Changes in tree species distribution along altitudinal gradients of montane forests in Malaysia

Abstract

Lowland and montane forests can be distinguished as being distinct floristically and by their structural characters. Soil and climatic factors are primary determinants of changes in community structure and species composition. Field surveys were undertaken in the pristine forests of Imbak Canyon, Sabah and Mount Ledang, Johor, Malaysia. While these areas provide long-term maintenance and fully protected habitats of biological diversity, the floristic composition still remains rather insufficiently known. Therefore, this study has three objectives: (1) to identify the major forest types and tree communities, (2) to study changes in species composition along altitudinal gradients, and (3) to document the list of tree species collected in the study areas. The survey in Imbak Canyon resulted in the documentation of 40 families of the Angiosperms and Gymnosperms comprising 85 genera and 149 taxa. The areas are rich with tree species from the families of Dipterocarpaceae, Guttiferae, Lauraceae, Leguminosae, and Myristicaceae. Trees from Podocarpaceae family are common montane taxa occurred in highest peak of ridge trail such as Podocarpus neriifolius, Dacrydium elatum, Phyllocladus sp., and Falcatifolium falciforme. An interesting finding was the occurrence of Shorea monticola (Dipterocarpaceae) in the summit zone of montane heath forest, whereas in Mount Ledang, a total of 62 tree families were encountered which consist of 62 families, 143 genera, and 222 taxa. Overall, Mount Ledang is rich with the tree species from the families of Myrtaceae, Euphorbiaceae, Moraceae, Dipterocarpaceae, and Rubiaceae. Common montane taxa encountered include trees from Podocarpaceae family (i.e., Podocarpus neriifolius, Dacrydium elatum, and Dacrydium beccarii). An interesting finding was the discovery of Maesa fraseriana (Maesaceae) in the upper montane forest of Mount Ledang which can potentially be a new record for the area. Information from this survey may provide a valuable reference for forest assessments, and improving our knowledge in identification of ecologically useful species as well as species of special concern, thus identify conservation efforts for sustainability of forest biodiversity.