Resumo

QUIROGA, Emiliano; BLANCO, Lisandro  e  ORIONTE, Enrique. Testing rehabilitation strategies for arid rangelands. Ecol. austral [online]. 2009, vol.19, n.2, pp.107-117. ISSN 1667-782X.

Overgrazing by domestic cattle has caused loss of plant diversity and primary productivity in rangelands of the Arid Chaco (Argentina). The objective of our study was to evaluate a number of rehabilitation strategies that might increase the density of forage grasses in an overgrazed rangeland in this region. Based on the hypothesis that soil compaction, lack of seeds and litter cover constrain plant establishment we performed a field factorial experiment, that combined soil pitting, seed addition and the combined effect of competition release and litter addition. During four years, we evaluated seedling and plant density of added grasses and all forage grasses. Seed addition was the only factor that increased seedling and plant density, with Pappophorum spp. and P. philippianum accounting for the main variation in seedling and plant density, respectively. During the third year (a dry year), there was 70-80% decrease in plant density in all treatments, although the differences due to the addition of seeds was still apparent. Our results suggest that, in addition to adverse climatic conditions, the lack of seeds in the soil bank restricts the recovery of overgrazed rangelands in the Arid Chaco. Pappophorum philippianum seems to be a promising species for the rehabilitation of these rangelands.

Palavras-chave : Forage grasses; Plant density; Vegetation recovery; Degraded areas; Arid Chaco.

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