Browsing biodiversity
KEY POINTS- Grazing and browsing impacts plan communities and vegetation structure
- Changes in vegetation structure also impacts the fauna
- Direct and indirect plant-animal ineractions shape the biodiversity
Project overview
Participants
Global goals
- 15. Life on land
Short summary
Ungulate browsing and grazing affect forests through direct and indirect plant-animal interactions, limiting forestry and but shaping and facilitating biodiversity. Thus, browsing pressures have positive and negative effects, and require intricate trade-offs in management.
Moose, roe deer, fallow deer and red deer change vegetation through browsing, while wild boar mainly affect the soil and ground vegetation through rooting. Effects on biodiversity can differ among taxonomic groups and depend on ungulate community composition, forage availability and forest characteristics. In Browsing biodiversity, we examine these relationships to inform the co-management of ungulates and forests.
We combine landscape observations with long-term exclosure experiments that exclude ungulates, including wild boar. Comparing fenced and unfenced plots allows us to investigate how ungulates affect vegetation, microclimate and other taxonomic groups. The work covers vascular plants, broadleaf regeneration, beetles and fungal communities. Ongoing analyses of fungal DNA complement completed studies of plants and beetles.
The results provide knowledge of when ungulate impacts benefit or limit different components of biodiversity. Our observational studies show that vascular plant species richness can be highest at intermediate densities of smaller deer, but these associations do not by themselves establish causation. Exclosure experiments allow us to test causal effects and show that excluding ungulates can produce denser vegetation, altered microclimates and lower species richness among ground-dwelling beetles. Browsing also reduced height growth in rowan, aspen, goat willow and oak, but site productivity and competition from conifers also affected their ability to develop into competitive trees.
Management therefore needs to consider the entire ungulate community, forage availability, site productivity and forest structure. The results provide a basis for evaluating targets for broadleaf regeneration and assessing trade-offs among components of biodiversity. This is relevant to Sweden's environmental objectives Sustainable Forests and A Rich Diversity of Plant and Animal Life, and Sustainable Development Goal 15. The work shows why reduced browsing pressure cannot be assumed to benefit all species, and may even reduce species diversity.
The project is conducted in close dialogue with its funders and wildlife management, including hunters and forest owners.
News: Browsing moose and deer affect biodiversity – can increase species richness in forests