Monitoring global tree mortality patterns and trends. Report from the VW symposium 'Crossing scales and disciplines to identify global trends of tree mortality as indicators of forest health'.

While global forest growth assessments have been carried out, no study has attempted to generate spatially explicit models of global tree mortality, which are necessary to generate a mechanistic understanding and to robustly quantify mortality at a global scale. The current initiative can build upon: (1)an increasing amount of data on forest ecosystems, including national forest inventories and monitoring, as well as an increasing number of research plot networks in all forested biomes; (2) a growing willingness of scientists and governmental agencies to openly share data; and (3) a greater availability of powerful tools for assessing and monitoring forests at broad spatial scales, such as remote-sensing products from satellites or airborne LIDAR. Despite this progress, current monitoring approaches are still incomplete in their spatial extent and data resolution is often inadequate for detecting scattered individual tree mortality and for identifying causal relationships between drivers of change in forest condition.