Effect of logging operations on soil carbon storage of a tropical peat swamp forest in Sarawak, Malaysia
There is little published data on the effect of logging operation on soil carbon storage of peat swamp forests. Furthermore, there is still lack of study that compares the damage level caused by “kuda-kuda” (sledge) skidding system and excavator skidding system in peat swamp forests. Thus, it is...
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Format: | Thesis |
Language: | English |
Published: |
2010
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Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/77994/1/t%20FSPM%202010%202%20ir.pdf |
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Summary: | There is little published data on the effect of logging operation on soil carbon
storage of peat swamp forests. Furthermore, there is still lack of study that
compares the damage level caused by “kuda-kuda” (sledge) skidding system
and excavator skidding system in peat swamp forests. Thus, it is important to
investigate the severity of degradation of peat swamp forest caused by
logging operation in terms of its function as carbon storage. There are four
major components of the logging operation, but the special concern remains
the skidding component because it mainly interacts with the ground while
extracting the trees through its damaging impact on the soil. The study area
is located in an area bound by Batang Lebaan and Batang Igan River,
adjacent to Sibu town. This peat swamp forest is Alan Batu forest type which
is generally found on a more stressful environment of the peat swamp. In this
study, it was assumed that conditions of the study site before the introduction
of skidding system were in their natural state, and the changes measured are
mainly caused by the skidding system. Therefore, the first part of this study
was to determine the soil carbon storage of a tropical peat swamp forest in their natural state. Variables obtained such as bulk density, soil pH, SOM,
total carbon, total nitrogen, and C/N ratio was evaluated against their typical
standard range that reported on earlier published references. The correlation
between aforementioned chemical properties, humic acid (HA), unstable
carbon, and stable carbon was examined. This tropical peat swamp forest
portrays its specific natural state such as rich in SOM but had extreme acidic
environment, thereby inhibiting decomposition of organic matter. It also had
large amounts of total carbon, low total nitrogen, and high C/N ratio. The soil
carbon storage in this tropical peat swamp forest relates to unstable carbon.
A high value of soil carbon storage (± 61.49% of unstable carbon) in this peat
swamp forest soil suggests that this natural tropical peat swamp forest plays
an important role as a sink rather than a source of carbon. The second part
of the study was to determine whether rainfall affects soil carbon storage of a
tropical peat swamp forest and to determine the correlations which exist
between variables (pH, SOM, total carbon, total nitrogen, total phosphorus,
C/N ratio, C/P ratio, HA, unstable carbon, and stable carbon) that cause
changes in soil carbon storage. The aforementioned variables of paired plots
under two different rainfall gradients were compared and their correlations
were examined. Stable carbon positively correlated with unstable carbon
under higher rainfall. However, stable carbon had no association with
unstable carbon under lower rainfall. The percentage of stable carbon of
unstable carbon was 42.93% under lower rainfall, while that of higher rainfall
was 62.69% suggesting that this natural tropical peat swamp forest plays an
important role as a sink rather than a source of carbon under higher rainfall
but inversely under lower rainfall. The third part of the study was to determine whether skidding operations affects soil carbon storage of a tropical peat
swamp forest. Bulk density and variables such as soil pH, SOM, total carbon,
total nitrogen, total phosphorus, C/N ratio, C/P ratio, HA, unstable carbon,
and stable carbon of independent plots under the two systems, “kuda-kuda”
(sledge) and excavator skidding systems were compared and the
correlations between variables were examined. It showed that the use of
skidding systems on tropical peat swamp forest alters their carbon storage
particularly unstable carbon by altering their decomposition rates. The fourth
part of the study was to determine whether logging operation affect soil
carbon storage of a tropical peat swamp forest. Variables such as soil pH,
SOM, total carbon, total nitrogen, total phosphorus, C/N ratio, C/P ratio, HA,
unstable carbon, and stable carbon under the two treatments (before and
after logging) were compared and the correlations between these variables
were examined. Result indicates that after the peat swamp forest is logged,
humification maintained but the process slows and poor, hence unstable
carbon decomposes faster instead of being preserved as stable carbon.
Logging operations in this peat swamp forest does not alter their amount of
soil carbon storage (stable carbon) due to the carbon in humic acid is quite
stable within one year. |
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