资源环境科技发展态势分析平台

We evaluated the effect on soil CO2 efflux (F-CO2) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to + 200 ppmv for 15 years. Five-day intervals of exposure to elevated CO2 (eCO(2)) ranging 1.0-1.8 times ambient did not affect F-CO2. F-CO2 did not decrease until 4 months after termination of the long-term eCO(2) treatment, longer than the 10 days observed for decrease of F-CO2 after experimental blocking of C flow to belowground, but shorter than the similar to 13 months it took for increase of F-CO2 following the initiation of eCO(2). The reduction of F-CO2 upon termination of enrichment (similar to 35%) cannot be explained by the reduction of leaf area (similar to 15%) and associated carbohydrate production and allocation, suggesting a disproportionate contraction of the belowground ecosystem components; this was consistent with the reductions in base respiration and F-CO2-temperature sensitivity. These asymmetric responses pose a tractable challenge to process-based models attempting to isolate the effect of individual processes on F-CO2.