Department of Biology, University of Pisa, CoNISMa, Via Derna 1, Pisa, Italy.
Ecology. 2019 Feb;100(2):e02578. doi: 10.1002/ecy.2578. Epub 2019 Jan 14.
Research on regime shifts has focused primarily on how changes in the intensity and duration of press disturbances precipitate natural systems into undesirable, alternative states. By contrast, the role of recurrent pulse perturbations, such as extreme climatic events, has been largely neglected, hindering our understanding of how historical processes regulate the onset of a regime shift. We performed field manipulations to evaluate whether combinations of extreme events of temperature and sediment deposition that differed in their degree of temporal clustering generated alternative states in rocky intertidal epilithic microphytobenthos (biofilms) on rocky shores. The likelihood of biofilms to shift from a vegetated to a bare state depended on the degree of temporal clustering of events, with biofilm biomass showing both states under a regime of non-clustered (60 d apart) perturbations while collapsing in the clustered (15 d apart) scenario. Our results indicate that time since the last perturbation can be an important predictor of collapse in systems exhibiting alternative states and that consideration of historical effects in studies of regime shifts may largely improve our understanding of ecosystem dynamics under climate change.
关于生态系统状态转移的研究主要集中在压力干扰的强度和持续时间如何改变，促使自然系统进入不理想的替代状态。相比之下，反复发作的脉冲干扰（如极端气候事件）的作用在很大程度上被忽视了，这阻碍了我们理解历史进程如何调节生态系统状态转移的发生。我们进行了野外操作，以评估温度和沉积物沉积的极端事件组合，这些事件在时间聚类程度上存在差异，是否会在岩石潮间带附生微藻（生物膜）中产生替代状态。生物膜从植被状态到裸露状态的转变可能性取决于事件的时间聚类程度，在非聚类（间隔 60 天）干扰的情况下，生物膜生物量表现出两种状态，而在聚类（间隔 15 天）情况下则崩溃。我们的结果表明，对于表现出替代状态的系统，上次干扰以来的时间可以成为崩溃的重要预测指标，并且在生态系统状态转移的研究中考虑历史效应可能会大大提高我们对气候变化下生态系统动态的理解。
