Beech and Ash Dieback from Climate Stress

Beech and ash have long been pillars of temperate European forests, valued for their timber, their ecological role, and their contribution to landscape character. But both species are proving highly sensitive to the new climate regime of hotter, drier summers. Drought-stressed beeches become vulnerable to nectria, a fungal infection that causes bark cankers and crown dieback. Ash trees face a double threat: drought stress compounded by chalara (Hymenoscyphus fraxineus), an invasive fungal pathogen from East Asia that has swept across Europe since the 2000s, causing massive ash dieback with no known cure. The loss of these species has cascading effects. Beech and ash forests support distinct communities of insects, birds, fungi, mosses, and understory plants. Their disappearance changes soil chemistry, light conditions, and water cycling on the forest floor. Replacing them requires careful selection of alternative species suited to future climate conditions — a process that takes decades.