Vascular plant distribution in relation to topography, soils and micro-climate at five GLORIA sites in the Snowy Mountains, Australia

As part of the Global Observation Research Initiative in Alpine Environments program, the relative contribution of abiotic variables in explaining alpine vegetation was determined for five summits on a spur of Mount Clarke in the Snowy Mountains, Australia. The composition of vascular plant species and life-forms, and topography were determined, and soil nutrients and soil temperature were measured on each aspect of each summit by standardised methods. Ordinations were performed on the composition of vascular plant species and life-forms, topography, soil nutrients and soil temperature-derived variables. Abiotic variables were tested against the biotic dissimilarity matrices to determine which were best correlated with current plant composition. Summits differed in plant composition, with a decrease in the cover of shrubs, and an increase in herbs and graminoids with increasing altitude. Altitude was the main determinant of species composition, accounting for more than 80% of the variation among summits. Soil temperature variables accounted for more than 40% of the variation in composition among summits. Soils were not significantly different among summits, although certain soil variables, principally calcium, were important in predicting plant composition. Because temperature is correlated with current vegetation on these five summits, predicted increased temperatures and decreased snow cover are likely to affect future plant composition in this mountain region.