Recovery of treeless subalpine vegetation in Kosciuszko National Park after the landscape-scale fire of 2003

摘要

The vegetation of fire-prone landscapes is influenced by the frequency, severity, seasonality, return interval and stochastic patterning of fire as well as the responses of its component species. An expected increase in fire frequency and severity in association with global warming may result in compositional changes within, and spatial reorganisation of, plant communities; indeed, some plant communities may even face extinction. Vegetation dominated by fire-sensitive species may be most vulnerable to change in fire frequency. A landscape-scale fire in Kosciuszko National Park in 2003 provided an opportunity to compare recovery in vegetation dominated by resprouters and fire-sensitive, obligate seeders. We hypothesised that if plant assemblages had failed to recover after 10 years in terms of species richness and cover they would have been dominated by seeder species pre-fire. After 10 years, two of the six vegetation types investigated had recovered and these were indeed dominated by resprouter species. Two groundwater-dependent vegetation types (one resprouter-dominated and one dominated by fire-sensitive species) were close to recovery. However, the other two types, non-groundwater-dependent shrublands dominated by both seeder and resprouter species, were still far from recovery at that time, with shrub cover reduced and grass cover increased. The likelihood of recovery after 10 years therefore does not appear to be solely a consequence of the regeneration strategies of the dominant species. Post-fire environmental factors (e.g. grazing, disease, climate) may be just as important as regeneration strategies in determining recovery time. Because not all vegetation had recovered after 10 years, prediction of minimum tolerable fire intervals at a landscape scale is impossible at this time. Future fire management needs to be adaptive, taking into account post-fire influences, rather than prescriptive.