controlling the microbial community succession. During the early-to-mid phase of the succession, the roles of stochastic processes in controlling community composition increase substantially from 81.3% to 92.0%. At the final phrase of the succession, as the environmental perturbations disappeare gradually, deterministic processes become more important. Therefore, understanding the relative importance of stochastic and deterministic processes is dynamic rather than static. The data in this study are consistent with the proposed conceptual framework but contradictory to conventional wisdom.
The conceptual framework for ecological succession is significant for predicting the responses of ecosystems to environmental change and protecting the biodiversity.