PROGRESS IN GEOGRAPHY ›› 2009, Vol. 28 ›› Issue (3): 441-448.doi: 10.11820/dlkxjz.2009.03.018

• Original Articles • Previous Articles     Next Articles

Application and Prospect of Carbon Isotope in the Study of Carbon Cycle in Grassland Ecosystem

LUO Guangqiang1,2|GENG Yuanbo1|YUAN Guofu1   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Graduate University of Chinese Academy of Science, Beijing 100049, China
  • Online:2009-05-25 Published:2009-05-25

Abstract:

Study of grassland ecosystem is essential for understanding the allocation of global carbon pool and the global carbon cycle. In this paper, we reviewed briefly the main applications of carbon isotopes in grassland ecosystem in the following aspects: the sources of grassland soil organic carbon, the allocation of photosynthesized carbon in grassland, the turnover of soil organic matter and the study of soil respiration. The focus is on the application of carbon isotopes in the study of soil respiration. Soil respiration is a main way of carbon dioxide flux from soil to atmosphere, so its separation will contribute to the understanding of soil carbon cycle and carbon balance under the condition of global change. Several methods for separating soil respiration by the application of carbon isotopes have been reviewed including: ①13C natural abundance method,②pulse labeling methods, ③the isotope dilution method, ④the model rhizodeposition technique, ⑤modeling of 14CO2 efflux dynamics, ⑥the exudate elution procedure and ⑦the difference method between root-derived 14CO2 and rhizomicrobial 14CO2. There is no standard method and criterion for the separation of soil respiration until now. The temperature sensitivity of soil respiration is important for understanding terrestrial carbon cycling. Many studies recently showed that Q10 is a variable related to temperature, moisture and some other factors. Because most of the large-scale carbon cycle models are based on the temperature sensitivity, the accurate determination of Q10 value is essential in estimating carbon efflux in terrestrial ecosystems and predicting future climate change. Carbon isotope techniques involved less disturbance to the soil-plant system than other methods and had great potential in the study of carbon cycle of grassland ecosystem.

Key words: carbon cycle;soil respiration, carbon isotope, grassland ecosystem