10 Carbon Stocks from Peat Swamp Forest and Oil Palm Plantation …
221
range of aboveground C stocks in other Indonesian primary peat swamp forests of
118–214 Mg C/ha (Table 10.5). Contrastingly, a peat swamp forest in Mexico had
lower aboveground C stocks (Adame et al. 2015). Although the peat swamp forest
in Mexico had two times higher tree density (2469 trees/ha) compared to this study,
the area was dominated by only a single species of Pachira aquatic (Adame et al.
2015).
Our analysis showed that aboveground carbon contributed about 10% to the total
ecosystem C stocks in the primary forests (Table 10.3) which is comparable to
results from previous studies in the tropics which reported that 10–13% of the total
ecosystem C stocks were allocated above ground (Draper et al. 2014; Murdiyarso
et al. 2009; Adame et al. 2015; Bhomia et al.2019). In areas where the peat is
deep, a smaller contribution of aboveground carbon to total ecosystem C stocks can
be expected. For example, Basuki (2017) reported that aboveground carbon only
contributed less than 4% to total ecosystem C stocks in West Kalimantan, Indonesia
where the peat thickness was more than 9 m and contained 3,800 Mg C/ha.
Globally, carbon stocks of recently established oil palm plantations 1–5-year old
fall between 1.3 and 16.2 Mg C/ha. The oil palm C vegetation stocks in this study
were comparable to that reported by Corley et al. (1971) for OP1, and Ng et al.
(1986) for OP3 and OP5. Our study reported aboveground carbon stocks from
young plantation, hence the estimates are lower than the average carbon stocks in
oil palm plantation over a full rotation cycle. The variation of oil palm C stocks
among studies may be related to differences in soil condition, management practices
(e.g., palm density and fertilizer application) (Syahrinuddin 2005; Henson 2003),
or sampling approaches (destructive or allometric). A review analysis from data of
aboveground carbon of oil palm plantations in Malaysia and Indonesia showed that
oil palm C stocks were strongly correlated with the age of the stands, which was best
explained by a power model (Oil palm C stocks = 3.4713 * age
0.8382 ; r
2
= 0.82). The
ecosystem C stocks in the final stage of oil palm plantations (798 Mg C/ha) were 45%
of total ecosystem in primary forests, suggesting that increasing of aboveground C
stocks over time is insignificant in oil palm plantations and will never compensate
the expense of AGB loss before forest conversion. the time-averaged aboveground
C managed by smallholder oil palm plantation is 37.76 Mg C/ha for one cycle in
Indonesia where almost half of above ground carbon stocks from oil palm plantation
in Peruvian Amazonia reported by Malaga et al (2020) (78.2 ± 2.0 Mg C/ha).
Conversion of peat swamp forest to oil palm plantations resulted in substantial
carbon losses to the atmosphere from changes in vegetation C stock. As hypothesized,
we found that the conversion of forest to oil palm plantations significantly reduced the
vegetation carbon by approximately 93% (Table 10.3 and Fig. 10.8). This was similar
to the conclusion of Basuki (2017) who also found more than 99% of plant carbon
reduction after conversion of primary forest on deep peats to oil palm plantation
in West Kalimantan, Indonesia. Our estimate was higher than the one by Kho and
Jepsen (2015), who reported about 81–88% of the plant C stocks were lost due to
forest conversion to oil palm plantations in Malaysia.
In a chronosequence scenario, the secondary forest in Tanjung Harapan had the
rapidly accumulate aboveground C stocks but not peat. It is important to point out
221
range of aboveground C stocks in other Indonesian primary peat swamp forests of
118–214 Mg C/ha (Table 10.5). Contrastingly, a peat swamp forest in Mexico had
lower aboveground C stocks (Adame et al. 2015). Although the peat swamp forest
in Mexico had two times higher tree density (2469 trees/ha) compared to this study,
the area was dominated by only a single species of Pachira aquatic (Adame et al.
2015).
Our analysis showed that aboveground carbon contributed about 10% to the total
ecosystem C stocks in the primary forests (Table 10.3) which is comparable to
results from previous studies in the tropics which reported that 10–13% of the total
ecosystem C stocks were allocated above ground (Draper et al. 2014; Murdiyarso
et al. 2009; Adame et al. 2015; Bhomia et al.2019). In areas where the peat is
deep, a smaller contribution of aboveground carbon to total ecosystem C stocks can
be expected. For example, Basuki (2017) reported that aboveground carbon only
contributed less than 4% to total ecosystem C stocks in West Kalimantan, Indonesia
where the peat thickness was more than 9 m and contained 3,800 Mg C/ha.
Globally, carbon stocks of recently established oil palm plantations 1–5-year old
fall between 1.3 and 16.2 Mg C/ha. The oil palm C vegetation stocks in this study
were comparable to that reported by Corley et al. (1971) for OP1, and Ng et al.
(1986) for OP3 and OP5. Our study reported aboveground carbon stocks from
young plantation, hence the estimates are lower than the average carbon stocks in
oil palm plantation over a full rotation cycle. The variation of oil palm C stocks
among studies may be related to differences in soil condition, management practices
(e.g., palm density and fertilizer application) (Syahrinuddin 2005; Henson 2003),
or sampling approaches (destructive or allometric). A review analysis from data of
aboveground carbon of oil palm plantations in Malaysia and Indonesia showed that
oil palm C stocks were strongly correlated with the age of the stands, which was best
explained by a power model (Oil palm C stocks = 3.4713 * age
0.8382 ; r
2
= 0.82). The
ecosystem C stocks in the final stage of oil palm plantations (798 Mg C/ha) were 45%
of total ecosystem in primary forests, suggesting that increasing of aboveground C
stocks over time is insignificant in oil palm plantations and will never compensate
the expense of AGB loss before forest conversion. the time-averaged aboveground
C managed by smallholder oil palm plantation is 37.76 Mg C/ha for one cycle in
Indonesia where almost half of above ground carbon stocks from oil palm plantation
in Peruvian Amazonia reported by Malaga et al (2020) (78.2 ± 2.0 Mg C/ha).
Conversion of peat swamp forest to oil palm plantations resulted in substantial
carbon losses to the atmosphere from changes in vegetation C stock. As hypothesized,
we found that the conversion of forest to oil palm plantations significantly reduced the
vegetation carbon by approximately 93% (Table 10.3 and Fig. 10.8). This was similar
to the conclusion of Basuki (2017) who also found more than 99% of plant carbon
reduction after conversion of primary forest on deep peats to oil palm plantation
in West Kalimantan, Indonesia. Our estimate was higher than the one by Kho and
Jepsen (2015), who reported about 81–88% of the plant C stocks were lost due to
forest conversion to oil palm plantations in Malaysia.
In a chronosequence scenario, the secondary forest in Tanjung Harapan had the
rapidly accumulate aboveground C stocks but not peat. It is important to point out