Ecohydrological decoupling under changing disturbances and climate

Terrestrial disturbances are increasing in frequency and severity, perturbing the hydrologic cycle by altering vegetation-mediated water use and microclimate. Here, we synthesize the literature on post-disturbance ecohydrological coupling, including the mechanistic relationship between vegetation and streamflow, under changing disturbance regimes, atmospheric CO2, and climate. Disturbance can cause decoupling between transpiration and streamflow by altering the connectivity, size, availability, and spatial distribution of their source pools. Successional trajectories influence the dynamics of source water partitioning. Changing climate and disturbance regimes can alter succession and prolong decoupling. Increasing rates, severity, and spread of disturbances along with warming could promote greater decoupling globally. From this review emerges a framework of testable hypotheses that identify the critical processes regulating ecohydrological coupling and provide a roadmap for future research. Accurate prediction of post-disturbance coupling requires understanding the degree of hydraulic connectivity between source water pools and their response to succession under changing disturbance and climate regimes.