Effects of the silvopastoralism with sheep in the regeneration and survival of Abies hickelii (Flous and Gaussen)

Abstract

The natural regeneration of temperate forests is frequently depleted by anthropogenic practices such as overgrazing, excessive logging, and forest fires. In Mexico, biodiversity conservation is an important objective, although many small farmers who depend on native forest vegetation for extensive grazing to raise their herds. The objective of this work was to characterize the vegetation of the A. hickelii understory in Pico de Orizaba National Park and to evaluate the impact of sheep grazing on the regeneration and survival of A. hickelii seedlings on a temperate forest. Two experimental sites were established, one was used for natural regeneration and the other for transplanting of A. hickelii. Each site was divided into six paddocks, three for sheep grazing (a flock of nine lambs on rotational grazing for 134 days) and three ungrazed paddocks. Three cycles of grazing were carried out and in each of them the florist composition, the vegetation cover, the height of the seedlings, the number of terminal buds nibbled by the sheep, the number of dead trees and the body weight of the animals were measured. The impact of grazing on vegetation cover was significant (P < 0.05) in both sampling sites, going from 80 to 30% in the natural regeneration and transplanting of A. hickelii seedlings, respectively. There was a decrease in the number of herbaceous species present because of grazing in both experimental sites. However, the survival of A. hickelii seedlings was higher than 80% in both sampling sites and the dead trees did not show any physical damage due to the presence of the sheep herd. The lambs had daily weight gains of 63 g animal⁻¹ d⁻¹. In conclusion, the negative effects of sheep grazing on A. hickelii seedlings are low; therefore, it is feasible to promote silvopastoral systems with sheep in the temperate forests of A. hickelii.