Conference Agenda

The novel ESA Biomass satellite utilizes a P-band synthetic aperture radar sensor, whose signals can penetrate forest canopies and also interact with understory woody elements such as trunks, branches, and stems. Together with its specific observation scenario, the Biomass sensor collects these signals multiple times over the same area, allowing the mapping of vegetation height and vertical structure, which is beyond the forest cover readily derived from optical and higher-frequency radar sensors. Despite these characteristics, biomass ground data are also required to calibrate those signals and build more reliable machine learning models of forest biomass and forest height. Here, we present Geo-Quest, our free citizen-science mobile app, which includes two modules, Tree-Quest and Plot-Quest, that enable open crowdsourced ground data collection of single-tree and forest-plot attributes, including tree height, stem diameter, and species identification, all of which are necessary for estimation of aboveground biomass. Our results highlight that our app can be used to estimate tree height and stem diameter with a relative accuracy of 11% compared to measurements obtained with traditional forest inventory tools. Our first citizen science campaign, launched at the Living Planet Symposium 2025 in Vienna, engaged over 200 participants and collected more than 1100 ground observations of tree height, diameter, and species. These results show that the app is suitable for global citizen science campaigns, which can be used to provide unique open crowdsourced datasets for calibration and validation of ESA Biomass satellite products.