van Groenigen Kees-Jan, Six Johan, Hungate Bruce A, de Graaff Marie-Anne, van Breemen Nico, van Kessel Chris
Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616, USA.
Proc Natl Acad Sci U S A. 2006 Apr 25;103(17):6571-4. doi: 10.1073/pnas.0509038103. Epub 2006 Apr 13.
Rising levels of atmospheric CO2 are thought to increase C sinks in terrestrial ecosystems. The potential of these sinks to mitigate CO2 emissions, however, may be constrained by nutrients. By using metaanalysis, we found that elevated CO2 only causes accumulation of soil C when N is added at rates well above typical atmospheric N inputs. Similarly, elevated CO2 only enhances N2 fixation, the major natural process providing soil N input, when other nutrients (e.g., phosphorus, molybdenum, and potassium) are added. Hence, soil C sequestration under elevated CO2 is constrained both directly by N availability and indirectly by nutrients needed to support N2 fixation.
大气中二氧化碳水平的上升被认为会增加陆地生态系统中的碳汇。然而，这些碳汇缓解二氧化碳排放的潜力可能受到养分的限制。通过荟萃分析，我们发现只有当氮的添加量远高于典型的大气氮输入量时，二氧化碳浓度升高才会导致土壤碳的积累。同样，只有当添加其他养分（如磷、钼和钾）时，二氧化碳浓度升高才会增强固氮作用，即提供土壤氮输入的主要自然过程。因此，二氧化碳浓度升高条件下的土壤碳固存直接受到氮有效性的限制，间接受到支持固氮作用所需养分的限制。
