Species composition and diversity of understorey vegetation at Pelagat forest reserve, Besut, Terengganu, peninsular Malaysia

This study was conducted to determine the species composition and diversity of understorey vegetation in the Pelagat Forest Reserve, Besut, Terengganu. A total of 10 quadrats, each measuring 2 m × 2 m (0.004 ha), were established to assess seedlings with heights ≥ 15 cm up to 1.5 m, and quadrats of 5 m × 5 m (0.025 ha) were set up to assess saplings with a diameter at breast height (DBH) < 5 cm but with a height ≥ 1.5 m. The results showed that a total of 116 individual trees were identified, consisting of 49 individuals belonging to 20 families, 29 genera, and 33 species for the seedling category, while 67 individuals comprising 26 families, 43 genera, and 51 species were recorded for the sapling category. The total density of seedlings and saplings was 12,225 individuals/ha and 2,680 individuals/ha, respectively, with Myrsinaceae contributing the highest seedling family density at 2,250 individuals/ha, while Rubiaceae contributed the highest sapling family density at 440 individuals/ha. At the species level, Ardisiasp.1 recorded the highest seedling density with 1,750 individuals/ha, while Pentace curtisii, Rubroshorea ovalis, and Saprosma glomerulatawere the highest contributors to sapling density, with 120 individuals/ha each. The Shannon Index (H) values were 3.30 and 3.85 for seedlings and saplings, respectively, while the Shannon Evenness Index (E) values were 0.94 and 0.98 for seedlings and saplings, respectively. The Margalef Richness Index (DMG) values were 8.22 and 11.89 for seedlings and saplings, respectively. A total of eight species endemic to Peninsular Malaysia were recorded in this study, comprising eight families, eight genera, and 10 individuals.