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Soil respiration, which is almost the only output approach for carbon dioxide exchanges in soils between the global terrestrial ecosystem and the atmosphere, exerts a direct influence on the speed of carbon turnover rate of the soil. On a global scale, soil respiration from terrestrial ecosystems is more than ten times the CO2 released from fossil fuel combustion and the reservoir of soil organic carbon in the terrestrial ecosystems is almost three times that of atmospheric carbon reservoir, a subtle change in soil respiration in response to environmental change might produce marked impacts on global carbon budget and the atmospheric CO2 concentration. In light of the increasing trend of global warming, the changes in global land use and land cover approaches might weaken the carbon sink capacity of the terrestrial ecosystem as well as enhance soil respiratory intensity at the same time. In contrast, the terrestrial ecosystem carbon sink capacity would be upgraded if proper policy is adopted for carbon management of the terrestrial ecosystem and the relevant technologies for enhancing the carbon sink are introduced. It is more important to understand the biogenic and environmental process of soil respiration to evaluate the global carbon budget.
The grassland is one of the most important vegetation types in China, making up about 40% of the nation's territory. It is one of the most essential carbon pools of China's terrestrial ecosystem. In cooperation with the international scientific joint program, research team led by Dr. DONG Yunshe from the CAS Institute of Geographical Sciences and Natural Resources Research has carried out studies on soil respiration process of China's temperate steppes since 2000.
By conducting large-scale measurement in temperate steppe using the same experimental methods and by multi-point, long-time and consecutive field observation, the researchers achieved a better understanding of the soil respiration process, including temporal and spatial changes and regional variation of respiration flux of chosen representative steppes, the comprehensive mechanism of environmental factors influencing the soil respiration process, their coupling relations with soil respiration, and proportional relations and dynamic changes between the soil microbe respiration and root respiration in the entire soil respiration of the grassland ecosystem. Their work lays solid a scientific foundation for the evaluation and prediction of the contribution of carbon emission in China's terrestrial ecosystems to the global carbon cycle, and provides complement to the terrestrial carbon cycle experiment in China.