Why global forest monitoring?
Recent observations of widespread tree mortality in all forested biomes indicate that forests may be threatened globally by impacts from rapidly changing climate and anthropogenic land use. However, there are no reliable global assessments of tree mortality that could confirm or refute these threats.
Isn't tree mortality already monitored?
Forest inventories and satellites monitor different components related to tree mortality (e.g. stems vs canopy loss) across different scales (from tree to continent) and these need to be unified into a single consistent picture.
How can our network make a difference?
Our network facilitates international and interdisciplinary collaborations that will combine different methods to increase spatial coverage and resolution of forest monitoring (Figure 1, below). We will produce multiple lines of evidence for large-scale mortality trends and the underlying causes of tree mortality.
Is this a new plot network?
No. We will not provide a repository for raw data, but help create and assemble derived products which can be consistently intercompared and used by many disciplines.
What are tree mortality data good for?
Changes in tree mortality over time can indicate trends in forest health. These trends can be matched against changes in environmental factors and management activities and thus provide mechanistic understanding of tree mortality.
Events of intense mortality (hotspots) can serve as platforms to identify the underlying processes leading to mortality (see Figure below). Such process information will ultimately provide mechanisms for vegetation models to better predict future responses of forests to ongoing climate and land-use change.
Click areas for details on the different methods:
Space and airborne active and passive remote sensing data will provide information at large spatial scales, and can infer mortality from changes in canopy cover, sometimes close to realtime.
Forest Inventory and Monitoring
National forest inventories, research plot networks and citizen science approaches provide trends and indicators at tree or stand level.
Large-scale vegetation models underlie IPCC assessments and are increasingly important for policy making, but suffer from limited understanding of mortality mechanisms.
Research of ecophysiological responses of trees to changes in the environment can provide mechanistic mortality relationships, improving predictive capacity.
Figure: An integrated multidisciplinary global monitoring network quantifies background tree mortality and identifies hotspots of intensive tree mortality, based on forest monitoring, satellite data, LIDAR cruises, and merged data sources including research plots and citizen science. Source: Hartmann et al. (2018).