Rootzone storage potential indicates the extent of rainforest resilience

Change in rainfall patterns and extended drought events can cause water stress in the rainforest which can also lead to a permanent shift of the biome into a savanna state. Rainforest in response may adapt to such environmental stress conditions to sustain ecosystem functioning or reduce functioning altogether. Previous studies related to forest resilience have mostly relied on precipitation or climatological drought as a control variable, but neither is a direct measure of forest resilience. As such, forest adaptability dynamics of the forest is poorly understood. Our research defines this adaptation capacity of vegetation as a dynamic reserve which rainforest can utilize before a potential shift to an alternate stable state, as the resilience of the rainforest. Here, we introduce the Rootzone Storage Potential (RZSP) as a direct water stress metric to understand adaptive forest resilience behaviour, using the cumulative difference between precipitation and potential evaporation (radiation-based). Since the potential evaporation used for RZSP calculation is purely radiation-based, it minimizes the effect of moisture recycling (and transport) on the system. RZSP is the potential of vegetation to optimize their resources enduring the greatest dry period. In this study, we have investigated the spatio-temporal resilience loss of the South American and African rainforest. An increasing trend of resilience loss was observed in the past few decades. Using RZSP is a useful indicator for estimating resilience dynamics and water stress characteristics of the rainforest.