The ecological consequences of future droughts are difficult to predict due to a limited understanding of the nonlinear responses of plants to increasing drought intensity, which can change abruptly when critical thresholds of drought intensity are crossed. Drought responses are composed of resistance and postdrought recovery. Although it is well established that higher drought intensity increases the impact and, thus, reduces plant resistance, less is known about how drought intensity affects recovery and how resistance and recovery are related. In this study, we tested the hypothesis that resistance, recovery, and their relationship change abruptly upon crossing critical thresholds of drought intensity.
Drought is considered the most widespread climate extreme affecting ecosystem productivity and the terrestrial carbon cycle (Reichstein et al., 2013; Sippel et al., 2018). Future drought regimes are likely to intensify with the projected increase in climate variability (Büntgen et al., 2021; Satoh et al., 2022; Spinoni et al., 2018), but the ecological implications remain uncertain due to a lack of understanding of how drought intensity drives ecological responses (Felton et al., 2021; Vicente-Serrano et al., 2020). Ecological responses to a pulsed disturbance, such as drought, can be described by a system's resistance, that is, the ability of an ecosystem to withstand drought, and its recovery after disturbance (Ingrisch & Bahn, 2018). The latter ultimately defines whether a drought's impact can be overcome and, thus, whether drought effects are transient or persistent (Hillebrand & Kunze, 2020; Jentsch & White, 2019). Therefore, an understanding of the characteristics of an ecological response to disturbance requires a joint consideration of resistance and recovery