Biomass and tree diversity in a fragmented secondary forest in Tanah Laut Regency, South Kalimantan Province, Indonesia

In the tropics, the area covered by degraded and fragmented secondary forests has expanded following forest fires and intensive land-use. We studied a fragmented secondary forest in South Kalimantan Province, Indonesia, to gain ecological information and to quantify the effect of human activities on accumulated biomass and tree composition. A fragmented secondary forest of about 0.5 ha was divided into 27 edge and 18 inside plots with size of 10 m×10 m and the stand biomass, tree composition and human activities were analyzed. Mean aboveground biomass (AGB) in edge and inside plots were 63.2 and 71.2 Mg ha^-1, respectively and the difference was insignificant (t-test: p＞0.1), while the Shannon-Wiener index (H') value of the later tended larger than former (t-test: p＜0.1). Native trees tended to be more in inside plots comparing with edge plots, and human planted trees were identified in mainly edge plots. There were also large differences in biomass (wood) removal by rural people (1.350 and 0.248 Mg ha^-1 year^-1, respectively). The characteristics of each type of fragmented secondary forest were influenced by the human activity of wood collection: small-diameter trees, which should have been successors to the existing canopy, were frequently removed.