Relationship Between Soil Nitrogen and Floristic Variation in Late Snow Areas of the Koscinsko Alpine Region [Australia].

Abstract

We studied soil and vegetation patterns of two late snow areas in the Kosciusko alpine region of New South Wales, Australia. Marked floristic differences were found between the lower, central and upper regions of each area. The distributions of six selected species, and the spatial variation in total vegetation cover, were related to the spatial variation in total and exchangeable soil nitrogen concentrations. To test whether variations in soil nitrogen were controlling the spatial separation of late snow area plant species six selected species were subsequently grown at 12-15°C, over a range of increasing nitrogen concentrations. Five of the six selected species (Luzula oldfieldii subsp. dura, Epilobium tasmanicum, Plantago glacialis, Luzula acutifolia subsp. nana and Ranunculus niphophilus) showed similar responses to increasing nitrogen levels, both in terms of relative dry weight production and shoot nitrogen concentrations. Only in one species (Colobanthus nivicola) did responses suggest that it may have been more suited to growth on nitrogen-deficient soils. We concluded, however, that variations in nitrogen availability alone are not responsible for the floristic variation in late snow areas. Possible factors responsible for the variation in floristic composition of the late snow areas are discussed.