Perennial grasses traits as functional markers of grazing intensity in basaltic grasslands of Uruguay

Abstract

Natural grasslands in the basaltic region of Uruguay are threatened by\nan increase in stocking rates and changes in land use. To assess the\neffect of grazing intensification, plant functional types are proposed\nas simple tools to aid the monitoring and management of vegetation. In\nthe present study we evaluated the effect of stocking rate increase at\ncommunity level taking into account plant traits of 23 dominant\nperennial grass species. In order to identify plant functional types,\nwe determined the grazing response in an experiment with two wethers\nstocking rates (0.78 and 1.56 livestock units ha-1) quantifying species\ncover and traits values. Leaf dry matter content (LDMC) and specific\nleaf area (SLA) were the traits that best described the perennial\ngrasses response to the stocking rate increase and therefore are\nsuggested to be used as functional markers. Three functional types were\nidentified. Low stocking rates were related to functional type A (tall,\nwarm season species with low SLA and high LDMC and functional type B\n(tall, cool-season species, with intermediate levels of leaf traits).\nOn the other hand, high stocking rate encouraged functional type C\n(prostrate, warm season species, with high SLA and low LDMC). The\nclassification of a highly diverse community into three functional\ntypes and the selection of traits as functional markers candidates is\nan innovative approach to develop simple and general methods to\ndiagnosis the state of basaltic grasslands in Uruguay and to advise on\nits management.