The disturbance of mangrove forests could affect climate regulation, hydrological cycles, biodiversity, and many other unique ecological functions and services. Proper biomass estimation and carbon storage potential are needed to improve forest reference on biomass accumulation. The establishment of a site-specific allometric equation is crucial to avert destructive sampling in future biomass estimation. This study aimed to develop a site-specific allometric equation for biomass estimation of a mix-mature mangrove forest at Sungai Pulai Forest Reserve, Johor. A stratified line transect was set up and a total of 1000 standing trees encompassing seven mangrove tree species were inventoried. Destructive sampling was conducted using the selective random sampling method on 15 standing trees. Five allometric equations were derived by using diameter at breast height (D), stem height (H), and wood density (ρ) which were then compared to the common equation. Simulations of each allometric equation regarding species were performed on 1000 standing trees. Results showed that the single variable (D) equation provided an accurate estimation, which was slightly improved when incorporated with the H variable. Both D and H variables, however, gave inconsistent results for large-scale data and imbalance of sampled species. Meanwhile, the best fit either for small-scale or large-scale data, as well as for imbalanced sample species was achieved following the inclusion of the ρ variable when developing the equation. Hence, excluding the H variable while including the ρ variable should be considered as an important determinant in mixed mangrove species and uneven-aged stand for aboveground biomass estimation. This valuation can both improve and influence decision-making in forest development and conservation.

This study aimed to access different desirable characteristics of nine Hibiscus cannabinus L. accessions based on morphophysiological characteristics and fiber tensile strength for an effective selection of H. cannabinus plant improvement. Four China accessions (FH952, T15, T17, and T19), four Bangladesh accessions (HC2, HC95, V4202, and V4383), and V36 (control) accession were examined in a four-month cultivation period. The experimental design was arranged using randomized complete block design with three replications. Stem diameter was found to be significantly related (p ≤ 0.05) with all morphological and yield characteristics except for leaf dry weight and growth efficiency. Bigger stem diameter was an indicator of fiber yield in attempts to apply crossing and selection to improve performance. Photosynthesis rate also was found to be significantly related (p ≤ 0.05) with stomatal conductance, transpiration rate, instantaneous water use efficiency, and carboxylation efficiency. High photosynthesis rate could be an indicator to interpret the pattern of genetic variation of plant assimilation rate and its relation with environmental and agronomic factors. The fiber tensile modulus, however, was found to be inversely correlated with fiber diameter. The present study suggests the selection of control, V4383, HC2, and FH952 accessions for a breeding line as they possess high fiber yield, fiber strength, and photosynthetic efficiency.