Oechel WC, Vourlitis GL, Hastings SJ, Zulueta RC, Hinzman L, Kane D
Department of Biology, San Diego State University, California 92182-4614, USA.
Nature. 2000 Aug 31;406(6799):978-81. doi: 10.1038/35023137.
Long-term sequestration of carbon in Alaskan Arctic tundra ecosystems was reversed by warming and drying of the climate in the early 1980s, resulting in substantial losses of terrestrial carbon. But recent measurements suggest that continued warming and drying has resulted in diminished CO2 efflux, and in some cases, summer CO2 sink activity. Here we compile summer CO2 flux data for two Arctic ecosystems from 1960 to the end of 1998. The results show that a return to summer sink activity has come during the warmest and driest period observed over the past four decades, and indicates a previously undemonstrated capacity for ecosystems to metabolically adjust to long-term (decadal or longer) changes in climate. The mechanisms involved are likely to include changes in nutrient cycling, physiological acclimation, and population and community reorganization. Nevertheless, despite the observed acclimation, the Arctic ecosystems studied are still annual net sources of CO2 to the atmosphere of at least 40 g C m(-2) yr(-1), due to winter release of CO2, implying that further climate change may still exacerbate CO2 emissions from Arctic ecosystems.
20世纪80年代初，气候变暖和变干逆转了阿拉斯加北极苔原生态系统长期的碳固存，导致陆地碳大量流失。但最近的测量表明，持续的变暖和变干导致二氧化碳排放减少，在某些情况下，夏季出现了二氧化碳汇活动。在此，我们汇总了1960年至1998年底两个北极生态系统的夏季二氧化碳通量数据。结果表明，在过去40年观测到的最温暖、最干燥时期，夏季出现了汇活动的恢复，这表明生态系统具有一种此前未被证实的能力，即能够在代谢上适应长期（十年或更长时间）的气候变化。其中涉及的机制可能包括养分循环的变化、生理适应以及种群和群落的重新组织。然而，尽管观察到了适应现象，但由于冬季二氧化碳的释放，所研究的北极生态系统仍然是每年向大气净排放至少40克碳每平方米的二氧化碳源，这意味着进一步的气候变化仍可能加剧北极生态系统的二氧化碳排放。
