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EC 09
VEGETATIONAL STRUCTURE AND COMPOSITION IN PULOKERTO ISLAND,
MUSI RIVER-PALEMBANG, SOUTH SUMATRA
Indra Yustian dan Hilda Zulkifli
Department of Biology, Faculty of Science, University of Sriwijaya
Email: indra.yustian@gmail.com, Mobile: 081271260812
ABSTRACT
Vegetation covering an area has a definite structure and composition developed as a result of long term interaction with biotic and abiotic factors, and any change in the status of these factors will disturbs the floristic composition of the environment. Five quadrates each in six line-transects, or total 30 quadrates, with sampling size of 20x20 m2 for trees, 10x10 m2 for poles, 5x5 m2 for sapling and 2x2 m2 for seedlings was selected for analysis of vegetation to quantify the composition and dominance of the species. The highest Importance Value Index (IVI) for tree species was that of Lagerstroemia speciosa (89.45) followed by Gluta renghas (64.53) and Mangifera indica (22.48) For poles, the highest IVI values was also Lagerstroemia speciosa (106.04), followed by Psidium guajava (32.20) and unidentified species #17 (28.04). In saplings stage, Mimosa vigra (177.11) has the highest IVI, followed by Strobilanthus sp. (50.13) and Lagerstroemia speciosa (14.28). For seedlings, the highest IVI values was that of Micania mucronata (90.26), followed by Centrosoma sp (33.38) and Mimosa vigra (31.93). Lagerstroemia speciosa, Gluta renghas and Mimosa vigra were found to be the most dominant species in the study area.
Key words: Vegetation Analysis, Pulokerto, Agropolitan ecosystem, Importance Value Index
INTRODUCTION
Forest and vegetation of particular ecosystem generally influenced by the external factors especially the man made development activities. For a long time it was believed by some ecologists like Clements (1916), Braun-Blanquet (1932) and Odum (1971), that vegetation is composed of certain distinct and fairly discrete plant communities. This view regards communities as having a degree of internal organization which jointly modifies the environment with sharp delimitation from other communities (Odum, 1971). The composition of plant structures is closely associated with the biotic and abiotic environmental factors which make sudden changes due to external factors of disturbances.
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MATERIAL AND METHODS Study Area
The study area is located between 3º01' 47”-3º 02’26” south longitudes and 104º3λ'13” -104º40'14 east latitudes, in the Musi River, Gandus Subdistrict in Palembang (Figure 1). The area has an extent area of about 112 ha with elevation ranging only 2-4 m asl. The area located in the upstream of Palembang city and could function as the water-catchments area. The Pulokerto Island has a permanently flooded swamp ecosystem (37.36%) and seasonally flooded (14.88%).
According to Palembang law no. 23/2000, Pulokerto island region has been established as the region of agro-ecosystem. The highest rainfall usually in October of 469 mm and the lowest was in July, amounting to 77 mm (Bappeda, 2009). The temperature average was 23,40C – 31,70C.
Figure 1. Aerial view of Pulokerto Island, Musi River, Palembang
METHODS
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Table1. Composition and Importance Value Index of the species in the sampling area of Pulokerto
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Vegetation Structure
Table 1 also depicts the highest Importance Value Index (IVI) for each species found. The highest IVI For tree species was that of Lagerstroemia speciosa (89.45) followed by Gluta renghas
(64.53) and Mangifera indica (22.48). The high value of Lagerstroemia speciosa and Gluta renghas
because both species are resistant to conditions that most of the study area were flooded permanently or seasonally. This species also did not experience significant disruption due to human activities, such as felled for timber. Although the Gluta renghas was traditionally often used as base material boat building, the individuals’ species present are left for not having a good form or volume to be made boats (personal observation).
The high value of Lagerstroemia speciosa applies also in poles stage. The highest IVI values for poles was also Lagerstroemia speciosa (106.04), followed by Psidium guajava (32.20) and unidentified species #17 (28.04). Lagerstroemia speciosa is also one of the highest IVI in sapling stage. This condition indicates that the species are able to adapt and regenerate well in flooded swampy area such Pulokerto island.
In saplings stage, Mimosa vigra (177.11) has the highest IVI, followed by Strobilanthus sp.
(50.13) and Lagerstroemia speciosa (14.28). Mimosa and Strobilanthus are not tree. They will never become a tree. The high value of Mimosa and Strobilanthus indicated that the area of the study often susceptible to interference in the form of flooded.
For seedlings, the highest IVI value was that of Micania mucronata (90.26), followed by
Centrosoma sp (33.38) and Mimosa vigra (31.93).
Based on the IVI value, Lagerstroemia speciosa, Gluta renghas and Mimosa vigra were found to be the most dominant species in the study area. These species were found almost throughout the plots and transects of observations, with a plenty number of individuals and have a basal area or canopy which is relatively large compared to other species.
Although the vegetation existed in several stages, there was a reduced number of small tree individuals (<10 cm) which may be attributed to recurrent disturbances (marginal land encroachment, grazing, flooded and firewood collection). Better management for the allotment plan as agro-ecosystem and protection of regenerated species and additional plantation in disturbed areas surrounding and local control over the island is therefore urgently needed.
CONCLUSION
Forty-eight species were recorded within the six line-transects. Lagerstroemia speciosa, Gluta renghas and Mimosa vigra were found to be the most dominant species in the study area.
ACKNOWLEDGEMENT
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REFERENCES
Bappeda. 2009. Masterplan Kawasan Agropolitan Gandus. Palembang
Braun-Blanquet J (1932). Plant Sociology: The study of plant communities. New York, McGraw-Hill, 439 p.
Clements FE (1916). Plant Succession: An Analysis of the Development of Vegetation. Washington, D.C., Carnegie Institute, 388 p.; Publication No. 290.
Mueller-Dombois D and Ellenberg H (1974). Aims and Methods of Vegetation Ecology. New York: John Wiley and Sons. 547 p
Odum EP (1971). Fundamentals of Ecology, 3rd ed. Philadelphia: Saunders. 574 p
