Spatial distribution of abundant tree species at a mixed dipterocarps forest in Bukit Bangkirai, East Kalimantan three years after long drought and forest fire

Abstract

Siregar M. 2017. Spatial distribution of abundant tree species at a mixed dipterocarps forest in Bukit Bangkirai, East Kalimantan, three years after long drought and forest fire. Pros. Sem Nas Masy Biodiv Indon 3: 246-251. This study aims to determine the distribution of abundant tree species that survive or grow three years after long drought and forest fires. The tree distribution data were extracted from the database of three permanent plots at Bukit Bangkirai, namely: 1.0 ha plot at heavily damaged forest due to forest fires (HD-plot), 0.3 ha at lightly damaged forest due to forest fires (LD-plot) and 1.0 ha plot in a natural unburnt forest (K-plot). The distribution pattern was analyzed by using Morisita's indices of dispersion and Jaccard's indices of species association. Correlation of tree density with height and slope of land were also analyzed in each plot.The results showed that the most of the abundant tree species were clumped at small scales, and the clumps were randomly distributed (inter-clump distribution is random). An exception was found for Macaranga glaberrimus at K-plot and Madhuca kingiana at LD-plot which have random distribution both on small and large plots. Individuals of M. kingiana in K-plot were clumped at larger scales, and they were distributed uniformly within the clumps (intraclump distribution is uniform), which were distributed in the valley and steep slope. Inversely, Shorea laevis is rarely found in valleys and steep slopes. In HD-plot, distributions of Macaranga gigantea, Homalanthus populneus and Mallotus paniculatus were concentrated in the valley and in the lower parts of the slopes which have water availability. It can be concluded that the distribution of secondary species in HD-plot is much influenced by water availability, whereas in LD-plot and K-plot more affected by light availability