CHANGES IN FOREST COMMUNITY STRUCTURES OF TROPICAL MONTANE RAIN FOREST ON THE SLOPE OF MT. TRUS MADI IN SABAH, MALAYSIA

Abstract

Changes of the forest community structures in relation to increasing altitude were studied along the slope of Mt. Trus Madi in Sabah, Malaysia. The total number of species, Shannon-Wiener diversity index, Menhinick richness index, rarefaction index, mean diameter, mean basal area, mean biomass and mean tree height were higher at 600 m (plot 1) and declined in descending order at 1400 m (plot 2), 1800 m (plot 3) and 2400 m (plot 4). Density, Simpson diversity index and evenness index were lower at 600 m and increased in ascending order at 1400,1800 and 2400 m. The dominant and co-dominant species with the highest and second highest importance values were different between plots. Shorea dasyphylla and S. agami were dominant at (500 m, and were replaced respectively at 1400,1800 and 2400 m by Phyllocladus hypophyllus and Eugenia ampullaria, E. hirta and Knema latericia, and E. kinabaluensis and Leptospermum recurvum. Family Myrtaceae was dominant at all elevations except at 600 m, which was dominated by Dipterocarpaceae. Families Polygalacea, Podocarpaceae, Clusiaceae and Theaceae were dominant at 600,1400,1800 and 2400 m respectively. The biomass of trees was distributed unevenly between species and family at all altitudes. The most dominant species and family by biomass at 600 m were Parashorea sp. and Dipterocarpaceae; at 1400 m they were S. dasyphylla and Dipterocarpaceae; at 1800 m Garcinia dryobalanoides, and Clusiaceae; and at 2400 m E. kinabaluensis and Myrtaceae. Regression, ANOVA and coefficient of determination indicate significant negative relationships between the number of species, Shannon-Wiener diversity index, Menhinick richness index, rarefaction index, mean diameter, mean basal area, mean biomass and mean tree height with increasing altitude. However, there was a very significant increase in density, Simpson diversity index and species evenness with increasing altitude.