Effects of selective defoliation on the competitive interaction between palatable and unpalatable grasses native to a temperate semi-arid grasslaand of Argentina

MORETTO, A. ; R. DISTEL

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1999 vol. 42 p. 167 - 175

0140-1963

Floristic changes induced by grazing frequently involve the replacement of palatable grasses by unpalatable grasses in native grasslands. It is hypothesized that selective defoliation of palatable species allows unpalatable species to realize a competitive advantage. To test this hypothesis, we quantified growth of two unpalatable grasses (Stipa trichotomaandS. gyneriodes) in the presence of non-defoliated and defoliated plants of the palatable grassS. claraziiunder field and greenhouse conditions. Basal area, end-of-season aerial biomass, seed production, total green blade length per tiller, tiller recruitment and tiller dry mass ofS. trichotomaandS. gynerioideswere higher (p(0)05) in the presence of defoliated plants ofS. claraziithan in the presence of non-defoliated plants of the same species. These results support the hypothesis that selective defoliation of palatable species confers a competitive advantage to unpalatable species, which could ultimately lead to replacement in grasslands.