The vegetation of an infrequently burned Tasmanian mountain region

Abstract

The Mt. Bobs-Boomerang area in southern Tasmania is rugged and mountainous (600-1080m above sea level), with a perhumid cool (Thornthwaire classification) climate and a range of geological substrates inclucling mudstone, sandstone, limestone and dolerite. 164 species of vascular plants, all native to Tasmania, have been recorded in the study area. The subalpine vegetation is composed primarily of rainforest and scrub communities. Fires have had major effects on these communities, but are rare; the period since the Last fire varies between about 50 and 500 years. A small area of herbland and heathland occupies the poorly drained valley fioors and different herbland communities are found on the flats and limestone cliffs around Lake Sydney. Above the treeline, which occurs at about 1000m on Mt. Bobs and the Boomerang, heathland is the major vegetation formation. Herblands are found in sheltered sites with the longest snowlie, and fjaeldmark, much of it associated with a pattern of non-sorted solifluction terraces, occupies the highest, most exposed part of the mudstone-capped Boomerang. Exposure to strong winds, snowlie, substrate type, degree of waterlogging and fire frequency appear to be major environmental delerminants of the plant communities.