Abstract
The altitudinal gradient of vegetation of the Barisan range in a coastal region near Padang, West Sumatra, was studied in 10 plots (0.1-6.55 ha) distributed from 600 to 1780 m. Trees with a diameter at breast height of more than 10 cm were employed for classification of the vegetation. Four vegetation zones, two types of montane and two types of lowland vegetation, were recognized based on cluster analysis, floristic information, and the physiognomy of these forest stands. An upper zone of montane vegetation (Lower montane Fago-Myrtaceous forest) was distinguishable from a lower zone (Sub-montane Fago-Myrtaceous forest) due to the remarkable dominance of several species of Fagaceae and Myrtaceae, and its lower canopy height. The two zones of lowland vegetation (Upper hill dipterocarp forest and Mid-hill dipterocarp forest) were distinguishable by their species composition of Dipterocarpaceae and stratification of the stand. The altitudinal zonation corresponded well with classic zonation patterns previously reported for West Malesia, but the critical threshold altitudes were lower in comparison with those in other regions. The borderline between the lowland and montane vegetation, corresponding to a Kira’s warmth index of WI = 180 °C · month, was around 200 m lower in Padang than in other regions of West Malesia, and the critical altitude between the two zones of lowland vegetation was also around 300 m lower in Padang than on Mt. Kinabalu. The characteristics of altitudinal zonation in Padang were discussed with reference to the climatic features of this region, namely, the low temperature and hyperhumidity.
