全球变化条件下的土壤呼吸效应

土壤呼吸是陆地植物固定CO₂尔后又释放CO₂返回大气的主要途径，是与全球变化有关的一个重要过程。综述了全球变化下CO₂浓度上升、全球增温、耕作方式的改变及氮沉降增加的土壤呼吸效应。大气CO₂浓度的上升将增加土壤中CO₂的释放通量，同时将促进土壤的碳吸存；在全球增温的情形下，土壤可能向大气中释放更多的CO₂，传统的土地利用方式可能是引发温室气体CO₂产生的重要原因，所有这些全球变化对土壤呼吸的作用具有不确定性。认为土壤碳库的碳储量增加并不能减缓21世纪大气CO₂浓度的上升。据此讨论了该问题的对策并提出了今后土壤呼吸的一些研究方向。其中强调，尽管森林土壤碳固定能力有限，但植树造林、森林保护是一项缓解大气CO₂上升的可行性对策；基于现有田间尺度CO₂通量测定在不确定性方面的进展，今后应继续朝大尺度田间和模拟程序方面努力；着重回答全球变化条件下的土壤呼吸过程机理；区分土壤呼吸的不同来源以及弄清土壤呼吸黑箱系统中土壤微生物及土壤动物的功能。当然，土壤呼吸的测定方法尚有待改善。

PROGRESS IN RESEARCH ON SOIL RESPIRATION UNDER THE GLOBAL CHANGE

Soil respiration is the primary path by which CO₂ fixed by land plants returns to the atmosphere, and a key process in relation to the global change. The objective of this paper is to provide a brief scientific review on the effects of soil respiration in the circumstances of rising concentrations of CO₂, global warming, tillage cultivation changing, increasing deposition of nitrogen from the atmosphere. The rising concentrations of CO₂ in the atmosphere will increase the flux of soil CO₂ emission, while it will prompt the potential of soil carbon sequestration. Organic matter decomposition is likely to be stimulated more than net primary productivity (NPP), which would lead to the release of more CO₂ from the soil to the atmosphere in the event of global warming. The traditional land uses of China probably result in declines of soil organic carbon, much of this loss in soil organic carbon can be attributed to tillage effects which cause more CO₂ emission from soils. All of these global changes including the rising concentrations of CO₂, global warming, and WTBX]etc.WT] are playing an ambiguous role in the sequestering of organic carbon by soils. Summary showed that a large increase in the soil carbon pool seems unlikely to moderate the rise in atmospheric CO₂ during the 21th century. the strategies were discussed in terms of this problem, and some emphases of further study in this field were suggested. It emphasizes that forest would be act as a good media of soil carbon sequestration in spite of its limited capacity of sequestrating soil carbon, expanding afforestation and forest protection would be an effective method to mitigate the rising of CO₂ in the atmosphere. Further study to soil respiration should focus on the followings:
(1) There is large temporal and spatial variability in the soil atmosphere exchange of CO₂, as impacted by global change on global scale. Based on the progress on the decreasing the uncertainty of field scale flux measurements, Much effort should be made and direct to large scale field and modeling programs
(2) For the high complexity of global change which impacts on soil respiration, in natural ecosystems, there is much uncertainty which long term rising CO₂ concentrations how to effect ecosystem. So soil processes of soil respiration under global change is a key question should be answered.
(3) Soil respiration is originated from a black box, partitioning soil CO₂ emissions by source (soil organic matter mineralization, litter decomposition, root respiration ) is difficult. The contribution of each group needs to be understood to evaluate implications of global change on soil carbon cycling and sequestration. And much attention will be paid to soil microbes and soil fauna. First of all, methods of the measurement of soil respiration should be improved. 