Forest ecosystems cover about 31% of the Earth’s land surface and strongly impact climate, global biogeochemical cycles, biodiversity and human welfare. Individual tree as well as whole forest mortality is predicted to increase due to climatic changes as well as anthropogenic impact. However, whether these trends reflect an overall decrease in forest health at the global scale is currently unknown and we lack information essential for understanding forest decline and for predicting future forest condition.

Existing forest monitoring approaches are spatially limited (e.g. ICP Forests covering Europe) or use data with an inadequate resolution for detecting individual tree mortality (e.g. LANDSAT). Such data exist but are spread across many different depositories and disciplines (field monitoring networks, forest inventories, remote sensing). A shared and openly accessible depository within the context of a monitoring network would facilitate a horizontal (across disciplines) and vertical (across spatial scales) information transfer and the rapid detection and interpretation of changes in forest condition and future development of global forest ecosystems. Recent tree-mortality workshops in Jena and Hannover have shown that addressing the geographical extent of forest die-off at the global scale and the vulnerability of individual biomes to increasing temperatures are of paramount importance. Therefore, a global monitoring network on forest conditions, involving forest inventories, internationally available plot networks and remote sensing (space- and airborne) was founded at the Hannover workshop (www.tree-mortality.net). The network also promotes new data acquisition tools, such as a tree mortality smartphone app, and actively seeks interaction between different groups of stakeholders (e.g., science, the general public, politics and government and NGOs among others).

The purpose of this session is to promote and actively seek interdisciplinary collaboration with the international global monitoring network. We encourage submissions from all disciplines that can provide information on current state of forest condition (in particular tree mortality) like ecophysiological monitoring, forest inventories, plot networks and remote sensing. We also invite contributions that encourage citizen science, in particular approaches that promote data acquisition via digital tools like smartphone apps. Submissions may cover a wide range of spatial scales spanning from local (forest stand) to global.