Ecological characteristics of freshwater swamp forest, Perak Tengah, Malaysia / Liliwirianis Nawi

Freshwater swamp forest has a distinctive floristic structure, covering a very limited area. The freshwater swamp forests are forests that are found in low lying areas inundated by rainwater and composed of species that occur in confined areas due fragmentation of their habitats, and this make the populations more vulnerable to extinction in the short term. This study aims to determine the ecological characteristics of a freshwater swamp forest at Perak Tengah. which are forest community structure, species diversity, soil properties, tree soil relationship, tree biomass and carbon stock. A total of 150 plots with quadrats of 20 m x 20 m each (totalling 6 ha) were established at selected freshwater swamp forest areas. All trees with diameter at breast height (DBH) of 10 cm and above were measured, collected and identified. Topsoil samples (0-30 cm) in each plot were collected and analysed for texture, pH, base cations and available nutrients that include Mg, P, K. A total of 3364 tree stands belonging to 624 species in 184 genera and 56 families were enumerated in all study plots. Euphorbiaceae was the largest family recorded from the study plot. Density-wise, Euphorbiaceae also recorded as the highest tree density (≥10 cm DBH). Total tree basal area (BA) for all plots was 25.29 m2/ha. Macaranga triloba (Euphorbiaceae) was the most important species with the highest value for Species Importance Value Index (SIvi) of 11.52%. Euphorbiaceae, Dipterocarpaceae and Moraceae were the most important families. The Margalef’s Diversity Index index shows that the study area displayed high value of species richness. Shannon Diversity indicated high value of H’= 5.242 (Hmax=6.436). The Chave equation was applied to identify the total above-ground biomass (AGB) and Niiyama regression for the below-ground biomass (BGB). The total tree biomass was 472.743 t/ha, which was composed of AGB of 421.668 t/ha and BGB of 51.140 t/ha. The total amount of carbon stock was 222.189 t/ha. The freshwater swamp forest at Perak Tengah exhibited the presence of endemic and threatened species that are listed under the IUCN Red List, that include Dipterocarpus semivestitus, Shorea hemsleyana ssp. hemsleyana, S. macrantha, Vatica flavida and Hopea apiculata. Soil analyses showed that soil texture is varied, of which the soil texture was dominated by sandy clay loam. In general, ordinations using Canonical Correspondence Analysis (CCA) indicated that soil factors have no relationship with species distribution (eigenvalues for the three ordination axes p-value = 0.5860 at p˂0.05). The results gathered from this study are anticipated to contribute a new knowledge for the stakeholders on the importance of conservation of freshwater swamp forests and the species.