INVESTIGADORES
PAZOS gustavo Enrique
congresos y reuniones científicas
Título:
Ecological strategies and response to grazing: spatial patterns of perennial grasses in the Patagonian Monte, Argentina
Autor/es:
PAZOS, G. E.; BISIGATO, A. J.; ARES, J. O.; BERTILLER, M. B.
Lugar:
Mérida, México
Reunión:
Congreso; ESA-México Meeting: Ecology in an Era of Globalization; 2006
Resumen:
Plant ecological strategies play a key role in the species response to stress and disturbance. The trade-off between allocation of photosynthetic resources to growth (acquisitive species) and defences (conservative species) is an important attribute related to plant responses to grazing. Also, the analysis of this trade-off is useful to interpret and predict changes in plant communities under grazing disturbance. In this work, we analysed the density and spatial distribution of three dominant perennial grass species in relation to shrub patches (“fertility islands”) in areas with different sheep-grazing pressure of the Patagonian Monte. Species were sorted along an axis of strategy variation (acquisitive vs. conservative) according to ten traits that included morphological (leaf mass/area ratio, leaf length, plant height, and seed length, among others), chemical (nitrogen and lignin concentration in green leaves), and reproductive (monoecy vs. dioecy) traits. Poa ligularis was the most acquisitive species, Stipa speciosa was the most conservative one, and S. tenuis occupied an intermediate position. A reduction in plant density in highly grazed areas was observed only for S. speciosa. In lightly grazed areas, P. ligularis and S. speciosa were strongly associated with shrub patches while S. tenuis was dissociated from them. In highly grazed areas, P. ligularis showed lower intensity of association with shrub patches than in lightly grazed ones, while the spatial pattern of S. speciosa did not vary. Stipa tenuis was more associated with shrub patches in highly than in lightly grazed areas. These results show that patterns of grazing response are related to the ecological strategy of each species.