Dependency on topographical habitat was examined for Lauraceae tree species in a lower montane forest using a large‐scale research plot established at Doi Inthanon National Park, northern Thailand. Twenty species of 10 genera of Lauraceae were recorded in a 7.5‐ha part of the plot; Lauraceae accounted for 18% of the total basal area. Lauraceae was the most species‐rich and most abundant family in the plot. In a cluster analysis based on the matrix of spatial associations between species, two clusters were recognized. Members of one cluster seemed to associate with lower‐elevation habitats, and members of the other associated with habitats on ridges. By subdividing the study plot into 20 m × 20 m squares, a discriminant analysis could be applied to the presence–absence data for the 17 species that had sufficient population density. The predictor variables used were the relative elevation, slope inclination, slope direction (transformed to deviation from SSW) and slope convexity for each of the squares. The discriminant models were tested statistically by applying the random shift technique. The models were significant for 11 of the species (65% of the species examined) and were associated with the topographical condition of the habitat. Stepwise selection of the predictor variables for these 11 species revealed that relative elevation and slope convexity were the most important factors for predicting the presence or absence of the Lauraceae species. Both these variables were considered to indicate the hydrological condition of the habitat.

The study was aimed to study water quality treated by mangrove forest. This study has been conducted at the mangrove forest site of the King's Royally Initiated Laem Phak Bia Environmental Research and Development Project (the Royal LERD Project), Ban Laem District, Phetchaburi Province, Thailand. The study site, where Avicennia marina is dominant plant, is divided into in 3 areas; (A) the tideland area between constructed pond and mangrove forest, 200 meters from outlet (B) area of mangrove forest, distance 201 to 900 meters from outlet and (C) sea area, started from 901 meters from outlet. Six parameters were investigated; including temperature, pH, dissolved oxygen (DO), phosphate, nitrate, and ammonia. The results showed that water quality from mangrove forest met the effluent standards for coastal aquaculture (Ministry of Natural Resources and Environment, 2004). Mangrove forest can be able to improve water quality by increasing DO by 32.39%, while reducing phosphate, ammonia, and nitrate by 88.23%, 73.77%, and 64.28% respectively. It can be used as an additional natural system to increase the efficiency of man-made wastewater treatment system.

Abstract-Tha