Wolves and humans both shape patterns of deer browsing in a temperate forest ecosystem of Central Europe

Abstract

Predator–prey interactions can trigger behavioural responses in ungulates, influencing their space-use and foraging behaviour and, in turn, indirectly affecting browsing pressure. Changes in browsing pressure can affect plant recruitment and species composition, shaping forest regeneration through predator-mediated trophic cascades. Despite ecological significance, the extent to which predators indirectly affect browsing remains debated, particularly in anthropogenic landscapes where human impacts can interact with predator effects.

In this study, we investigated interactions across trophic guilds and their consequences for ungulate browsing pressure while accounting for human lethal and non-lethal activities. Human disturbance was quantified using surveys of recreational activities and hunting locations. Wolf space-use and kill-sites density were mapped from GPS telemetry; lynx and red and roe deer density was modelled from camera trap data. To monitor vegetation change, browsing pressure was assessed through landscape-scale field surveys in two years: before and after wolf establishment. All datasets were modelled to evaluate tri-trophic interactions in the Bavarian Forest National Park (Germany).

On the landscape-scale, browsing pressure was lower in the core of wolf territories and areas with higher human recreation intensity, whereas deer relative abundance was not lower in these areas. In contrast, browsing pressure was greater in areas with higher lynx activity and higher wolf kill-sites density. Comparison of browsing data before and after wolf establishment indicated that wolf recolonisation locally altered deer browsing patterns but did not affect overall browsing intensity. Overall browsing intensity increased across the park but declined within areas of high wolf utilisation density.

By analysing tri-trophic interactions incorporating human activities, this study provides field-based insights into trophic interactions in a temperate forest ecosystem. Results indicate that returning predators can resume their ecological functions within anthropogenic landscapes, with wolf effects on lower trophic levels comparable in strength to those of humans in shaping ungulate browsing patterns.