Inventory of presumed resistant ash trees and regeneration of ash trees near resistant relatives in the context of ash dieback

European ash tree (Fraxinus excelsior) is a keystone species under heavy threat due to the exotic pathogenic fungus Hymenoscyphus fraxineus. In 2018, 144 sites centred around an ash tree considered then as resistant where established and studied in Switzerland. Every site also counts 20 other ash trees with variable health. Between 2020 and 2023, only 32 of these central resistant ash trees were visited again, and their health status reevaluated. 
This project aims at finding again all these 144 supposedly resistant ash trees, assess their health status and measure the ash tree regeneration nearby.