Alpine and subalpine vegetation

​​Tasmanian alpine and treeless subalpine vegetation is globally unusual due to the dominance of hard leaved shrubs and sedges. Another distinctive feature of the vegetation is plants with a cushion (bolster) form. It exhibits high species diversity, and a high level of endemism (species only found in Tasmania). It is also a stronghold for paleo-endemic species which are species which trace their origins back to ancestors which inhabited Gondwana.  These species typically have few or no adaptations for surviving fire, or recolonising post fire.

Alpine vegetation, Southwest National Park (Image: Steve Leonard)

Depending on long-term fire history and the species present, the impact of fire on alpine vegetation communities can range from severe, where communities are unlikely to recover to their former state or are permanently lost, through to moderate where communities will recover providing repeat burning does not occur in the medium-term.

The fire sensitivity of alpine vegetation is often dependent on the context of the vegetation in the landscape.  Topographically protected areas which have historically been protected from bushfires and cultural burning have developed into highly fire sensitive communities.  Other areas which have been subjected to occasional bushfires or cultural burning support vegetation which is consequently more fire adapted.

Some western heaths and protected eastern heath communities, contain high amounts of paleo-endemic and other fire killed species and may be permanently eliminated from a site by a single fire. Other alpine and subalpine heaths are dominated by more fire adapted species and these, along with alpine sedgeland and grassland communities, can regenerate from seed or by resprouting. Similarly, recent research has shown that cushion plants may be resilient to fire as long as the fire does not penetrate the cushion surface and combust the peat below the cushion surface. The resilience of cushion plants to fire is also likely to vary amongst species.

In the harsh alpine environment regeneration of all communities can be slow. This can in turn leave the soil exposed to erosion.  In some situations once erosion has commenced it can progress for many decades and permanently alter the vegetation.