MORPHOLOGICAL ANALYSIS OF HERBACEOUS COMMUNITIES UNDER DIFFERENT GRAZING REGIMES

A methodology for the morphological analysis of herbaceous communities is presented, together with an example of its application in montane grasslands in the province of Cordoba (Argentina) subject to grazing and burning. The method, based on multivariate ordination and classification techniques, enabled the detection of morphological changes at three levels in response to disturbance: (a) characterization of the spatial structure of the vegetation; (b) identification of morphological plant groups; and (c) quantification of morphological shifts among different individuals of a single species. The architecture of the vegetation changed toward a progressive miniaturization of photosynthetic structures and concentration of biomass close to the ground, as disturbance intensity increased. Six morphological plant groups (modes of response) showing different behaviour in relation to competition for light and pressure from large herbivores were identified. Some species, highly preferred by ungulate grazers, showed high morphological variability among morphs growing in different grazing situations, whereas some others were morphologically uniform.