Relationships between geomorphology and vegetation patterns in subantarctic Andean tundra of Tierra del Fuego

Abstract

We analysed vegetation patterns in relation to geomorphology in subantarctic Andean tundra (Tierra del Fuego, southern Argentina). Habitat variation associated with geomorphology played a major role in structuring vegetation. On coarse-grained debris of talus cones, the vegetation is dominated by the epilithic fruticose lichen Neuropogon aurantiaco-ater, while vascular-plant cover is very low because of insufficient space available for seedling establishment, water shortage and, presumably, low nutrient status. Turf-banked lobes on moderately inclined slopes subject to downslope creep are characterised by vascular species forming large cushions (especially Azorella lycopodioides) which provide suitable microhabitats for several plants. Steep morainic slopes are extremely poor in species and have Marsippospermum reichei and Nardophyllum bryoides as characteristic species. The latter appears well adapted to withstand mechanical damage owing to its clonal creeping growth form. Screes represent intermediate habitats where the ecotonal species Bolax gummifera colonises debris and/or basal rock and may enhance the establishment of vascular species.