抄録
Long-term observations were conducted over the last 16 years to assess the degradation processes within a secondary forest in an equatorial region in Sumatra Island. Two belt transects representing 5.6 km × 10 m in total and two permanent plots of 1.8 ha were used. A secondary forest located below 300 m in altitude was largely lost over the last 8 years, and this deforestation, which was largely caused by clearing for fields and logging for timber by the local people, expanded to a forest at 500 m in altitude, 3 km from the nearest village. Based on the mortality of the trees with the examined parameters (density and basal area) and distance from the village, we concluded that a secondary forest below 500 m in altitude will be greatly retrogressed within the next 16 years, and the original floristic features of a hill forest below 1050 m in altitude will disapper within next 32 years.
