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.

An example of Holocene vegetation stability from Camerons Lagoon, a near treeline site on the Central Plateau, Tasmania

“…By 1825, herds of up to 800 cattle were grazing on grasslands adjacent to Great Lake (Wedge 1825, in Crawford et al 1962) and by the late nineteenth century, approximately 350 000 sheep were seasonally pastured around the lakes of the Central Plateau (Shepherd 1973). Furthermore, recent studies have confirmed the long-lasting, deleterious effects of grazing in high altitude grassy ecosystems (Wimbush & Costin 1979;Leigh et al 1987;Gibson & Kirkpatrick 1989). Also, exotic pollen such as Pinus radiata, Plantago lanceolata and Taraxacum are restricted to Zone 1.…”

A critical review of the science underpinning fire management in the high altitude ecosystems of south-eastern Australia

“…Nonetheless, fifteen years after fire, an alpine herbfield was well developed, with less than 5% bare ground (Ashton and Williams, 1989;Wimbush and Costin, 1979c). The rate and extent of response varies according to disturbance history (fire and grazing) and there was 12% bare ground in herbfields some twenty years after fire (Wimbush and Costin, 1979c). Shrubs can establish in herbfields that have been burnt and/or grazed but may decline in abundance in the absence of further disturbance (Carr, 1977;Costin et al, 1959).…”

“…Shrubs can establish in herbfields that have been burnt and/or grazed but may decline in abundance in the absence of further disturbance (Carr, 1977;Costin et al, 1959). Twenty years after removal of fire and grazing, some herbfields retained a shrub cover of less than 4% (Wimbush and Costin, 1979c). Shelter and deeper soils help herbfield species establish (Costin et al, 1969).…”

An assessment of a natural wetland receiving sewage effluent

“…This may be an artifact of the dominance of these species over the more natural, but less common fen vegetation. Wimbush and Costin (1979b) have recorded that insect damage can cause the death of some plants. Factors like this must also be considered when looking at the stresses imposed on plants when the habitat is drastically altered, as by addition of sewage effluent.…”