Biogeochemical and ecological feedbacks in grassland responses to warming
Biogeochemical and ecological feedbacks in grassland responses to warming
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DOI：
10.1038/nclimate1486
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发表时间：
2012-06
影响因子：
30.7
通讯作者：
Zhuoting Wu;P. Dijkstra;G. Koch;B. Hungate
中科院分区：
文献类型：
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作者：
Zhuoting Wu;P. Dijkstra;G. Koch;B. Hungate
植物生长通常对实验模拟的气候变化反应迅速。反馈可以调节初始响应，但是当它们在长时间尺度上运行时，这些反馈很难被检测到。我们将完整的植物-土壤中生态系统沿海拔梯度向下移植，使其暴露在更温暖的气候中，并使用收集器和截流器模拟降水变化。研究表明，气候变暖最初增加了4个草地生态系统的地上净初级生产力，但这种响应在9年内逐渐减弱。气候变暖改变了植物群落，导致典型温暖环境物种的入侵和原生环境物种的损失——这与植物生产力响应的下降有关。增温刺激了土壤氮素周转，这抑制了但没有逆转生产力响应的时间下降。变暖还增加了N的损失，这可能削弱了预期的生物地球化学反馈，即变暖刺激N矿化和植物生长。研究结果表明，短期实验不足以反映生态系统对环境变化的响应及其通过生物地球化学和生态反馈调节的时间变异性和趋势。
Plant growth often responds rapidly to experimentally simulated climate change,. Feedbacks can modulate the initial responses, but these feedbacks are difficult to detect when they operate on long timescales. We transplanted intact plant–soil mesocosms down an elevation gradient to expose them to a warmer climate and used collectors and interceptors to simulate changes in precipitation. Here, we show that warming initially increased aboveground net primary productivity in four grassland ecosystems, but the response diminished progressively over nine years. Warming altered the plant community, causing encroachment by species typical of warmer environments and loss of species from the native environment—trends associated with the declining response of plant productivity. Warming stimulated soil nitrogen turnover, which dampened but did not reverse the temporal decline in the productivity response. Warming also enhanced N losses, which may have weakened the expected biogeochemical feedback where warming stimulates N mineralization and plant growth,,. Our results, describing the responses of four ecosystems to nearly a decade of simulated climate change, indicate that short-term experiments are insufficient to capture the temporal variability and trend of ecosystem responses to environmental change and their modulation through biogeochemical and ecological feedbacks.