TOC and organic matter contents of mangrove sediments
The TOC content obviously decreased from surface to bottom of
the sediment cores (ANOVA, p b 0.0001, Table 5, Fig. 2). The TOC
content of sediments in the fringe forest was significantly lower than
that of sediments in the transitional (p= 0.025) and the interior forests
(p= 0.002). The TOC content of sediments in the transitional forestwas
similar to that of sediments in the interior forest (p = 0.679). The organic
matter content (OM) ranged from 2.9 to 20.2%, with an average
of 7.8±2.9% (Fig. 3). The TOC contentwas positively correlatedwith organic
matter content by the following linear regressionmodel (Eq. (2))
(Fig. 3):
TOC % ð Þ¼ 0:227 OM % ð Þþ 0:244 R2 ¼ 0:56; p b 0:0001; n ¼ 225:
ð2Þ
The TOC content and the bulk sediment density had an inverse relationship,
whichwas described by the following non-linear least-squares
regression model (Eq. (3)) (Fig. 4):
Bulk sediment density ¼ 1:539eð−0:289TOCÞ R2 ¼ 0:62; p b 0:001; n ¼ 225:
ð3Þ
3.3. Above-ground C stock estimates
Themean living tree C pool increased from the fringe toward the interior
forest (ANOVA, p b 0.05), and accounted for a significant proportion
of the above-ground C stock (Fig. 5). The remaining contribution from
dead tree and downed woody debris C pool was a small proportion
(b4%), and tended to increase from the fringe toward the interior forest
(ANOVA, p b 0.05; Fig. 5). The mean above-ground C stock overall had