Resumen

FRANZESE, Jorgelina  y  GHERMANDI, Luciana. Rumex acetosella L. (Polygonaceae) invasion degree and its relationship with the vegetation attributes of two grassland communities in NW Patagonia. Ecol. austral [online]. 2012, vol.22, n.2, pp.101-111. ISSN 1667-782X.

Rumex acetosella is an exotic perennial herb that invades grassland gaps (i.e., area between tussock grasses) at NW Patagonia. The aim of this study was to estimate the degree of invasion of R. acetosella and to relate cover fluctuations to gap vegetation characteristics in communities dominated by Pappostipa speciosa (ex Stipa speciosa) and communities dominated by Festuca pallescens. We randomly selected ten gaps at each community type and estimated R. acetosella seed production (2008, 2010, and 2011) and cover of all species (2008-2010). We compared three seasons with different meteorological conditions. Rumex acetosella was present in 98% of the studied gaps and was the dominant species. Regeneration of R. acetosella was originated from resprouting rhizomes, despite the abundant seed production (2660-6900 seeds/m²). Rumex acetosella showed greater invasion in gaps from P. speciosa communities that in those from communities dominated by F. pallescens. Lower richness in the former, may limit interspecific interactions, which could benefit R. acetosella. Annual herbs were particularly affected by drought and by the increase in R. acetosella cover. The marked fluctuations in the dominant exotic species cover and in the meteorological conditions produced notable changes on the attributes of gap vegetation.

Palabras clave : Gaps; Festuca pallescens; Pappostipa speciosa; Exotic perennial herb; Semi-arid grasslands.

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