High ungulate densities can have significant effects on forest vegetation, leading to shifts in habitat structure and composition [1]. Their browsing behaviour can particularly impact natural regeneration, biomass development, and plant diversity, reducing the share of certain plant species [2]. Moreover, large ungulate populations can affect higher trophic levels in forest ecosystems [3]. In insect food webs, e.g., host-parasitoid interactions can be indirectly influenced by ungulate browsing. These cascading effects can modify the natural regulation of phytophagous insects by potentially beneficial parasitoid and predatory insects, thus, altering ecosystem stability [4].

The WiWaldI project analyses the consequences of ungulate browsing for insect food webs in forest ecosystems. The study focuses on trophic interactions between phytophagous, parasitoid and predatory insects. Insect habitats and communities will be identified at selected locations in Germany with different climatic, geological and forestry characteristics. The browsing effects will be determined by comparing unfenced and fenced plots. To analyse the insect communities, malaise traps and window flight traps were installed. Beating sheets were used on tree saplings of palatable species to identify insect communities specific to shrubs and tree species, as well as host plants.

The findings should contribute to the understanding of the interactions between ungulate populations and ecosystem functions in forests. Additionally, the study can provide habitat indicators for potentially beneficial insects, which could lead to practical recommendations for the biological control of phytophagous insects and the development of resilient and adaptable forests.

[1] Côté, S. D.; Beguin, J.; de Bellefeuille, S.; Champagne, E.; Thiffault, N.; Tremblay, J.-P. (2014): Structuring effects of deer in boreal forest ecosystems. Advances in Ecology, 1-10.
[2] Vor, T.; Ammer, C. (2021): Das BioWild-Projekt. Vegetationsentwicklung unter Wildeinfluss. Ökojagd 4, 19-24.
[3] Schulze, E. D.; Bouriaud, O.; Wäldchen, J. et al. (2014): Ungulate browsing causes species loss in deciduous forests independent of community dynamics and silvicultural management in Central and Southeastern Europe. Annals of Forest Research 57 (2), 267-288.
[4] Allombert, S.; Stockton, S.; Martin, J.-L. (2005): A natural experiment on the impact of overabundant deer on forest invertebrates. Conservation Biology 19 (6), 1917-1929.