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Effects of fire on alpine plant communities in Tasmania.

Fire in alpine plant communities in Tasmania has a long term effect on the floristics, diversity and productivity of the community. Alpine plants in Tasmania are adapted to survive in very harsh conditions, usually dry and potentially very hot in summer and buried in snow for months over winter, blasted with freezing icy wind and rain at any time of the year and baked in the hot alpine sun during the hotter seasons. Fire is not a frequent visitor to these communities and many alpine plants are not resistant to the immediate impacts of fire, have no post-fire regeneration or recovery strategies and have limited dispersal range to recolonise burnt areas. Alpine communities affected by wildfire take many decades and longer to recover. Alpine soils depths are generally shallow and post fire erosion due to fire induced soil disturbance and exposure to environmental elements can further limit community recovery. Alpine plants have been measured as only growing 1mm per year, leading to very slow recovery rates of new vegetation. Fire scars left in vegetation from wildfire in alpine communities remain obvious for significant periods of time, exacerbated by the folorn vision of dead alpine trees, mostly Athrotaxis cupressoides, an endemic Tasmanian which is undergoing fire induced population collapse in the Tasmanian alpine region, remaining within the burnt area, standing some 2 m above the slowly regenerating successional alpine community. A quick transect survey was taken across a fire scar near Backhouse Tarn, Mount Field. This area was burnt some 30 years previous due to a spot fire from a Forestry burn off. The dominant species in the unburnt vegetation was Athrotaxis cupressoides and a variety of sub dominant heath species whereas, across the fire scar, the vegetation was significantly smaller, with only one species above groundcover level and significant patches of bare ground. The most common plant was Astelia alpina at ground level with Orites revoluta, Diselma archerii and some Athrotaxis cupressoides emerging. Overall the species diversity of the unburnt section was lower than the burnt, recovering section as the burnt plant community endeavours to reestablish and follow a floristic path toward an eventual climax community, like the unburnt section, in the not so distant future. Significant areas of Tasmanian alpine country has been burnt since European invasion, to the extent that it is not conclusively known exactly what the composition of alpine communities was before the fire regime changed after this invasion. It is considered that the Aboriginal Tasmanians didn't actively burn alpine heathy zones but highly probable that they burnt alpine grasslands frequently for the purpose of hunting, however it is likely that alpine heath areas were infrequently burnt from ember attack from natural or Aboriginal fires. It is considered that, in the very long term, alpine communities are resilient to very rare fire events but the regeneration from these events to a climax community is in the order of decades or even centuries.