prescribed fire, agricultural land preparation). The default values of emission factors
that can be used for tropical peatlands are: 464, 210, and 21 g kg for CO 2 –C, CO, and
CH 4 gases, respectively. However, there are still uncertainties about the relationship
between GHGs emission to biomass burning as only a few empirical based parameters of fuel loads and their combustion efficiency are currently reported in the
tropics. Huijnen et al. (2016) reported that in September and October 2015, when
widespread forest and peatland fires burned over large parts of Southeast Asia, a
large amount of terrestrially stored carbon was released into the atmosphere, primarily in the form of CO 2 , CO, and CH 4 . At the time, a mean emission rate of 11.3
Tg CO 2 per day was recorded. More studies are needed to complement existing data
toward achieving a reliable estimate of CO 2 emission from burning in drainage
tropical peatlands.
15.3.2 Rewetted Peatlands
In the “rewetted organic soils,” the net emission that occur are calculated based on
the net flux of CO 2 –C (emission or removal) from the rewetted organic soils and the
net flux of CH 4 –C (commonly emission) from the rewetted organic soils. CO 2 –C
(emission or removal) from the rewetted organic soils is the accumulation of CO 2 –C
emission/removal from the soils and non-tree vegetation (CO 2 –C composite ) and
off-site CO 2 –C emission from dissolved organic carbon exported from rewetted
organic soils (CO 2 –CDOC). For CO 2 –C composite emission in the tropics, since there
are no data available for rewetted organic soils, the emission factor can be assumed
to be zero. This value is based on observations of areas that are not drained so that it
reflects the fact that successful rewetting effectively reduces soil decomposition of
organic matter and stops oxidation of soil organic matter, and the decomposed
organic matter is not oxidized due to saturated conditions. Calculation of CO 2 –
CDOC emission in the tropics can use a default value of emission factor of 0.51 t
CO 2 –C ha
À1 year
À1 (IPCC 2014). CH 4 emission and uptake from “rewetted organic
soils” are generated from net CH 4 production-oxidation and CH 4 emission generated
by burning soil organic matter during fires. The probability of a fire occurring in the
“rewetted organic soils” is less likely to occur if the position of the water level
approaches the surface, but if there is a fire the resulting emission must be included
as well as the resulting N 2 O emission. The same approach for peat fires in the
drained peatlands is used. CH 4 emission resulting from organic soil decomposition
by microbes in anaerobic conditions in the “rewetted organic soils” in the tropics can
use a default value of emission factor of 41 kg CH 4 –C ha
À1 year
À1 (IPCC 2014).
N 2 O emission from “rewetted organic soils” are controlled by the amount of nitrogen
available for the nitrification and denitrification processes, as well as the availability
of oxygen needed for the chemical reaction. In tropical peatlands with saturated
condition, this can encourage denitrification and N 2 O consumption, but in practice
this effect is very small and is considered to be negligible.
15 Climate-Responsible Management of Tropical Peatlands: The Need for Integrated. . .
451
that can be used for tropical peatlands are: 464, 210, and 21 g kg for CO 2 –C, CO, and
CH 4 gases, respectively. However, there are still uncertainties about the relationship
between GHGs emission to biomass burning as only a few empirical based parameters of fuel loads and their combustion efficiency are currently reported in the
tropics. Huijnen et al. (2016) reported that in September and October 2015, when
widespread forest and peatland fires burned over large parts of Southeast Asia, a
large amount of terrestrially stored carbon was released into the atmosphere, primarily in the form of CO 2 , CO, and CH 4 . At the time, a mean emission rate of 11.3
Tg CO 2 per day was recorded. More studies are needed to complement existing data
toward achieving a reliable estimate of CO 2 emission from burning in drainage
tropical peatlands.
15.3.2 Rewetted Peatlands
In the “rewetted organic soils,” the net emission that occur are calculated based on
the net flux of CO 2 –C (emission or removal) from the rewetted organic soils and the
net flux of CH 4 –C (commonly emission) from the rewetted organic soils. CO 2 –C
(emission or removal) from the rewetted organic soils is the accumulation of CO 2 –C
emission/removal from the soils and non-tree vegetation (CO 2 –C composite ) and
off-site CO 2 –C emission from dissolved organic carbon exported from rewetted
organic soils (CO 2 –CDOC). For CO 2 –C composite emission in the tropics, since there
are no data available for rewetted organic soils, the emission factor can be assumed
to be zero. This value is based on observations of areas that are not drained so that it
reflects the fact that successful rewetting effectively reduces soil decomposition of
organic matter and stops oxidation of soil organic matter, and the decomposed
organic matter is not oxidized due to saturated conditions. Calculation of CO 2 –
CDOC emission in the tropics can use a default value of emission factor of 0.51 t
CO 2 –C ha
À1 year
À1 (IPCC 2014). CH 4 emission and uptake from “rewetted organic
soils” are generated from net CH 4 production-oxidation and CH 4 emission generated
by burning soil organic matter during fires. The probability of a fire occurring in the
“rewetted organic soils” is less likely to occur if the position of the water level
approaches the surface, but if there is a fire the resulting emission must be included
as well as the resulting N 2 O emission. The same approach for peat fires in the
drained peatlands is used. CH 4 emission resulting from organic soil decomposition
by microbes in anaerobic conditions in the “rewetted organic soils” in the tropics can
use a default value of emission factor of 41 kg CH 4 –C ha
À1 year
À1 (IPCC 2014).
N 2 O emission from “rewetted organic soils” are controlled by the amount of nitrogen
available for the nitrification and denitrification processes, as well as the availability
of oxygen needed for the chemical reaction. In tropical peatlands with saturated
condition, this can encourage denitrification and N 2 O consumption, but in practice
this effect is very small and is considered to be negligible.
15 Climate-Responsible Management of Tropical Peatlands: The Need for Integrated. . .
451