Does wild boar rooting affect livestock grazing areas in alpine grasslands?

Abstract

Interactions between traditional livestock management practices and wildlife activities are important in the conservation of many mountain ecosystems including the summer rangelands in the Spanish Central Pyrenees, where rooting by wild boar (Sus scrofa) is a large disturbance that can reduce the amount of area available to grazing livestock. This study explored the likely impact of wild boar rooting on Pyrenean grasslands. It quantified the extent of wild boar rooting in livestock grazing areas and determined whether wild boars selected or avoided areas depending on the type of livestock and stocking rates. Wild boar rooting affected 16% of livestock grazing area and occurred in sites that were grazed by cattle, rather than by sheep. In addition, a preference for areas that had intermediate stocking rates was found. The relationship between the increase in the number of wild boars and trends in livestock management suggests that the extent of wild boar rooting will increase especially in cattle grazing areas, and therefore, the area available for cattle grazing in Pyrenean mountain rangelands would decrease significantly.

Assessment of wild boar rooting on ecological and pastoral values of alpine pyrenean grasslands

“…Therefore, wild boars may need to look actively for high-nutrient content foods, which they would more easily find in these highly-valuable pastoral areas, as plants in highly grazed areas are suggested to have higher nutrient content, both above and belowground (Bryant et al, 1983;Gibson, 2009). However, this feeding selection for nutrient-rich food items may in part not fit previous results showing a preference of wild boars to root in livestock grazing areas that withstand a moderate stocking pressure instead of areas with high stocking pressure (Bueno et al, 2010). Assuming the most grazed areas i.e.…”

“…For ecological values, despite finding a clear trend of ecological degra-dation due to disturbances, areas of high ecological value remained unaffected. Therefore, notwithstanding the vast extent of wild boar rooting (321.5 ha in the study area; Bueno et al, 2009) and the evident affection to grazing in this protected area (16.2 % of livestock grazing area affected by wild boar rooting; Bueno et al, 2010), the impact of wild boar may be considered as moderate in terms of current conservation value. Nevertheless, the potentially increasing trend of this disturbance (Bueno et al, 2010) may lead to some concerns regarding the preservation of these habitats in the near future.…”

“…This might be related to the origin and dynamics of these grasslands in the Middle Ages, when lands were gained to the forest for grazing activities (Fillat et al, 2008;Bueno et al, 2010). The floristic composition of those communities might have changed from stress-tolerant species in the early stages, to grazing-tolerant species spread or even brought along from lowland areas by livestock (Austrheim et al, 1999).…”

“…clearly outside disturbances) and calculating the overall accuracy of the map through a confusion matrix (Congalton & Green, 2009). The overall accuracy of the map was 90.6 % of correct classification (Bueno et al, 2010).…”

“…These disturbances (hereafter 'rooting') affect directly some ecosystem elements, such as soils (Lacki & Lancia, 1983;Bueno et al, unpublished-b) and vegetation (Bratton, 1975;Bueno et al, unpublished-a), and may indirectly alter some ecosystem processes such as nutrient cycling and species turnover (Kotanen, 1995;Bueno et al, unpublished-b). Rooting can be worrisome in some places, as it may affect habitats particularly sensitive to soil disturbances such as Pyrenean alpine grasslands (García-González, 2008) with indirect consequences to traditional grazing activities that preserve the system and hold local economies (Bueno et al, 2010). Therefore, evaluating the direct and main indirect implications of these disturbances is basic to guide adequate management actions and understand future consequences (Carpenter, 2002).…”