Trends in Vegetation at Kosciusko. III. Alpine Range Transects, 1959-1978

Abstract

Measurements of overlapping cover of plant species on permanent transects between 1959 and 1978 in the alpine tract at two sites near Kosciusko and Gungartan generally confirm an earlier hypothesis that the cover at Kosciusko, after 15 years' protection from grazing and burning (i.e, by 1959), had attained a degree of equilibrium. A long-term cycle of first decrease and then increase was measured in the cover of the dominant snowgrasses (Poa) and a few other species. Small colonizing species (notably Neopaxia australasica of the short alpine herbfield) increased and then decreased; temporarily spreading onto the dead snowgrasses. Very little bare soil was exposed at any time at Kosciusko; however, the cover of most species fluctuated in the short term in response to dry summers and late-lying snow.

At Gungartan, where grazing continued until 1958, the cover of species underwent similar fluctuations but, whilst not reaching the levels measured at Kosciusko, it showed a strong upward trend. Neopaxia australasica, which had occupied many slopes below snowdrift areas, was largely replaced by snowgrasses and tall hygrophilous sedges. The naturalized sorrel (Rumex acetosella), after spreading onto some of the Neopaxia sites and bare soil, was also largely replaced by taller species. Despite a marked decrease in the amount of bare soil, some of the most severely eroded areas at Gungartan were still unvegetated after 20 years' protection. Observation of nearby ground-water areas confirmed-ds indicated by a limited number of measurements at Gungartan, i.e. that hygrophilous sedges recovering frorn the effects of grazing were blocking small streams and that Sphagnum moss and associated shrubs were beginning to spread.

The above-mentioned changes in vegetation were evaluated in terms of catchment protection, water yield and nature conservation and recreation. Near-optimal conditions for these uses were maintained at Kosciusko. At Gungartan recovery to the conditions of the Kosciusko vegetation was restricted to the least-disturbed sites.