Altitudinal analyses of limestone vegetation at gunung api, Gunung Mulu National Park, Miri, Sarawak

Julaihi, bin Abdullah @ Lai, Chau Jian (2004) Altitudinal analyses of limestone vegetation at gunung api, Gunung Mulu National Park, Miri, Sarawak. Masters thesis, Universiti Malaysia Sarawak, (UNIMAS).

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Abstract

The study on floristic composition, total above ground biomass and species dominance of trees with d. b. h. >_5 cm and ground flora was conducted at 100 in intervals from 130 in to 1130 m a. s. l. at Gunung Api, Gunung Mulu National Park, Sarawak. A total of 419 species belonging to 243 genera and 93 families were recorded. Of these total, 1103 trees with d. b. h. ?5 cm were enumerated in an accumulative area of 1.04 ha, belonging to 195 species from 108 genera and 45 families. The ground flora has higher diversity in which 4953 individuals were enumerated in an accumulative area of 0.28 ha consisting of 340 species from 211 genera and 84 families. The mean density of trees with d. b. h. >_5 cm is 940 trees ha' with a total above ground biomass of 264 ton ha-', basal area (BA) of 31.37 m2 ha-' and leaf area index (LAI) of 3.93 ha ha-1. Within all studied plots, Euphorbiaceae has the most number of trees recorded followed by Dipterocarpaceae and Myrtaceae. Hopea andersonii is the most dominant tree species with importance value (IV) of 20.49, relative density (Rd) of 5.17, relative frequency (Rf) of 4.28 and relative basal coverage (RD) of 11.05. This is followed by Brownlowia glabrata (IV = 14.07) and Cleistanthus myrianthus (IV = 13.89). Plots at 130 in are the most diverse with 43 species, 37 genera and 25 families whereas plots at 330 in were recorded with the most number of trees. 79.06% of the trees enumerated are having d. b. h. of below 20 cm. The total above ground biomass of trees with d. b. h. >_5 cm decreases as altitude increases. For ground flora, Rubiaceae is the most common diverse family, followed by Euphorbiaceae and Orchidaceae. The most dominant species of ground flora are seedlings of Cleistanthus myrianthus with summed dominance ratio (SRD) of 3.01, followed by Hopea cernua (2.98) and the herb Elastostema variolaminosum (2.63). The total above ground biomass of ground flora is 22.32 ton ha"'. Forty one (41) species (9.79%) of the total flora enumerated are endemic to limestone forest in Sarawak. Eight species enumerated in Gunung Api are very rare species as they are recorded only once in a single location. One hundred and thirteen (113) new records in limestone forest in Sarawak were identified. The characteristics of soils and their influence on biomass and floristic composition at every altitudinal level were also discussed. Results of the study show that limestone forest of Gunung Api is indeed very rich in species and many species are confined to limestone habitats. The result also showed that pH, nitrogen, calcium and magnesium are highly correlated with altitude

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