Abstract

YEZZI, Alejandra L; NEBBIA, Ana J  and  ZALBA, Sergio M. Psamophilous grassland fragmentation due to pine plantations: effects on species richness and plant composition. Ecol. austral [online]. 2018, vol.28, n.1, pp.133-144. ISSN 1667-782X.

The coastal dunes of the Pampa Austral are comparatively better preserved than the rest of the Pampas grasslands, but they are also threatened by anthropogenic intervention. Plantations of exotic species reduce the area of psamophilous grasslands, fragmenting the ecosystem and limiting the original native vegetation to relic areas. The objectives of this study were to evaluate the effects of grassland fragmentation on plant communities and to identify parameters that highlight the impacts of this process with greater clarity. Community attributes were evaluated in grassland fragments of different size (0.05 to 2.5 ha) surrounded by a forest matrix and compared to control areas of continuous grasslands of equivalent area. A significant positive relationship was found between the area of the study units and the richness of native and exotic plants, and total plant diversity. The smaller fragments presented greater exotic species richness and less native species richness than the continuous grasslands. Ambrosia tenuifolia, a native species associated with disturbances, and the exotic Senecio madagascariensis, were found among the predominant species in smaller fragments. In the larger fragments predominated the native Cyperus reflexus and Hydrocotyle bonariensis, all characteristic of humid habitats. Grasses and other native plants, such as Panicum urvilleanum and Margyricarpus pinnatus, predominated in the continuous grasslands. We found species composition to be a more sensible indicator of the alterations associated with the fragmentation of grasslands when compared with changes in species richness and diversity, and it also allows to hypothesize about particular factors that could explain the presence or abundance of certain taxa. Variations in the distribution of certain taxonomic groups can guide research aimed at evaluating the effect of fragmentation on different ecological processes.

Keywords : Habitat destruction; Pampa biome; Coastal dunes; Invasive alien plants.

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