Late Quaternary vegetational history of the West Sumatran Highlands
A palynological investigation of sediments from montane West Sumatra (c. 1500 m a.s.l.) was carried out. Two fossil cores were examined. One, Danau di Atas, is at least 31000 uncorrected radiocarbon years old, and is relatively well dated: pollen influx values were calculated for this core. The second, Telago, is of Holocene age. To aid interpretation of these, the present vegetation of the area was studied, using plots, and pollen rain produced by this vegetation was also examined, using moss polsters and surface samples taken from within the plots. Pollen rain on a high mountain, Gunung Kerinci, south of the main field area was also studied. The modern pollen studies demonstrate the importance of canopy taxa in the regional pollen rain and aid in elucidating the relative pollen production of many taxa. The pollen assemblages recovered from both cores suggest a number of changes, both in the independent hydroseral development at the two sites, and dry land vegetation. The dry land vegetation changes have been interpreted in terms of environmental change and indicate that climates were formerly cooler, particularly from c. 17900 to c. 12900 years a.p., when the vegetation of the area included an important gymnosperm element. During this cool period mean annual temperatures were between 1.6 and 5.2°C cooler than at present. There is however no evidence to suggest that the climate was drier, or more seasonally dry, than at present during the period represented by the sequence. Changes in the vegetation due to human interference may have occurred on a minor scale up to 8200 years ago, but widespread forest clearance appears to have been a relatively recent phenomenon.