Forest Structure and Productivity of Tropical Heath and Peatland Forests

Allometric relationships between tree dimensions, aboveground forest structure and productivity were examined in tropical heath (kerangas) forest and peatland forest in Central Kalimantan, to determine the stand level properties of these forest types growing under stressful conditions, by comparing with those in mixed dipterocarp forests. In the peatland forest, tree density, trunk diameter-height relationships and aboveground biomass differed between sites, partly due to differences in disturbance history such as the intensity of selective logging in the past. The heath and peatland forests shared common characteristics such as high leaf mass per area and long leaf residence time at the stand level. Both forest types had high wood mass increment rates (maximum of 8.2 Mg ha−1 year−1 in the heath forest and 10.9 Mg ha−1 year−1 in the peatland forest), which fluctuated greatly during and after the severe 1997–1998 drought. The results here suggest that the heath and peatland forests maintain moderately high productivity under stressful conditions, probably owing to the adaptive leaf properties. The results also suggest that the aboveground forest structure of these forest types as well as peat deposit has the potential to play a significant role in the carbon balance in an area. To be able to properly conserve these forest ecosystems, more attention must be paid to elucidating the mechanisms maintaining primary productivity of heath and peatland forests.