3.3. Aboveground carbon stock
There was a significant variation in aboveground carbon stock
among the forest types (F(1,8) = 15.4; p < 0.001) (Table 3). With
345.0 ± 54.4 tons per ha, the disturbed primary forest had significantly
more aboveground carbon stock than all other forest types.
Mixed indigenous plantation forest had significantly more aboveground
carbon stock (240.3 ± 23.3 tons per ha) than all secondary
and plantation forest types (F(1,7) = 10.6; p < 0.001). Old-growth
secondary forest stands had significantly more aboveground carbon
stock (195.8 ± 36.8 tons per ha) than middle-aged and young
secondary forests, and all monoculture plantation forests
(F(1,6) = 9.51; p < 0.001). The aboveground carbon stock of B. javanica
and M. eminii monoculture plantations was comparable, but
significantly more than that of middle-aged and young secondary
forests, and C. lusitanica and P. patula monoculture plantations
(Table 3).
Forest stands with relatively larger basal area tended to have
significantly more aboveground carbon stock. This was the case
with old-growth forest stands, such as the disturbed primary forest,
mixed indigenous plantation and old-growth secondary forest
(Table 3). Since, the variation was partly attributable to differences
in stand age, analysis of covariance indicated that only the mixed
indigenous plantation would register significantly more aboveground
carbon stock (F(1,8) = 2.35; p = 0.037) if all the forest types
were of the same stand age (Table 3).