Competitive interactions between palatables and unpalatable grasses: Effects of selective defoliations of the palatable grasses

DISTEL, R. ; A. MORETTO

Congreso; XVIII International Grassland Congress; 1997

Selective herbivory of the palatable species appears to be a dominantmechanisms contributing to species competitive replacement ingrasslands. Selcctive herbivory of the palatable species allowsunpalatable species to realize a competitive advantage within thecommunity. To test this hypollicsis wc compare the competitiveability of the unpalatable grasses Siipa iricliotoma or S. gyneriodesin the prcscnce of nondcfoliatcd and defoliated plants of the palatablegrass S. clarazii- The three species are native to a températe semiaridgrassland of Argentina. The response variables estimated inS.triclioioma and S.f>\nerioidcs, at both plant and tiller levéis, werehigher (P < 0.05) in the prescnce of defoliated than in the presenceof undefoliated plants of S.clarazii. These results support thehypothcsis that sclectivc herbivory of the palatable species confersunpalatable species a competitive advamagcs, contributing to speciescompetitive replacement within the community.