Classification of Under-storey Vegetation Types in a Secondary Hill Dipterocarp Forest in Relation to Silviculture Planning m Brunei Darussalam

Summary : The under-storey vegetation in the Proposed Plantation Area(PP A) neighbouring on the Andulau Forest Reserve in Brunei Darussalam was studied. The purpose of this study was to classify the under-storey vegetation types and clarify the relationships between topography, soil and vegetation types. Species composition and the coverage of each species were studied by the quadrat· method. Ninety-eight plots (size, 2m X 2m) were set on the study site every 20m along south to north survey lines. Under-storey vegetation was categorized into four types : Dipterocarp seedling or sapling type (D·type), Monocotyledon dominant type (M·type), Fern dominant type (F-type), and non· dipterocarp woody species type (N -type). D-type is mainly distributed on the ridge of the eastern part of the study site. M-type is restricted to the gentle slope and bottom. F-type is randomly distributed on the western part of the study site. N -type is the basic vegetation of this area. The relationship between soil type and vegetation type is not clear, however, M-type is usually distributed in Yellow wet soil and F-type in Yellow dry or moist soil. Ecological studies and zoning of the study site were found to be necessary.