1. Anthropogenic global change compromises forest resilience, with profound impacts to ecosystem functions and services. This synthesis paper re flects on the current understanding of forest resilience and potential tipping points under environmental change and explores challenges to assessing responses using experiments, observations and models.

2. Forests are changing over a wide range of spatio-temporal scales, but it is often unclear whether these changes reduce resilience o r represent a tipping point. Tipping points may arise from interac- tions across scales, as processes such as climate change, land-use change, invasive species or defor- estation gradually erode resilience and increase vulnerability to extreme events. Studies covering interacti ons across different spatio-temporal scales are needed to further our understanding.

3. Combinations of experiments, observations and process-based models could improve our ability to project forest resilience and tipping points under global change. We discuss uncertainties in changing CO 2 concentration and quantifying tree mortality as examples.

4. Synthesis. As forests change at various scales, it is increasingly important to understand whether and how such changes lead to reduced resilience and potential tipping points. Under- standing the mechanisms underlying forest resilience and tipping points would help in assessing risks to ecosystems and presents opportunities for ecosystem restoration and sustainable forest management.