Averill Colin, Waring Bonnie G, Hawkes Christine V
Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA.
Department of Ecology Evolution and Behavior, University of Minnesota, St. Paul, MN, 55455, USA.
Glob Chang Biol. 2016 May;22(5):1957-64. doi: 10.1111/gcb.13219. Epub 2016 Feb 25.
Soil moisture constrains the activity of decomposer soil microorganisms, and in turn the rate at which soil carbon returns to the atmosphere. While increases in soil moisture are generally associated with increased microbial activity, historical climate may constrain current microbial responses to moisture. However, it is not known if variation in the shape and magnitude of microbial functional responses to soil moisture can be predicted from historical climate at regional scales. To address this problem, we measured soil enzyme activity at 12 sites across a broad climate gradient spanning 442-887 mm mean annual precipitation. Measurements were made eight times over 21 months to maximize sampling during different moisture conditions. We then fit saturating functions of enzyme activity to soil moisture and extracted half saturation and maximum activity parameter values from model fits. We found that 50% of the variation in maximum activity parameters across sites could be predicted by 30-year mean annual precipitation, an indicator of historical climate, and that the effect is independent of variation in temperature, soil texture, or soil carbon concentration. Based on this finding, we suggest that variation in the shape and magnitude of soil microbial response to soil moisture due to historical climate may be remarkably predictable at regional scales, and this approach may extend to other systems. If historical contingencies on microbial activities prove to be persistent in the face of environmental change, this approach also provides a framework for incorporating historical climate effects into biogeochemical models simulating future global change scenarios.
土壤湿度限制了土壤中分解微生物的活性，进而限制了土壤碳返回大气的速率。虽然土壤湿度的增加通常与微生物活性的增加相关，但历史气候可能会限制当前微生物对湿度的反应。然而，在区域尺度上，是否可以根据历史气候预测微生物对土壤湿度的功能反应的形状和幅度的变化尚不清楚。为了解决这个问题，我们在年平均降水量为442 - 887毫米的广泛气候梯度上的12个地点测量了土壤酶活性。在21个月内进行了8次测量，以在不同湿度条件下最大限度地进行采样。然后，我们将酶活性的饱和函数拟合到土壤湿度，并从模型拟合中提取半饱和和最大活性参数值。我们发现，各地点最大活性参数50%的变化可以由30年平均年降水量预测，年平均降水量是历史气候的一个指标，并且这种影响与温度、土壤质地或土壤碳浓度的变化无关。基于这一发现，我们认为，在区域尺度上，由于历史气候导致的土壤微生物对土壤湿度的反应的形状和幅度的变化可能具有显著的可预测性，并且这种方法可能适用于其他系统。如果事实证明微生物活动的历史偶然性在面对环境变化时仍然存在，那么这种方法还提供了一个框架，可将历史气候影响纳入模拟未来全球变化情景的生物地球化学模型中。
