How soil microbial respiration responds to climate change can be constrained by historical climate. Understanding the duration of such legacy effects is key to determining how much they matter for projecting future ecosystem carbon cycling. Here, we tested whether extreme changes in rainfall could overcome constraints imposed by historical rainfall on how soil respiration responds to moisture. We predicted that larger shifts in rainfall regime would alter the magnitude or sensitivity (slope) of the respiration response to moisture compared to smaller changes in rainfall relative to historical conditions. Over 4.5 years, we imposed rain treatments ranging from extreme dry to extreme wet conditions that varied by ~400%, as well as ambient and historical mean rainfall controls. Rain treatments were applied to shortgrass or tallgrass vegetation that represented lower and higher biomass inputs, respectively, to test how shifts in soil resources might affect respiration moisture responses. We found high resistance to altered rainfall in the field, with persistent legacies indicated by no change in the respiration response to moisture among treatment and control rain treatments. The intrinsic respiration response to moisture under controlled laboratory conditions was also unaffected by field rain treatments. In response to field vegetation treatment, there was 10–30% more soil respiration in tallgrass compared to shortgrass that was paralleled by an increase in soil dissolved organic carbon, but no change in moisture sensitivity consistent with independent resource and climate effects. Soil bacteria and fungi were unchanged across all treatments and were largely generalists, suggesting high community as well as functional resistance to change. Climate legacies on soil microbial communities have the potential to modify our expectations for the rate of acclimation and adaptation to altered climate conditions.

历史气候可能会限制土壤微生物呼吸如何响应气候变化。了解此类遗留影响的持续时间对于确定它们对未来生态系统碳循环的预测至关重要。在这里，我们测试了降雨的极端变化是否可以克服历史降雨对土壤呼吸对水分的响应所施加的限制。我们预测，与历史条件相比，降雨的变化较小，而降雨状态的较大变化将改变呼吸对水分的响应的大小或敏感性（斜率）。在超过4.5年的时间里，我们实施了从极端干燥到极端潮湿的降雨处理，变化幅度约为400％，同时还控制了环境和历史平均降雨。对分别代表较低和较高生物量输入的短草或高草植被进行了雨水处理，以测试土壤资源的变化如何影响呼吸水分响应。我们发现该田对降雨变化具有很高的抵抗力，在处理和对照雨水处理之间，持续存在的遗留现象表明呼吸对水分的响应没有变化。在受控实验室条件下对水分的固有呼吸响应也不受田间雨水处理的影响。与野草相比，响应野外植被处理，高草中的土壤呼吸增加了10–30％，同时土壤可溶性有机碳增加，但对湿气的敏感性没有变化，这与独立的资源和气候效应一致。在所有处理中，土壤细菌和真菌均未改变，大部分为通才，表明存在较高的群落以及对变化的功能抵抗力。土壤微生物群落的气候遗留物有可能改变我们对气候变化条件适应和适应率的期望。