Efecto del ramoneo bovino en renovales de Nothofagus antarctica en Chubut, Argentina, en relación con la carga ganadera y la altura de la plantas

Abstract

In northwestern Chubut province extensive cattle rearing is the main economic activity developed under ñire canopy (Nothofagus antarctica) in silvopastoral systems with a wide range of livestock stocking rates. Cattle’s browsing causes damages on ñire saplings, compromises tree regeneration and consequently woodland sustainability. In the present study, we aimed at evaluating the effects of cattle browsing on ñire tree regeneration along time, as related to stocking rate and plant height. Our study was conducted in three livestock rearing settlements in Chubut province, Argentina. Our results revealed that cattle management under low stocking rates along summer range (< 0.4 UG ha-1; livestock units ha-1) allowed saplings apex to escape browsing with a plant minimum mean height of 1.6 m. Moreover, under such conditions ñire saplings can tolerate domestic herbivory with compensatory growth to recover plant structures removed by cattle. Conversely, high stocking rate (> 0.8 UG ha-1), for an extended period, determines suppressed tree regeneration with a shrubby architecture and lower growing rates. Under such conditions livestock exclusions are needed for at least 20 years to allow regeneration recover. It is possible to make compatible livestock production with woodland persistence by managing low cattle stocking rates and monitoring saplings height.