The observed global loss of biodiversity in forest ecosystems has prompted concerns on the ability of forests to function sustainably and deliver services to society also in the future. It has been suggested that diversity fosters the functioning and resilience of forest ecosystems. More diverse forests are frequently hypothesized to have higher resources use efficiency (i.e., niche complementarity) and are more likely to include highly productive tree species (i.e., selection effect). In addition, species-rich forests are suggested to buffer ecosystems against the impacts of disturbances, a proposition known as the "insurance hypothesis". Forests in Central Europe are less diverse today than in the past, as a result of century-long management practices resulting in forests relatively simple in structure and composition. In the face of increasing disturbances in Europe, it is essential to understand how diversity (a feature of forests that can be directly altered by management) acts both on the functioning and resilience of these ecosystems. Using the process-based model iLand, a factorial simulation experiment studying 128 species combinations was conducted for a temperate forest ecosystem in Central Europe. Furthermore, different disturbance regimes (including a non-disturbed scenario) with varying severity and frequency were analyzed over a gradient of tree species richness. Overall, both diversity in species and structures were found to positively affect productivity. However, relationships between tree diversity and productivity were not constant and varied, for example, over the course of forest development or selected diversity indicator. This finding highlights the importance of considering an integrated approach which accounts for extended temporal scales and different dimensions of tree diversity when aiming to fully understand how tree diversity influences ecosystem productivity. An important outcome from this study is that more diverse forests can mitigate the impacts of predicted intensifying disturbance regimes under climate change. To increase the robustness of forest ecosystem functioning, forest managers could furthermore incorporate the diversity created by disturbances into stand development.