PROGRESS IN RESEARCH ON SOIL RESPIRATION UNDER THE GLOBAL CHANGE

Abstract

Soil respiration is the primary path by which CO 2 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 CO 2 , global warming, tillage cultivation changing, increasing deposition of nitrogen from the atmosphere. The rising concentrations of CO 2 in the atmosphere will increase the flux of soil CO 2 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 CO 2 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 CO 2 emission from soils. All of these global changes including the rising concentrations of CO 2, global warming, and etc. 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 CO 2 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 CO 2 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 CO 2, 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 CO 2 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 CO 2 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.