[Investigation on effects of elevated atmospheric CO concentration on plant-soil system carbon cycling: Based on stable isotopic technique].

Elevated atmospheric CO affects plant photosynthesis process and biomass accumulation, furthermore alters the distribution of photosynthetic carbon (C) above- and below-ground. The formation and turnover of soil organic carbon (SOC) depends on the input of photosynthetic C, so the change of plant physiology and metabolism caused by increasing CO concentration will further affect the balance of SOC pool. Therefore, stable isotope C technique is powerful for clarifying the influence of elevated atmospheric CO on C cycling in plant-soil system, including the distribution of photosynthetic C among plant organs, and the transformation and accumulation of photosynthetic C in soil. This review summarized research focused on the effects of elevated atmospheric CO on C cycling in terrestrial ecosystems based on C natural abundance or C tracing technique, including: 1) isotopic fractionation effect in plant photosynthesis; 2) the distribution of photosynthetic C in plant organs; 3) the transformation and stabilization of photosynthetic C in SOC driven by microbial process. Clarifying the above processes and controlling mechanisms is essential to predict long-term influence of elevated CO on C cycling and evaluate the source-sink function of SOC in terrestrial ecosystems.