High density of keystone herbivore vs. conservation of natural resources: Factors affecting red deer distribution and impact on vegetation in Slowinski National Park, Poland

摘要

Rising deer densities are often in conflict with human activity. Among those conflicts there is conservation of natural resources whereas the protected areas, which are often unhunted, are known to form a hunting refuge resulting in higher deer densities than in the surrounding hunted areas. The issue is well known in many protected areas in the US, much less information on the matter is available in Europe, where protected areas are much smaller than in the other regions of the world. We studied red deer density, their distribution and pressure on vegetation in Slowinski National Park, northern Poland, whose land area is 11,000 ha and the forest area is just 6000 ha. Red deer density inside the forest area of the Park (ca. 26 ind./100 ha) was 2-3 times higher than in the surrounding hunted forest districts. Deer density in the Park had a limited influence (within a zone of 1 km) on the density of the species in the forest districts (only in one out of two districts). Despite its small size red deer densities within the Park were diversified and they were influenced by the forest site type and the distance to non-forest sites. Red deer density in the Park's forests was inversely related to the distance to food abundant agricultural areas and positively related to the distance to the cover offering ones. Though the impact on forest vegetation (in terms of its biomass) was proportional to its availability, distance to non-forest sites strongly influenced the pressure. We conclude that that lack of hunting, together with favourable food and cover condition, can increase large herbivore densities even in relatively small protected areas. Since their high densities can have a negative direct and indirect influence on biodiversity and the primary goal of protected areas is biodiversity protection, we call for more research on the issue followed by a public debate in Europe concerning potential control of large herbivore populations in protected areas.