Effects of deforestation on soil and atmospheric carbon balance in Sungai Menyala Forest, Port Dickson, Malaysia
Soil CO2 efflux has been identified as playing a key role in the forest carbon balance, as logging and recovering forest ecosystems increase CO2 efflux into the atmospheric carbon pool in response to changes in environmental factors such as soil temperature and soil moisture. Hence, it is essenti...
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/114009/1/114009.pdf |
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| Summary: | Soil CO2 efflux has been identified as playing a key role in the forest carbon balance,
as logging and recovering forest ecosystems increase CO2 efflux into the atmospheric
carbon pool in response to changes in environmental factors such as soil temperature
and soil moisture. Hence, it is essential to understand soil CO2 efflux in forests of
different ages, logged-over areas and the carbon cycles in the tropical lowland forest
of Peninsular Malaysia.
The aim of this study is to assess soil CO2 efflux from logged-over forest and
recovering forest of different age and it effects on the atmospheric carbon balance. A
study was conducted in the recovering tropical lowland forest of Sungai Menyala,
Port Dickson, Peninsular Malaysia. Five experimental plots were established based
on logged-over area, recovering forests of different ages (10, 30, 50, and 70-year
forests) and tree mixed species, as this is significant in efflux estimation and the
effect of soil CO2 efflux from these various forest of different age. Soil CO2 efflux
measurement was conducted in the day time from February to June and September to
December 2013, using a constructed continuous open flow chamber technique
connected to a multi gas-handling unit and infrared CO2/H2O gas analyser.
The soil temperature and soil moisture were measured while forest biomass; total
above ground biomass (TAGB), below ground biomass (BGB), total forest carbon
(SOCs), soil organic carbon stock (SOCstock) and total organic carbon (TOC), soil
organic carbon (SOC), soil pH, bulk density and carbon to nitrogen ratio (C/N) were
measured and analysed based on the standard method. The results indicated that the
soil CO2 efflux varies, temporarily increasing from February and peaking in June and
decreasing from September to December parallel to the soil temperature and soil
moisture. The efflux rate showed a positive and significant correlation between soil
CO2 efflux, soil temperature and soil moisture, forest biomass carbon input, changes
in total organic carbon and soil organic carbon (R2=0.958; p˂0.01), suggesting that
the environmental factors influence the soil CO2 efflux. The results showed that soil
CO2 efflux was the highest in the logged-over area and decreased as the forest increased in age: 10, 30, 50, 70-years old recovering forest at 392.14, 383.07, 372.26,
329.18 and 319.08 mg m-2 h-1, respectively, and, in comparison, the primary forest
was recorded to emit the lowest CO2 efflux at 301.23 mg m-2 h-1. A high percentage
of TOC, SOC and SOCstock concentration occurred within the top 10 cm soil depth
and decreased with the depth. Similarly, a high amount of forest biomass carbon
input was recorded, both tending to be significantly higher in the older forest and
decreased with forest age.
The soil temperature was observed to increase from February to June and decrease
from September to December while the soil moisture decreased during the Southwest
monsoon regime and increased during the Northeast monsoon period, thereby
increasing the soil CO2 efflux. These results indicated that the soil CO2 efflux
increased in the logged-over forest and decreased as the forest recovered. This is
attributed to the high activities of microorganisms in the presence of changes in the
environmental factors and soil properties, and exposure of the surface of the land
directly to heat in the logged over area. In comparison, the lower soil CO2 efflux in
the recovering forests increased their carbon use efficiency, as the increase in the
canopy cover in the recovering forest absorbed the CO2 for photosynthesis, caused
refraction of the solar radiation and regulated the forest floor temperature. The high
percentage of CO2 efflux into the atmospheric carbon pool from the logged area
signified that logging activity has wide-reaching consequences and displaced a
considerable amount of soil CO2 into the atmospheric carbon pool, and had a marked
influence on the atmospheric carbon balance. In spite high soil CO2 efflux recorded
from the logged-over forest, the percentage of soil CO2 reduction between the
logged-over forest and the recovering forest ranged between 2.31 to 23.18%. This
Indicate that forest recovering would serve as a carbon sink and forest logging will
be an implication for the atmospheric carbon balance. |
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