Carrying capacity for tree biomass of a subtropical mangrove along a
river in Japan inferred from forest structural features.
A subtropical mangrove along the Miyara River in Ishigaki Island, Japan
was studied for evaluating the carrying capacity for biomass of the
monospecific stands. Rhizophora stylosa and Bruguiera gymnorrhiza were
dominant in the downstream area whereas B. gymnorrhiza in the upstream.
The stem diameter D, stem height H, fine roots mass were measured and,
aboveground biomass AGB, belowground coarse root biomass BGBcoarse were
estimated. The AGB, BGBcoarse and fine root mass were estimated as
128.46 Mg ha-1, 31.01 Mg ha-1 and 12.75 Mg ha-1 in the R. stylosa;
269.82 Mg ha-1, 93.68 Mg ha-1 and 11.13 Mg ha-1 in the downstream B.
gymnorrhiza; and, 227.94 Mg ha-1, 81.05 Mg ha-1 and 6.35 Mg ha-1 in the
upstream B. gymnorrhiza plots, respectively. The AGB did not differ
among the plots, meanwhile BGBcoarse was significantly lower and fine
root mass was significantly higher in the R. stylosa plots than in the
downstream B. gymnorrhiza plots. Significantly lower mean individual
phytomass wt specific to tree density of R. stylosa plots than B.
gymnorrhiza plots in the – wt relationship was found, which denoted
the lower carrying capacity for AGB of R. stylosa than that of B.
gymnorrhiza. The results rejected our hypothesis that the stressful
edaphic conditions, such as high soil salinity and low pH at the
downstream, limit biomass and potential canopy height Hmax of mangrove
along a river gradient but partly supported another hypothesis that
biomass and Hmax differs between different mangrove species at the same