Mapping Fractional Tree Mortality and Tree Cover at Global Scale Using Sentinel-1 and 2

In the wake of extreme heat and drought events, excess tree mortality is increasing globally. While forest inventories provide valuable data for geolocating tree mortality, they are sparse and do not identify individual tree mortality. Aerial data captured by drones and airplanes provide precise centimeter-scale imagery that can be used to map individual tree mortality and fractional forest cover. The deadtrees.earth platform provides a comprehensive archive of annotated high-resolution orthoimages captured around the globe for different ecosystems and biomes. By using the imagery from deadtrees.earth, it is possible to detect and predict individual tree mortality and forest cover using high-resolution RGB orthoimagery at the regional scale. Here we present a methodology that allows generating global maps of tree mortality and fractional cover using satellite imagery from high-resolution aerial  orthoimagery. 
The Sentinel-2 satellite fleet, equipped with the MultiSpectral Instrument (MSI), covers the entire Earth within five days at spatial resolutions ranging from 10 m to 60 m. The Sentinel-1 satellite fleet offers global temporally continuous radar coverage that penetrates clouds.  Tree mortality and forest cover reference data in diverse ecosystems is obtained by using multiple segmentation models on the globally distributed high-resolution aerial orthoimagery database deadtrees.earth. Spatio-temporal signatures of Sentinel 1/2 satellites are then translated into forest properties by using novel Transformer architectures. In this study, we highlight how to map the share of standing deadwood and forest cover at 10 m resolution annually, generalizing to all ecosystems. This will enable us to map tree mortality and forest cover at a global scale at a new level of precision.