Burraga Swamp is a small enclosed basin at 985 m altitude in Barrington Tops, in the Eastern Highlands of New South Wales, Australia. It lies in the midst of a Nothofagus moorei cool temperate rainforest, which is at its southern limits here. The swamp is close to the boundaries between temperate rainforest, subtropical rainforest, sclerophyll forest and sub-alpine formations and may be a sensitive recorder of past changes in the vegetation.
The palynology and the sediments have been studied to a depth of 6.5 metres and were dated with eleven 14C dates. The base of the sediment is about 40,000 years old.
The results showed the following:
From 40,000-30,000 years BP, Burraga was a lake with a very slow rate of deposition of fine grained sediments and flourishing aquatic/swamp vegetation. The dryland vegetation was an open or sparsely treed grassland/herbfield. From 30,000-21,000 years BP, the dryland vegetation remained much the same, but the aquatic vegetation disappeared. From 21,000-17,000 years BP, sandy sediments were deposited at an accelerated rate in a relatively shallow lake, culminating in a layer of gravelly sand. The vegetation was a treeless grassland between about 21,000 and 15,000 years BP. After 17,000 years BP, the rate of sediment accumulation slowed and after 15,000 years, some mesic elements appeared. Dicksonia antarctica became prominent between about 13,000 and 12,000 years BP and Nothofagus was consistently present after about 11,500 years BP. Peat deposition started about 6,500 years BP. By 6,000 years BP the cool temperate rainforest was fully developed, remaining on the site until the present.
These changes suggest that the climate at 40,000 years BP was drier than the present, becoming drier and reaching maximum aridity about 17,000 years BP, when temperatures were also at their lowest. Subsequently, the temperature increased and around 15,000 years BP the climate became wetter. Maximum moistures and temperatures were reached between about 9,000 and 5,000 years BP. The climate then varied until it reached the present.
Burraga extends the record of treeless vegetation over most of southeastern Australia, during the last glacial maximum, to more northerly localities than previously known.
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