Geoffrey S. Hope and Simon G. Haberle
1982, 1984) and at Telefomin (1500 m asl; Gillieson & Hope 1989) forest cover dominated the valley floors with some minor fire disturbance being recorded.
Figure 2: Charcoal histories through time from selected sites in New Guinea (Figure from Haberle et al. 2001)
As global temperatures warmed and glaciers retreated, the late glacial transition in the highlands was achieved in a two-phase warming sequence with an initial period of climatic instability between 14,500 and 12,000 BP, followed by a more persistent warming between 12,000 and 8500 BP. At high altitude this led to an elevation in forest growth limits and a replacement of treeferns and grasslands with a closed upper montane forest (Hope 1989). In the highland valleys the combination of increasing mean annual temperatures, high atmospheric CO2, and strengthening monsoon influence (Haberle et al. 2001) would be expected to result in expansion of forests into grassland habitat. This process is retarded in the Haeapugua and Kuk Swamp (reported in Powell 1984 and Denham et al. 2004) sites where burning is persistent and frequent from around 21,000 to 8500 BP, resulting in the maintenance of grasslands at a time when forests are expanding in other areas. In response to increasing temperatures a shift in composition of existing forests occurs from a Nothofagus dominated community to a more mixed Nothofagus forest incorporating forest taxa from lower altitudes such as Castanopsis/Lithocarpus and Myrtaceae. Climate stability during this time may have been disrupted by a strengthening and possibly unstable monsoon system coupled with enhanced El Niño-related climate variability, resulting in an increased incidence of frost and drought (Haberle et al. 2001). This may have increased the probability of fire in the highlands, however, the increase in archaeological evidence for human occupation sites during this period points to an alternative interpretation. This is