Assessment of species diversity, biomass and carbon stock between intact and naturally regenerated mangrove forest in Klang, Selangor

Abstract

Mangrove forest plays an important role as an ecosystem that provides ecosystem services and connectivity to the coastal environment, especially the need for capacity and storage of carbon reservoirs above and belowground that contribute to mitigating climate change. Understanding the biophysical characteristics of mangrove forests is very important in providing adequate information for management and conservation purposes. Therefore, this study aims to evaluate the structure of forest stands, biomass, and carbon stocks and to compare between intact mangrove forests and naturally regenerated mangrove forests. A total of 30 circular with 7-metre plots were successfully established in four mangrove forest reserves in Klang, Selangor, namely Kapar Forest Reserve (KFR), Telok Gedong Forest Reserve (TGFR), Telok Gedong Tambahan Forest Reserve (TGTFR), and Klang Island Forest Reserve (PKFR) with different stand ages of naturally regenerated mangrove forests (5, 8, 10, and 30-year-old). A total of 620 individual trees were measured in four study areas; 293 individuals in intact mangrove forest and 327 individuals in naturally regenerated mangrove forest. A total of 12 mangrove species from four families were found at four study sites. The results found that the intact mangrove forest in the PKFR had the highest density of 2,685 trees ha-1, whereas the TGFR with a 10-year-old stand had the highest density of 2,202 trees ha-1 in naturally regenerated mangrove forest. The highest total basal area of mangrove stand was recorded in the intact plots, ranging from (18.63 and 31.26 m2 ha-1) and lower in younger age stands (7.25 and 21.39 m2 ha-1). Rhizophora mucronata, Rhizophora apiculata, and Bruguiera parviflora species are the dominant species and were frequently encountered in intact mangrove forest, where they had an importance value index (IVI) of 141.43, 117.55, and 91.61, respectively. While Avicennia marina and Avicennia officinalis are the dominant species found in the naturally regenerated mangrove forest with an (IVI) value of 178.87 and 162.40, respectively. The mean value of aboveground and belowground in intact mangrove forest was highest in KFR (330.64 ± 135.29 Mg ha-1), while naturally regenerated mangrove forest in PKFR with a stand age of 30-years old showed the higher mean value of aboveground and belowground (238.69 ± 138.99 Mg ha-1), respectively. Huge quantities of biomass were estimated in those plots, especially in aboveground tree components with larger tree diameter and high species density, hence contributing to the highest total biomass of the whole study. The soil carbon stock shows the highest amount of carbon measured in intact mangrove forest, ranging from 422.89 Mg C ha-1 and 553.33 Mg C ha-1, whereas the soil carbon storage in naturally regenerated forest ranged from 136.34 Mg C ha-1 and 532.77 Mg C ha-1, respectively. Intact forest shows the highest soil carbon storage in general. As for the whole, among the intact mangrove forest, the highest values of carbon stock were observed in the TGTFR (678.94 Mg C ha-1) followed by KFR (610.05 Mg C ha-1), PKFR (597.2 Mg C ha-1) and TGFR (485.34 Mg C ha-1). TGTFR with 5-year-old stand age (630.174 Mg C ha-1) was found highest in naturally regenerated mangrove forest, followed by TGFR (10-year-old) (552.16 Mg C ha-1), KFR (30-year-old) (401.62 Mg C ha-1) and PKFR (8-year-old) (194.88 Mg C ha-1). Present study provides a comprehensive analysis to examine on how stand dynamics change over time, thus information on the current status of the stand, biomass, above-ground structure, below-ground carbon and nutrients within different mangrove forest types in Klang, Selangor will benefit relevant government agencies for mangrove forest management especially in planning for future monitoring as well as restoration.