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

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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

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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 %). to obtain symmetric distribution for calculation Similarly, Euphorbiaceae was also dominated of mean value. Pearson correlation coefficient by large number of stems (371) but followed was determined to find out relationship

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distantly by Dipterocarpaceae, Annonaceae and Leguminosae with 158, 134 and 131 stems respectively. However, Euphorbiaceae and Annonaceae were mainly confined to the understorey and medium-sized trees and did not generally exceed 50 cm in diameter whereas Dipterocarpaceae was the most abundant family in the overstorey canopy. There were 47 Peninsular Malaysian endemic s and 22 rare tree species recorded from the study area. These species were distributed in all topographic locations. The endemic species constitute 6.3 % of the total endemic tree species recorded from Peninsular Malaysia. Only five dominant families i.e. Annonaceae, Euphorbiaceae, Guttiferae, Lauraceae and Myrtaceae contributed 42 % of the total endemic species of the study area. A total of 74 species which were previously known only from other states of Peninsular Malaysia were recorded for the first time for the state of Kedah. These new records also constitute 17.6 % of the total species recorded from the study site. There is also one new record of species for Peninsular Malaysia, Fig. 4: Distribution of families with different Nephelium hypoleucum (Sapindaceae). The number of species (a) and individuals (b) in the detail list of species including endemic and study site. Both curves are inversely J-shaped rare is reported elsewhere [3]. with many small families and few large. . 3.2 Distribution Pattern of Taxa Table 1: Distribution of species abundance in The frequency distribution of families of the study site, Ulu Muda Forest Reserve under different sizes of species and individuals in the various abundance categories. study site showed a definite pattern of skewness with inverse J-shaped distribution Abundance Range No. Percent particularly evident in tropical rain forest category size species (Fig.4). The distribution of species was Rare 1-10 362 86.0 stems categorized under different sizes of individuals Occasional 11-20 41 9.7 (Table 1). Those species with only one stems individual were considered as very rare. Frequent 21-30 10 2.4 Species between 1-10 stems constitutes 86 % stems of the total species sampled and were Common 31-40 2 0.5 stems categorized under rare species. Such a low Very common > 40 6 1.4 abundance is generally regarded as stems constituting a high proportion of species Total 421 100 richness in tropical rain forests [9]. However, with the increasing range size (Table 1), the Based on apparent topographic number of species is shown decreasing except preference of 32 dominant species (in terms of at the end that indicates inverse J-shaped number of individuals), only 9 species have distribution. At habitat level, the pattern of J- shown significant association with the curves between stream and ridge top, and topography when subjected to the chi-square between hillside and ridge were almost similar. test (Chi-square = 59.82, P < 0.001, df = 16). This similarity has also significant bearing in Since, chi-square analysis is meant for the diversity structure of the different habitats relatively abundant species, species from and is explained in the relevant section. streamside did not qualify for chi-square test when examined. Palaquium herveyi,

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Monocarpia marginalis and Ochanostachys Table 2: Species richness data from the study amentacea were highly dominant in the site for trees 1.5 m height and above, and hillside and ridges, whereas Aporusa falcifera, Margalef’s and Menhinicks’s index values for Epiprinus malayanus and Archidendron species richness. bubalinum showed a high preference for ridges. Shorea curtisii, previously reported as Stratum No. No. Margalef’ Menhinick Stem Spp. index index the dominant species in the ridge tops of hill Streamside 241 129 23.36 8.31 dipterocarp forest of Peninsular Malaysia [8] Hillside 772 252 37.74 9.07 also showed a high preference in the ridge Ridge 907 269 39.41 8.93 tops. A fair degree of association of Shorea Ridge top 490 178 28.59 8.04 Under 1323 332 44.65 8.85 macroptera and Mallotus kingii were confined storey within ridges and hillsides respectively. [10] (<20cm dbh) Over 1087 287 40.92 8.70 showed similar result on association of few storey dominant species with the topography from (≥20cm dbh) Puerto Rico while [14] also reported thirteen All strata 2410 421 53.92 8.58 most common tree species from Peninsular Malaysia.

3.3 Species Richness The species richness and calculated index values for species richness are summarized in Table 2 according to topographic locations as well as over and understorey richness of species. The variations in the number of species were due to the variation in the number of individuals. This is evident from significant positive correlation exist between number of species and number of individuals at all strata level with a high R² value of 0.97 (Fig. 5) showing best fit regression line. The values

calculated by Margalef’s index indicate that Fig. 5: Positive linear correlation between the index is sensitive to sample sizes (i.e. species richness and number of individuals at number of individuals) [12]. However, stratum level in the study site (derived from Menhinick’s index showed different trends Table 2). with little effect on sample size, and

discriminated streamside from the ridge top by Table 3: Species-individual ratios between distributing higher value. Similar trends were habitat types of the study site. also observed in the case of other strata. This

can be interpreted by saying that stratum Stratum No. No. Species- (habitat types) with lower species abundance species individuals individual would record higher Menhinick’s index value ratio after taking species richness into account. Streamside 129 241 0.54 Where sample size affects the species richness data, the species-individual ratio may Hillside 252 772 0.33 be used as a good indicator of species richness Ridge 269 907 0.30 for comparison of various sites. By this Ridge top 178 490 0.36 measure, tree species richness for streamside was significantly higher (Table 3) due to high species-individual ratios (i.e. lower species 3.4 Species Dive rsity dominance) than the other topographic The results of the use of different species locations. diversity indices for different topographic locations were compared. Table 4 shows that Fisher’s α increased with small sample (< 500 individuals) derived from streamside compared

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to relatively larger sample obtained from ridge values of species diversity, even though the top, but then increased with higher number of species composition were entirely different individuals recorded from hillside and ridge. had been also viewed by [16].

Table 4: Estimates of Fisher’s α based on Table 5: Species diversity indices for different number of species (S) and number of habitat types of the study site (Simpson index individuals (N) for four topographic (Ds), Shannon index (H'), Hmax (= In S), locations of the study site. Shannon Evenness). Shannon values with similar superscript are not significantly Stratum S N Fisher’s α different from one another by t-test Streamside 129 241 112.92 Hillside 252 772 130.19 Habitat Spp Stems Ds H’ H E Ridge 269 907 129.21 (S) (N) max Ridge top 178 490 100.52 Stream 129 241 0.98 4.79ª 4.85 0.99 High specie s diversi ty for Simpson’s and Hillside 252 772 0.99 5.52 0.92 Shannon’s indices were observed in all 5.07ƅ topographic locations (Table 5). However, Ridge 269 907 0.99 5.59 0.90 Simpson Index being heavily dependent on the 5.02ƅ most abundant species [12] calculated similar values for all strata and could not discriminate Ridgetop 178 490 0.98 4.75ª 5.18 0.92 one from another. It seems, therefore, that the index could not discriminate the minor All strata 421 2410 0.99 5.61 6.04 0.93 variations in species abundance pattern. In contrast, Shannon’s index of diversity accounted for large number of rare species and 3.5 Species-accumulation Curve contributed diversity index of 5.61 for the The species-accumulation curves were study site, which was in the higher range when construc ted to observe the trend in species compared to other available studies reported accumulation within the study site. Due to elsewhere [3]. However, based on t-test [12], unequal sample size with regard to topographic the Shannon’s index significantly varied (P< locations, the comparative features on species- 0.001) between the strata, and thus showed accumulation curve between them are limited. some effect on sample size (Table 5). As such However, species-accumulation curves were Shannon’s index had more discriminative constructed for three different diameter classes ability in distinguishing habitats than Simpson of trees and plot size used. All three species- Index. [12] also suggested Shannon’s index to accumulation curves showed no tendency to be more informative when comparing between flatten out but new species continues to sites, and also emphasized to examine the increase slowly within the study area (Fig. 6). shape of the species abundance distribution. In species rich rain forest, it has been shown The ratio of the observed diversity H' to the that species continued to accumulate even over Hmax which is indicative of measure of 4-5 hectares survey area particularly of those evenness [15] in the distribution of individuals. species, which are determined by habitat among the species was also observed high in conditions or by chance [22]. [23] also found all stratum but vary within a narrow range of that in three 50-ha plots tree species richness values (Table 5). The evenness component of continued to accumulate up to and beyond 50 diversity has finely discriminated streamside hectare, and asymptote was not reached at any and the ridge from other strata depending scale. solely on the degree of evenness in the distribution. As a result, streamside registered highest score and ridge registered lowest score while both hillside and ridge top recorded similar points (see Table 5). The sites with identical distributions of species in the tropical rain forest of Sumatra represented by the same

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while, most plots of stream and ridge tops grouped independently. Similar results were reported by [20] and [21] also demonstrated topographical aspect of floristic variation by PCA ordination from Brunei but [22] from Malaya found no perceptible variation of vegetation in relation to topography due to methodological limitations in his analysis [21].

Fig.6: Species-accumulation curves in the primary hill dipterocarp forest at Ulu Muda Forest Reserve. Note that all three curves showing no tendency to flatten out.

3.6 Cluster Analysis The resulting dendrogram (Fig. 7) showed that both hillside and ridge were more similar in Fig. 7: A Dendrogram showing hillside (C2) composition than the ridge tops, and and ridge (C3) as two most similar sites while streamside was different from others. Although stream (C1) is quite different from other the physical factors govern the distribution of strata.. species, but the intensity of sampling, plot siting and mode of analysis influence the detection of local variation in species composition [17]. At Pasoh forest, Peninsular Malaysia, [18] also demonstrated undulating and hill units to be grouped together and alluvium subplots sorted alone in different group. However, [19] could not detect the topographic component of floristic variation at Andulau, Brunei due to their plot size, which was too small to detect.

3.7 Principal Component Analysis (PCA) The graph resulting from this ordination technique is shown in Fig. 8. Altogether seventy species with more than five individuals were distributed in 62 plots used in the analysis. [20] also showed that a minimum number of species was required to provide sufficient information for an effective ordination. Scatter plot of the first two Figure 8: Principal Component Analysis using principal components (PC1 and PC2) (a) presence/ absence and (b) quantitative confirmed the three distinct groupings of the species data of 62 study plots of 900 m² each habitat types using both presence/absence and (for trees with dbh ≥ 20 cm) showing scatter quantitative species data. Most plots of ridge plot of the first two principal component (PC1 and hillsides were grouped together. They and PC2). Note quadrat ordination in relation were graphically positioned close together to topographic positions.

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[7]DOA (Department of Agriculture) 1994. 4 Conclusions Soil survey report of six forest The total number of species including compartments in the Ulu Muda Forest subs tantial number of rare and endemic species Resrve, Baling, Kedah. Paper presented in captured from the study site clearly indicate Bengkel I, Kajian Kesan Pembalakan that the hill dipterocap forest of Ulu Muda, Terhadap Waduk di Hutan Simpan Ulu Kedah harbours a rich assemblage of plant Muda, Baling, Kedah. Johor: UTM. diversity. This was further supported by [8]Ashton, P.S.1964. Ecological studies in the species accumulation curves with no tendency mixed dipterocarps forests of Brunei State. of flatten out. The generalization of the study Oxford Forest Memoire, No. 25. Oxford: results will depend largely on the similar type Oxford University Press. of upland forest ecosystem with distinct [9]Whitmore, T.C. 1990. An introduction to affinity to habitats. However, larger samples tropical rain forests. Oxford: Clarendon over varieties of sites with appropriate Press. statistical precision may be needed. In this [10]Basnet, K. 1992. Effect of topography on regard, it is not always possible to ensure that the pattern of trees in Tabonuco sample sizes are equal. (Dacryodes excelsa) dominated rain forest Hence, choosing diversity indices that are of Puerto Rico. Biotropica 24(1): 31-42. not most affected by the sample size is the [11]Philip, M.S.1994. Measuring trees and most appropriate for comparison of species Forests. Second edition. CAB richness and diversity particularly when the International. sample differs from one habitat to another. [12]Magurran, A.E. 1988. Ecological Diversity However, the information generated in this and Its Measurement. New York: study based on the present sampling design Chapman and Hall Publishers. and using various measures of diversity, is [13]Minitab Inc. 1994. Minitab User’s Guide. comparable with other studies. Release 10 for Windows. [14]Niiyama, K., Abd. Rahman, K., Iida, S., References: Kimura, K., Azizi, R. & Appanah, S. 1999. [1]Connel, J.H. 1978. Diversity in tropical rain Spatial patterns of common tree species forests and coral reefs. Science 199: 1302- relating to topography, canopy gaps and 1310. understorey vegetation in a hill dipterocarp [2] Brown, N.D.1990.Dipterocarp regeneration forest at Semangkok Forest Reserve, in tropical rain forest gaps of different Peninsular Malaysia. J. Trop. For. Sci. 11 sizes. DPhil Thesis. University of Oxford. (4): 731-745 [3] Saiful, I. 2002. Effects of selective logging [15]Pielou, E.C. 1969. An Introduction to on tree species diversity, stand structure Mathematical Ecology. New York: Wiley and physical environment of tropical hill Publishers. dipterocarp forest of Peninsular Malaysia. [16]Rennolls, K. & Laumonier, Y. 2000. Ph.D.Thesis. Universiti Kebangsaan Species diversity structure analysis at two Malaysia, Bangi, Selangor. sites in the tropical rain forest of Sumatra. [4]Gillison, A.N. & Brewer, K.R.W. 1985. The J. Trop. Ecol. 16:253-270. use of gradient directed transects or [17]Whitmore, T.C. 1984. Tropical rain gradsects in national resource survey. forests of the Far East, (2nd edn.) Oxford: Journal of Environmental management Clarendon Press. 20:103-127. [18]Ashton, P.S.1976. Mixed dipterocarp [5]Kent, M. & Coker, P. 1992. Vegetation forest and its variation with habitat in the description and analysis: a practical Malayan lowlands: a re-evaluation of approach. London: John Wiley and Sons Pasoh. Malayan Forester 39: 56-7. Ltd. [19]Davies, J. & Becker, P. 1996. Floristic [6]RRIM, 1988. Training manual on soil, composition and stand structure of mixed management of soils and nutrition of dipterocarp forest and heath forests in Hevea. Rubber Research Institute Brunei Darussalam. J. Trop. For. Sci. 8 Malaysia. (4): 542-569.

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[20]Austin, M.P. & Greig-Smith, P. 1968. The application of quantitative methods to vegetation survey II. Some methodological problems of data from rain forest. J. Ecol. 56: 827-844. [21]Austin, M.P., Ashton, P.S. & Greig-Smith, P. 1972. The application of quantitative methods to vegetation survey. III: a re- examination of rain forest data from Brunei. J. Eco. 60 :305-24. [22]Poore, M.E.D. 1968. Studies in Malaysian rain forest. 1.: the forest on Triassic sediments in Jengka Forest Reserve. J. Ecol. 56: 143-96. [23]Condit, Condit, R., Hubbell, S.P., Lafrankie, J.V., Sukumar, R., Manokaran, N., Foster, R.B. & Ashton, P.S. 1996. Species–area and species–individual relationship for tropical trees: a comparison of three 50-ha plots. J. Ecol. 84: 549-562.

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