3rd IASME/WSEAS Int. Conf. on Energy & Environment, University of Cambridge, UK, February 23-25, 2008 Floristic Diversity, Composition and Richness in Relation to Topography of a Hill Dipterocarp Forest in Malaysia SAIFUL, I. Forest Department Headquarters Ban Bhaban, Mohakhali, Dhaka, BANGLADESH FARIDAH-HANUM, I., & KAMARUZAMAN, J Faculty of Forestry Universiti Putra Malaysia 43400 UPM Serdang, Selangor MALAYSIA LATIFF, A. Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, MALAYSIA. Abstract: - A study along the gradient directed transect was conducted in a hill dipterocarp forest at Ulu Muda Forest Reserve, Kedah, Peninsular Malaysia to study tree species composition, distribution, richness and diversity in relation to topography. A total of 2,421 individuals belonging to 421 species, 187 genera and 57 families across all size classes of trees from 1.5-m height and above were enumerated and identified. The species number represents 15% of the total tree species recorded from Peninsular Malaysia of which 47 were endemic and 22 rare species. Seventy four species were new records for the state of Kedah while one species Nephelium hypoleucum was a new record for Peninsular Malaysia. The distribution of species and individuals in families as well as the distribution of species with different sizes of stems followed an inverse J-shaped pattern. Euphorbiaceae and Dipterocarpaceae represented as two most dominant families. Shannon’s index of diversity registered a higher diversity index of 5.61 for the study site as a whole than other reported figures elsewhere. Species accumulation curves for different tree size classes showed no tendency to flatten out but continue to rise. A total of nine dominant species showed strong association with topography when subjected to the chi- square test. Multivariate cluster analysis and Principal Component Analysis (PCA) detected the topographic component of floristic variation between different topographic locations. Key-Words:- Tree species, Accumulation curve, Composition, Distribution, Topography, Hill forest, Richness, Distribution 1 Introduction and variation in sites in a diverse forest [2]. Spatial heterogeneity which refers to the Further, topographic aspect of floristic variety of habitats presents within an area and variation cannot be detected through such a disturbance have been acknowledged for high small plot study [3]. Gradient directed species diversity in the tropics [1]. Most of the transects are commonly applied to detect studies on rain forest structure and diversity variation in vegetation distribution along the have been done in a single plot, at or near the 1 environmental gradient [4],[5]. ha level, probably because of great richness of Hill dipterocarp forest is characterized tree species. Such single plot approach may be by undulating to very steep slope and currently inadequate to represent the full range of in Malaysia constitutes the bulk of the floristic composition and species richness data productive Permanent Forest Estate. The ISSN: 1790-5095 Page 398 ISBN: 978-960-6766-43-5 3rd IASME/WSEAS Int. Conf. on Energy & Environment, University of Cambridge, UK, February 23-25, 2008 objective of this study was to evaluate tree predominantly made up of quartzite and species composition, distribution, richness and sandstone [6] giving rise to clayey and sandy diversity in relation to topography. It was part texture. Within the study area, the soil type is of the larger study on the effects of selective also classified as Baling and Tai Tak series [7] logging on tree species diversity, stand which are yellowish brown in colour and structure and physical environment of tropical finely textured well drained. However, there hill dipterocarp forest of Peninsular Malaysia are also local variations in soil colours with [3]. respect to topographic locations [3]. 2 Methods 2.2 Methodology Based on the topographic map (1: 50,000) of 2.1 Site Description the study site, two adjacent blocks consisting The study was conducted in the Sungai Weng of 100 hectares, as shown in location map, was Catchment of Ulu Muda Forest Reserve, selected for systematic sampling. As Kedah, Peninsular Malaysia (5° 50′ N; 100° topographic positions have strong influence on 55′ E) (Fig. 1), in five compartments viz. C25, species composition [8],[9]and [10], the study C26, C27, C28 and C29. The elevation of the site was also stratified into four microhabitat study area ranges from 340 to 600m above sea types (strata) which are streamside, ridge, level and characterized by a hilly and ridge-top and hillside (Fig. 2). undulating terrain with moderately steep to A systematic sampling along the gradient directed transect [11]was applied to very steep slopes (up to 45°). conduct the biodiversity survey of the study area. Within each stand, a line transect of about 500-600m in length was laid out originating from stream bank and following the center of the ridge and finally ending at a ridge crest (Fig. 2). Transect line had never been laid out across the ridge or valleys to avoid the periodic trends of capturing same habitat type (e.g. either ridge or valleys). Instead, by surveying individual stand, it systematically covered all existing topographic positions. Lateral transects were also established at right angle to the main transect to sample the hillsides, and spaced systematically at 40-m apart. All transects were deliberately positioned at right angle to the contours in order to capture maximum range of variation in slope and soil condition. Fig. 1: Left: Topographic map (1: 50 000) of Study plots were also established at a 40-m Ulu Muda Forest Reserve, showing location of apart on the transect line. Trees of ≥ 20.0 cm study area and compartments. Right: Map of diameter at breast height (dbh) were measured Peninsular Malaysia showing study location within the main plot of 30 x 30 m or 20 x 45 m (asterisk). size and three kinds of nested subplot such as 10 x 10 m, 5 x 5 m, and 2 x 2 m are distributed The climate of the study area is uniformly hot inside the main plot for poles(5.0 cm to < 20 averaging about 25° C mean daily minimum cm dbh), saplings (1.5 m ht. to < 5.0 cm dbh) with ample rainfall almost throughout the year. and seedlings (10 cm to < 1.5 m tall) The mean annual rainfall for the three-year respectively. The detail of the plot design is period (1996-1998), recorded from the rainfall shown in Fig. 3. stations established within the study site, averages 2869 mm. The parent material is ISSN: 1790-5095 Page 399 ISBN: 978-960-6766-43-5 3rd IASME/WSEAS Int. Conf. on Energy & Environment, University of Cambridge, UK, February 23-25, 2008 between the two sets of variables, and carried out a simple linear regression to find the best- fit line. The spatial association of tree species with respect to topographic positions was examined using Chi-square test. A t-test was applied following the method described by [12] to compare the diversity of two habitats. Statistical significance levels were established at P< 0.05. Analysis was performed with the Fig. 2: Topography of the study area showing Minitab (Release 10 for Windows) statistical direction of survey transects (indicated by package [13]. arrow) follows elevation gradient. Lateral Margalef’s and Menhinicks’s indices transects on hillsides are not shown. were us ed to indicate species richness; and three species diversity indices which are Fishers’s, Simpson’s and Shannon’s indices were used to show and compare different topographic locations [12]. To detect pattern of similarity or dissimil arity in species composition between different topographic locations in the study site, a multivariate cluster analysis of the habitat-wise data was undertaken. The single- linkage clustering (nearest neighbour method) was used based on species abundance data for each stratum (for trees 1.5-m height and above). Fig. 3: Schematic diagrams of plot design The Principal Component Analysis showing different shape and sizes of plots for (PCA), another multivariate method was enumeration of various tree size classes. further employed to detect the effect of topography in species distribution by 2.3 Data Collection ordination of sample plots; hence its pattern Diameter at breast height (DBH) of all trees from a large data set. according to the diameter class selected for different plot size (described above) was 3 Results and Discussion measured with a diameter tape at 1.3 m above ground level or just above the buttress. 3.1 Taxonomic Composition Seedlings were recorded by counting. Except A total of 2410 individuals with 57 families, seedlings, spatial positions of individual trees 187 genera, and 421 species across all size according to diameter class and plot size used classes from 1.5-m height and above were were also mapped. All plants measured were recorded and identified within the study area. identified up to the species level in the field; The details on the number of genera, species when impossible to do so voucher specimens and individuals as well as a detail list of tree were collected and identified in the herbarium. species composition with abundance of each Voucher specimens were deposited in the species are available elsewhere [3]. The family herbarium of Universiti Kebangsaan Malaysia dominance was predominantly attributed to 10 (UKMB). large or commonest families based on number of species and individuals. Euphorbiaceae was 2.4 Data Analysis found to be the most diverse family having 44 The underlying distribution of data set was species or 10.5% of the total number of species examined by using histogram to distinguish recorded followed distantly by Lauraceae (30 symmetric from a skew distribution. For species or 7.1 %), Myrtaceae (24 species or 5.7 skewed data set, data were log-ten transformed %) and Annonaceae (22 species or 5.2 %).