Assessment of Floristic Composition of Kilim Geoforest Park, Langkawi, Malaysia

The present study was carried out to analyze the species diversity and quantitative analysis of mangrove forest in three riverine ecosystems at River Kisap, River Ayer Hangat and River Kilim at Kilim Geoforest Park. One hundred plots, each of size 20 m × 20 m, were established at a distance of 250 m apart along the three rivers. Every existing species that occurred within the plot and trees of diameter at breast height of 1 cm and above were enumerated and identified. The data were analyzed for species richness, diversity and evenness. The species richness were computed based on the Jacknife method, species diversity index were calculated using Simpson’s Index, Shannon-Wiener Index and Brillouin’s Index. The evenness indexes were measured by Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness. A total of 11488 individual trees representing 58 species, 39 genus, and 23 families were recorded. The most abundant species was Rhizophora apiculata (3449) and Ceriops tagal (2060). The diversity results show that Shannon-Wiener, Simpson’s index of diversity and Brillouin index was high (2.0 to 3.0), (0.7 to 0.8), to (2.0 to 3.0) respectively and the evenness index however was low (0.1 to 0.2).


Introduction
Langkawi is an archipelago of 104 islands situated at 6°21'N; 99°48'E to the north of the Straits of Malacca. The total area is about 47,848 ha. The topography of Langkawi is mainly flat to mountainous, rising up to 881 meter height, which is the highest peak at Gunung Raya. Langkawi Geoforest Park comprising all of the 99 islands and the total land area of Kilim Geoforest Park is about 478 square kilometers comprises of three main river basins i.e. River Kilim, River Ayer Hangat and River Kisap. Kilim Geoforest Park experiences dry season lasting two to three months between December and March, which may influences the flora to have an affinity to those happened in Burma and Thailand. The ecosystems of the old limestone rock formation, the caves, the mudflats and the seas that surround it have three main types of vegetation i.e. the mangroves, the vegetation of the limestone hills and the flora of the mudflats and beaches.
Mangroves are defined as plants, shrubs, palms and ferns that are growing within the inter-tidal region of coastal and estuarine environments in the tropics and subtropics. The important of mangroves in the world was given by Tomlinsons (1986). Mangrove areas in Langkawi cover approximately 3142 ha (JPSM, 2003) and the largest area is at the Kisap Forest Reserve with 1336 ha of mangrove forest. Mangroves of Langkawi are considered as unique and rare occurrence, in the sense that they are found on shallow limestone substratum areas. Japar (1994) reported that Malaysia has 38 exclusive, 57 non-exclusive and more than 10 associated mangrove biota. Thus, this data proved Malaysia as one of the diverse mangrove population in the world.
Mangrove forest promotes a unique root system with a physiology of the plant species that are capable of preventing soil erosion and cleaning water contaminated with metallic pollutants (Norhayati & Latiff, 2001). The mangrove also serves as breeding grounds to many species of fishes, prawn and other sea life. The mangrove vegetation in this area is quite diverse and includes many important species; some with medicinal properties. The limestone hills of the area have a rich diversity of species of ornamental plants such as the cycads and orchids, the limestone rocks also support many bryophytic flora, lichens and macro fungi (Norhayati & Latiff, 2001). Nowadays, shorelines are one of the most rapidly changing areas on the Earth. Based on literitures as many as 3 billion people inhibit within 60 km of a shoreline areas (Woodroffe, 2002). Because of this huge populations that inhabit in the areas near the coast to take benefit of valuable marine resources and also to participate in seaborne Since the mangrove forests of Langkawi especially at Kilim Geoforest Park areas are facing impacts from increasing of boat traffic, coastal development such as reclamation, erosion, accretion and sedimentation, which are mostly for ecotourism activities. Hence, the objective of this study is to assess floristic composition and diversity of Kilim Geoforest Park. This study is necessary to begin conservation assessment that will provide baseline ecological data for sustainable management of the mangrove forest in Malaysia.

Description of study area
The study area is situated between latitude of 6 o 29 ' 33.20'' to 6 o 23' 6.24'' North and between longitude 99 o 48' 0.34'' to 99 o 55' 30.86'' East at the northeast of Langkawi Island within the state of Kedah, Malaysian. The study area was divided into three study sites i.e. River Kisap, River Kilim and River Ayer Hangat of Kilim Geoforest Park. These three riverine were rich with mangrove forest, flourished on limestone formation, which is a rare occurrence. The topography varies from flat coastal plains, hilly areas to rugged mountains.

Methods
The field survey for the ecological study was conducted in November 2009 until February 2010. The study areas were visited three times during the study periods. In this study, a total of 100 study plots of about 20 m × 20 m quadrats (400 sq m) size were established. About 40 plots were placed at the elevation 6.4 m a.s.l and the intervals of 250 m along River Kilim and 30 study plots along River Kisap and River Ayer Hangat each. Data were gathered from each quadrate. All the trees in the plot with diameter at breast height (DBH) >1cm were enumerated, measured and identified. Other parameters recorded were species name and height (HT). In this study, the specimens, both mangrove and non-mangroves, were collected, placed in transparent plastic bag and labeled properly. They were then brought back to the laboratory in Faculty of Forestry of University Putra Malaysia. Samples were preserved as Herbaria and a few of them were dissected to identify the specimens. They were identified using the mangrove identification manuals and standard Floras (Ng & Sivasothi, 1999;Ng 1978;1989;Whitmore, 1972;1973). The specimens whose identity could not be confirmed were sent to experts for further identification and verification. Precise GPS locations were recorded from all the field areas visited.

Quantitative analysis
Important quantitative analysis such as density, frequency and abundance of tree species and non trees species were calculated based on the method that was suggested by Curtis and McIntosh, (1950).

Density
Density is an expression of the numerical strength of a species where the total number of individuals of each species in all quadrats is divided by the total number of quadrats studied.

Density = Total number of individuals of a species in all quadrats
Total number of quadrats studied

Frequency (%)
This refers to the degree of dispersion of individual species in an area and expressed in terms of percentage occurrence.
Frequency (%) = Number of quadrats in which the species occurred × 100 Total number of quadrats studied Abundance Referring to the number of individuals of different species in the community per unit area.

Abundance = Total number of individuals of a species in all quadrats
Total number of quadrats in which the species occurred

Important Value Index
This index is used to determine the overall importance of each species in the community structure. To calculate this index, the percentage values of the relative frequency, relative density and relative dominance are summed up together and designated as Important Value Index (IVI) of the species (Curtis, 1959).

Main Floristic Attributes and Dominance
A total of 11488 individual were recorded from the three locations i.e. River Kisap, River Ayer Hangat and River Kilim. These trees belonged to 23 families, 39 genus and 58 species (Table I and II). Avicenniaceae, Rhizophoraceae, Moraceae, Lythraceae, Polygalaceae and Meliaceae were distributed in most study areas. However, Ebenaceae and Euphorbiaceae were appeared at least in two different locations in this study. On the other hand the rest of the family were appeared only in one location.

Mangrove Composition and Dominance
For mangrove composition assessment, a total of 11148 trees were recorded in 100 study plots belonged to 4 families, 7 genera and 12 species (Table III and IV). Among the families in the plot, Rhizophoraceae was the most diverse with 3 genera and eight species respectively. This result is not surprising since this family is the largest family of mangrove trees in Malaysia. (Note 2) Rhizophoraceae accupied 80.37% of total population which is the most diverse family in the study areas. This was followed by Avicenniaceae, Euphorbiaceae and Meliaceae; 18.58%, 1.01 % and 0.04%, respectively. Interestingly, mostly mangrove species such as Rhizophora apiculata, Rhizophora mucronata, Xylocarpus granatum and Ceriops tagal were found distributed fairly in all study areas. These species of mangrove were also identified as dominance species in the study area. On the other hand, 5 mangrove species such as Xylocarpus rumphii and Ceriops decandra were only appeared in River Ayer Hangat and River Kisap, respectively. Similar situation was observed on Avicennia officinalis, Bruguiera gymnorrhiza and Bruguiera sexangula, where they only recorded in River Kilim.

Important Species and Species Diversity
Data on important species of Kilim Geopark Langkawi were summarized in Table V and VI. In the study area, eight species of true and associate mangroves were identified as the most important species, they were Rhizophora apiculata, Ceriops tagal, Xylocarpus granatum, Rhizophora mucronata, Brugueira cylindrica, Brugueira parviflora, Bruguiera sexangula and Avicennia marina with their IVI values were 87. 55, 45.55, 40.45, 30.28, 22.60, 22.12, 11.29 and 7.79, respectively. These species were also high in terms of density per hectare and frequency.

(Note 3)
Rhizophora apiculata, Rhizophora mucronata, Ceriops tagal, Xylocarpus granatum and Brugueira parviflora were the important species of mangrove trees in River Ayer Hangat, River Kilim and River Kisap. These species of mangrove trees life abundantly in those areas make up of more than 50% of total population. On the other hand, Avicennia marina, Avicennia officinalis and Brugueira cylindrica were only important in selected areas. For instance, Avicennia marina were only appeared at River Ayer Hangat and River Kisap. Avicennia officinalis and Bruguiera cylindrica were only recorded in River Kilim and River Kisap, respectively.
In terms of family value index (FVI), Rhizophoraceae was the most important mangrove family in the Kilim Geopark with FVI value of 224.77 (Table VII). This was followed by Meliaceae and Avicenniaceae with FVI values of 46.84 and 10.66, respectively. On the other hand, aassociate mangrove family were exhibited in a small population in the study areas.
(Note 4) For species diversity study, three parameters were used namely species richness, heterogeneity and evenness (Table VIII). According to Jackknife index, River Kisap (62.9) was the richest area with mangrove species in the Kilim Geopark as compared to River Ayer Hangat (25.7) and River Kilim (24.7). River Kisap contain 15 unique mangrove species.
For species heterogeneity assessment, Simpson's index, Shannon-Wiener index and Brillouin index were used in this study. All index showed that River Kisap was the most diverse area in Kilim Geopark and followed by River Kilim and River Ayer Hangat. River Kilim has the most evenness index in the Kilim Geopark and followed by River Ayer Hangat and River Kisap.

Discussion and Conclusion
Langkawi Geoforest Park is positioned as an archipelago of 99 islands. In 2007, it was awarded the Geopark status by the United Nations Educational, Scientific and Cultural Organisation (Unesco) for its geological history dating back some 500 million over years. Hence, the findings of this study were very important in order to conserve this world heritage area, in terms of management of mangrove diversity. Based on our findings, Rhizophora apiculata and Rhizophora mucronata were two dominant species in the Kilim Geopark. Our findings are parallel with the previous study conducted by Norhayati and Latiff (2001)  and Aegiceras corniculatum and most of the species were also reported in our study. This is proved that main important mangrove species were still present intact in the study areas and their existent must be protected and managed properly for our future generation.
According to Curtis and McIntosh (1951), if the IVI is more than 10, it shows that the species is dominant to that area. In our findings showed that Kilim Geoforest Park mangrove forest can be considered as Rhizophora-Ceriops zone. The diversity estimated using Shannon-Wiener, Simpson's index of diversity and Brillouin index was high and the evenness index however was low (0.1 to 0.2). The Smith and Wilson's index of evenness is more preferred compared the others because it is independent of species richness and sensitive to both and rare common species (Krebbs, 1999).
The reduction of mangrove forests have been observed in most states in the Peninsular of Malaysia (Latiff, 2004). Inspite of their immense role in protecting human resource and biodiversity, these unique mangrove forest have been facing tremendous threats such as exploitation of mangrove resources for multiple uses such as fodder, fuel wood, timber for building material, alcohol, paper, charcoal and medicine (Upadhyay et al. 2002). Apart from those, conversion of forest areas to aquaculture and agriculture sites, construction of port and harbour, extension of human inhabitation, over-grazing, urbanization, industrialization and pollution are major common occurrences that dwindle mangrove forest in the world (Blasco & Aizpuru 1997;Naskar 2004;Upadhyay et al. 2002). In Langkawi itself, uncontroll land development extivities such as development of Langkawi cable car as well as tourism arrivals to Langkawi up to 1.88 million people every year may threaten natural environment of the study areas in the long run. Steps have been taken by Forestry Department to conserve some of mangrove forests as forest reserve area such as Kisap Forest Reserve.