Population Structure, Allometry and Above-Ground Biomass of Avicennia marina Forest at the Chishui River Estuary, Tainan County, Taiwan

Abstract

This study investigates the structure and above-ground biomass of an Avicennia marina forest located at the mouth of the Chishui River, in Tainan County, Taiwan. Four mangrove stands with various characteristics and density were studied, including sea edge pioneer (Stand Tat the northern river bank) and young mangroves (Stands Ⅱ and Ⅲ at the northern river bank; Stand Ⅳ at the southern river bank). The tree heights of these four mangrove stands varied from 0.9 to 1.2 m, diameter at breast height (DBH) ranged from 2.4 to 5.1 cm, and tree density ranged from 5,029 to 17,000 trees ha^(-1). The distribution of DBH was skewed to small classes, and all sampled trees showed reverse J-shaped distributions, which suggested an active regeneration in these populations. The allometric relationships derived by regressions of leaves, stems, branches, and total above-ground biomass vs. DBH of A. marina trees, for each tree component were highly significant, with R^2 values from 0.750 to 0.956. Total above-ground biomass was estimated as a power function of the DBH as an independent variable, W(subscript T)-0.1012 (DBH^2) + 0.5402 (DBH)-1.5674, where W(subscript T)-above-ground biomass (kg). The allometrie relationship was used to estimate total above-ground biomass, which varied from 10.3 ton ha^(-1) for the pioneer stage (Stand Ⅰ, near the river mouth) to 22.7 ton ha^(-1) for a more mature mangrove at the upstream of the river, indicating that this A. marina forest at the Chishui River estuary mouth has less above-ground biomass than these forests elsewhere in the world.