Disentangling compound effects of changing disturbance and regeneration across temperate forest landscapes

Global change alters many ecological processes simultaneously. Yet, the interactive and compound effects of these changes remain difficult to quantify. Here, we conducted an extensive experiment in silico to address the question of how changes in disturbance and regeneration interactively alter temperate forest landscapes across three continents. Interaction effects between changing disturbance and regeneration processes amplified ecosystem change by an order of magnitude compared to the effects of changes in individual drivers. Interaction effects were context-dependent. At low to intermediate disturbance rates (<1 % yr^-1^), high rates of regeneration buffered effects on forest structure. In contrast, the interaction of high disturbance and regeneration rates amplified changes in forest composition. We conclude that the consequences of changing disturbance and regeneration need to be assessed jointly to understand their outcomes. Our findings highlight the importance of interaction effects of simultaneously changing ecological processes in shaping the future of forest ecosystems.

Methods
We used the individual-based forest landscape and disturbance model iLand to investigate the response of three protected temperate forest landscapes on three continents to changes in disturbance and regeneration processes under climate change. The simulation outputs were processed in R to derive the final datasets for analysis.