Changes in forest community structures of tropical montane rain forest on the slope of Mt. Trus Madi in Sabah, Malaysia

Changes of the forestcommunity structures in relation to increasing altitude were studied along the slopeof Mt. Trus Madi in Sabah, Malaysia. The total number of species, Shannon-Wienerdiversity index, Menhinick richness index, rarefaction index, mean diameter, meanbasal area, mean biomass and mean tree height were higher at 600 m (plot 1) anddeclined 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 increasedin ascending order at 1400,1800 and 2400 m. The dominant and co-dominant specieswith the highest and second highest importance values were different between plots.Shorea dasyphyttaznA S. agami were dominant at (500 m, and were replaced respectivelyat 1400,1800 and 2400 m by Phyllocladus hypophyllus and Eugenia ampullaria, E. hirtaand Knema latericia, and E. kinabaluensis and Leptospermum recurvum. Family Myrtaceaewas dominant at all elevations except at 600 m, which was dominated byDipterocarpaceae. Families Polygalacea, Podocarpaceae, Clusiaceae and Theaceaewere dominant at 600,1400,1800 and 2400 m respectively. The biomass of trees wasdistributed unevenly between species and family at all altitudes. The most dominantspecies and family by biomass at 600 m were Pamshorea sp. and Dipterocarpaceae; at1400 m they were S. dasyphylla and Dipterocarpaceae; at 1800 m Garcinia dryobalanoides,and Clusiaceae; and at 2400 m E. kinabaluensis and Myrtaceae. Regression, ANOVA andcoefficient of determination indicate significant negative relationships between thenumber of species, Shannon-Wiener diversity index, Menhinick richness index,rarefaction index, mean diameter, mean basal area, mean biomass and mean treeheight with increasing altitude. However, there was a very significant increase indensity, Simpson diversity index and species evenness with increasing altitude