Ungulate browsing induces legacy effects on woody species diversity and regeneration density in temperate forest ecosystems

Climate change is expected to intensify disturbance regimes in temperate forests, increasing the need for diverse, structurally complex, and site-adapted stands. However, high ungulate densities can impede natural regeneration by reducing sapling survival and growth, selectively suppressing palatable species, and shifting communities towards less palatable taxa, challenging measures for adapting forests to climate change. We conducted a seven-year exclosure-control study with 248 paired plots across five German federal states to quantify browsing impacts on successfully recruited regeneration (> 130 cm). We considered different forest types and site conditions and asked: (1) How does ungulate browsing affect tree recruitment success over time, in terms of species richness and abundance? (2) Does browsing alter woody species composition? (3) Can indicator species for exclosures be identified? Using hurdle models, Hill-Chao numbers, and non-metric multidimensional scaling (NMDS), we found that ungulate browsing reduced the abundance and richness of established regeneration, with these effects being moderated by site conditions. Furthermore, woody species composition diverged markedly between exclosures and controls after seven years. We identified eleven significant indicator species, with rowan ( Sorbus aucuparia L . ) showing the strongest association with ungulate exclosure. Species accumulation curves based on Hill-Chao diversity estimation methods confirmed higher woody species diversity inside exclosures. Our results demonstrate a persistent legacy effect of ungulate browsing that suppresses the recruitment of diverse, structurally complex, and climate-resilient forest regeneration. Effective browsing control - e.g., through adapted game management – is therefore essential for establishing climate-resilient mixed-forests.