土壤微生物对气候变暖和大气N沉降的响应

气候变暖和大气N沉降是近一、二十年来人们非常关注的全球变化现象,它们所带来的一系列生态问题已成为全球变化研究的重要议题。它们不仅影响地上植被生长和群落组成,还直接或间接地影响土壤微生物过程,而土壤微生物对此做出的响应正是生态系统反馈过程中非常重要的环节。该文分别从气候变化对土壤微生物的影响(土壤微生物量、微生物活动和微生物群落结构)和土壤微生物对气候变化的响应(凋落物分解、养分利用与循环以及养分的固持与流失)两个角度,综述近期土壤微生物对气候变暖和大气N沉降响应与适应的研究进展。气候变暖和大气N沉降对土壤微生物的影响更多地反映在微生物群落的结构和功能上,而土壤微生物量、微生物活动和群落结构的变化又会通过改变凋落物分解、养分利用和C、N循环等重要的土壤生态系统功能和过程做出响应,形成正向或负向反馈,加强或削弱气候变化给整个陆地生态系统带来的影响。然而,到目前为止土壤微生物的响应对陆地生态系统产生的最终结果仍是未决的关键性问题。

SOIL MICROBIAL FEEDBACKS TO CLIMATE WARMING AND ATMOSPHERIC N DEPOSITION

Global warming, resulted from rising atmospheric greenhouse gases, has increased the Earth’s surface temperature by 0.6 ℃ in the 20th century and will continue to increase it by approximately 1.4-5.8 ℃ in this century. The delivery of reactive forms of nitrogen to the environment through the sum of agricultural and industrial activities also exceeds that from natural processes. The ecological consequences arising from global warming and atmospheric N deposition have also become the very important issues of global change research. These changes not only impact the growth of aboveground vegetation and plant community structure, but also change belowground soil environment, and thus indirectly influence the microbial processes. Recent researches suggest that soil microbial responses to climate warming and atmospheric N deposition play an important role in the feedbacks of terrestrial ecosystems to climate change. Better understanding on the microbial responses to increasing temperature and N deposition is critical to predict the changes in terrestrial ecosystem C, N dynamics in the future.From the viewpoints of microbial biomass, microbial activities and structure, litter decomposition, nutrient use and cycling, sequestration, retention and loss of nutrients, this article reviews recent advances research on microbial responses to climate warming and atmospheric N deposition. Consequence, taken from most of researches, shows that soil microbial community structure is more sensitive than soil microbial biomass and microbial activities to reflect global climatic change. Although much progress in research on impacts of climate warming and atmospheric N deposition on microbe has achieved, yet there are some questions unresolved: 1) amounts of short-term research cannot be used to predict the long-term influence of these global change drivers on microbe; 2) few researches on microbial turnover and interaction in nutrient cycling; 3) interactive effects among different global change drivers to soil microbe. Therefore, more efforts should be taken to study the long-term influence of these global change drivers on microbe and analyze the change in microbial process with soil environmental changes, and more attention should be paid to the microbial responses to global change drivers in natural ecosystems in future researches. In the near future, consequence of soil microbial response on global change will still be the key question that we should answer urgently.