Two specific problems are identified in understanding the data on the
Quaternary of Montane areas in the Sunda-Sahul region. These are: (1)
The Upper Montane rainforest, according to palynological evidence, app
ears to have been absent in the Late Pleistocene, although it is well
represented today. (2) The estimates of temperature lowering in the La
te Pleistocene are strikingly greater in the mountains than in the low
lands. A single possible explanation for both problems is proposed. It
is argued that altitudinal zonation of vegetation is partly controlle
d by ultraviolet-B light which is strikingly increased at high altitud
es in the tropics. This fact could account for both the above problems
, not only in the Sunda-Sahul region, but also in other tropical regio
ns. Copyright (C) 1996 Elsevier Science Ltd