Eco-systemic properties of Nothofagus pumilio forests affected by different livestock intensity of use in Chubut, Patagonia Argentina.
Livestock is one of the agents causing degradation in Patagonian forests, as well as in other forest areas of the world. In forest systems of Nothofagus pumilio (lenga) and adjacent meadows (mallines), a decreasing intensity pattern of cattle use was detected toward forest sectors furthest from mallines. The objective of this study was to evaluate the availability of forage in the undergrowth at the beginning of a grazing period and the stages of lenga natural regeneration in relation to the different intensities of use. The study was carried out in 3 paddocks consisting of lenga forests and adjacent mallines, in which sectors with different intensity of use were identified. The most evident changes in intensity of use were the higher biomass of shrubs in the sectors less used by cattle, and the group of herbs (mainly some exotic, tolerant to grazing and of good forage value) in the most used sectors. Lenga seedlings shorter than 0.1 m in height predominate in regeneration density. High values of lenga regeneration were registered in sectors less used by livestock, in which lower levels of damage by browsing were also registered. Lenga seedlings and saplings especially affected by cattle were those between 0.1 and 2 m in height. For livestock management, forage availability in the mallines should be considered, since its supply in forest areas is scarce and mainly composed of lenga regeneration.