Disentangling Compound Effects of Changing Disturbance and Regeneration Across Temperate Forest Landscapes

ABSTRACT Aim Global change alters many ecological processes simultaneously. Yet, the interactive and compound effects of these changes remain difficult to quantify. Here, we addressed the question of how changes in disturbance and regeneration processes interactively alter temperate forest landscapes across three continents. Location Temperate forests of the Northern Hemisphere. Time Period 21st century. Major Taxa Studied Trees. Methods We conducted a simulation experiment to (i) disentangle the effects of interacting disturbance and regeneration processes on forest structure and composition and (ii) quantify how a changing climate modulates these interaction effects. Results Simultaneously changing disturbance and regeneration processes led to a tenfold amplification of forest change compared to changes in either disturbance or regeneration. Interaction effects were context‐dependent: At low to intermediate disturbance rates (< 1% of landscape disturbed per year), high rates of regeneration buffered against declines in forest structure. In contrast, the interactions of high disturbance and high regeneration rates amplified changes in forest composition. Climatic changes dampened structural change while amplifying compositional change. At high disturbance rates, however, the modulating effects of climate change were small, and forest change was primarily driven by disturbances. Main Conclusions 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.