The estimation of temporal processes in tropical rain forest: a study of primary mixed dipterocarp forest in Indonesia

In the absence of growth rings it is difficult to give a precise time scale for pro- cesses associated with the re-establishment of tropical rain forest. This paper explores other methods by which a time scale may be constructed. The proportions of primary and secondary species, an index of similarity, biomass measurements, girth dimensions and gap size are all considered from sites in East Kalimantan, Indonesia. Data from primary, secondary and experi- mentally cleared forest sites are compared to estimate the minimum time required for various phases involved in the re-establishment of tropical rain forest after disturbance. A simple model is proposed to accommodate the data and other estimates in the literature. The model predicts a minimum period for the stablization of secondary species numbers as 60-70 years and the replacement of primary species as 150 years at which point gap formation is initiated. After approximately 220-250 years biomass stabilizes while individual trees exist for over 500 years.