Stocking rate with sheep on the range of the Mediterranean subhumid zone. II. Effect on productivity and botanical composition ofthe herbaceous layer

Carlos Ovalle M.1, Julia Avendaño R.2, Hernán Acuña P.1 y Patricio Soto O.1

At Cauquenes, Chile, on a natural vegetational formation, called "espinal", the influence of the stocking rate over the herbaceous layer was studied, in a tríal with 1; 1.5; 2.0; 2.5; 3.0; 3.5; and 4.0 Suffolk Down ewes/hectare/year, using 10/treatment, in ayear-long continuous grazing system. Through the evolution of the botanical composition, the dry matter production, and the availabil ity and growth curves of the herbaceous layer, the reaction of this layer (pasture) to stocking rate treatments was studied. With 1.0 ewe/ha, degradatíon was observed, due to under -grazing, expressed by local ized growth and later dispertion of Carduus pycnocephalus. Over 1.0 ewe/ha, an increase of the Compositae species and a decrease of the annual Gramineaes' contribution were observed. From 1.5 ewes/ha and over, a species sequence was observed, according to their resistance to grazing. The incidence of the herbaceous layer changes over the animal productivity will be analized in a future papero

1 Estación Experimental Quilamapu (INIA), Casilla 426,ChiIlán, Chile.
2 Subestación Experimental Cauquenes (INlA), Casilla 165, Cauquenes, Chile.