Cernusak Lucas A, Winter Klaus, Dalling James W, Holtum Joseph A M, Jaramillo Carlos, K Rner Christian, Leakey Andrew D B, Norby Richard J, Poulter Benjamin, Turner Benjamin L, Wright S Joseph
School of Marine and Tropical Biology, James Cook University, Cairns, Qld 4878, Australia.
Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancon, Republic of Panama.
Funct Plant Biol. 2013 Jul;40(6):531-551. doi: 10.1071/FP12309.
Elevated atmospheric CO2 concentrations (ca) will undoubtedly affect the metabolism of tropical forests worldwide; however, critical aspects of how tropical forests will respond remain largely unknown. Here, we review the current state of knowledge about physiological and ecological responses, with the aim of providing a framework that can help to guide future experimental research. Modelling studies have indicated that elevated ca can potentially stimulate photosynthesis more in the tropics than at higher latitudes, because suppression of photorespiration by elevated ca increases with temperature. However, canopy leaves in tropical forests could also potentially reach a high temperature threshold under elevated ca that will moderate the rise in photosynthesis. Belowground responses, including fine root production, nutrient foraging and soil organic matter processing, will be especially important to the integrated ecosystem response to elevated ca. Water use efficiency will increase as ca rises, potentially impacting upon soil moisture status and nutrient availability. Recruitment may be differentially altered for some functional groups, potentially decreasing ecosystem carbon storage. Whole-forest CO2 enrichment experiments are urgently needed to test predictions of tropical forest functioning under elevated ca. Smaller scale experiments in the understorey and in gaps would also be informative, and could provide stepping stones towards stand-scale manipulations.
大气中二氧化碳浓度（ca）升高无疑会影响全球热带森林的新陈代谢；然而，热带森林将如何响应的关键方面在很大程度上仍不为人知。在此，我们综述了有关生理和生态响应的当前知识状态，旨在提供一个有助于指导未来实验研究的框架。模型研究表明，ca升高在热带地区可能比在高纬度地区更能刺激光合作用，因为ca升高对光呼吸的抑制作用随温度升高而增强。然而，在ca升高的情况下，热带森林的冠层叶片也可能达到一个高温阈值，这将缓和光合作用的增加。地下响应，包括细根生产、养分觅食和土壤有机质处理，对于生态系统对ca升高的综合响应尤为重要。随着ca升高，水分利用效率将提高，这可能会影响土壤湿度状况和养分有效性。某些功能组的更新可能会有不同程度的改变，这可能会减少生态系统的碳储量。迫切需要进行全林二氧化碳富集实验，以检验ca升高条件下热带森林功能的预测。在林下和林窗进行的较小规模实验也将提供有价值的信息，并可为林分尺度的操纵提供铺垫。
