Effects of long-term enhanced game population density on soil physical, chemical, and microbiological properties

Forests are critically influenced by game animals since the browsing and peeling by these animals has a detrimental effect on forests by affecting a broad range of processes in forest ecosystems. Further, plants that are browsed by herbivorous game animals show stress reactions which can lead to a change in plant species composition and in belowground interactions between roots and soil microorganisms. On the other hand, a high game population density leads to high nutrient and carbon (C) inputs via excrement and, in case of feeding, via fodder inputs. These inputs can have positive effects on plant nutrition and growth as well as soil organic C build-up. While previous studies have focused on various topics related to the effects of game animals on forest ecosystems, an overarching understanding of soil-plant-wildlife interactions and feedback reactions is still missing. In this study, we aim at tackling this short-coming and elucidating the effect of long-term enhanced game population density on soil physical, chemical, and microbial properties. The study site includes different forest types located in the vicinity of Vienna, Austria, and consists of a fenced area with high game animal population density and a directly adjacent, open forest area with lower animal density, serving as a control. Soil samples were taken from three depths (0-10 cm, 10-20 cm, 20-50 cm) from ten sub-sites differing in plant species composition and underbrush density. In the laboratory, we analyzed soil density, particle size distribution, pH, electric conductivity, total C and N, microbial biomass C and N, plant-available nutrients, and root density to study the effect of a high density of game animals (wild boars, deer) in the study area. The results gained in this study will serve as a scientific basis for a subsequent, long-term research and monitoring strategy. Here, we present results from the first sampling campaign and discuss implications of environmental impacts of wildlife animals on a larger scale.