Factors responsible for spatial and temporal variation of soil CO2 efflux in a 50 year recovering tropical forest, Peninsular Malaysia

Abstract

Environmental abiotic and biotic factors are important in controlling soil CO2 efflux in forest ecosystems of different ages, as they play an important role in soil respiration. In understanding the spatial and temporal variation of soil CO2 efflux after several years of forest logging, there is a need to quantify the changing soil properties, environmental factors, and the total above and below ground biomass. This study was conducted in a 50-year old recovering tropical lowland forest in Peninsular Malaysia, measuring soil CO2 efflux using the continuous open flow chambers technique connected to a multi gas-handling unit and infrared gas analyser. The aim of this study was to determine the spatial and temporal variation of soil CO2 efflux in relation to changes in soil properties, environmental factors and forest carbon in a recovering forest. The efflux rates of about 389.20, 634.78, 564.81, 537.92 and 428.72 mg m−2 h−1, respectively, varied across the days and months, increasing from February and attaining the maximum in March and then gradually decreasing from April to June. The soil properties revealed a considerable amount of soil organic carbon, total organic carbon, and soil organic carbon stock, while the total above ground biomass, below ground biomass, soil pH, nitrogen to carbon ratio were found to provide nutrients for microbial activities in soil and to emit soil CO2. The multiple linear regression model indicated that the soil temperature and moisture explained the spatial and temporal variation in soil CO2 efflux; likewise, the changes in the soil properties and forest carbon significantly increased the soil CO2 efflux indicating a strong positive correlation (R 2 = 0.93).

Forest Recovering and Soil Respiration Rate

“…In this study, the increase in soil respiration was attributed to the change in environmental factors as was observed to be one of the important controlling factors as it was influenced by deforestation activity on the recovering forest [38]. The soil temperature within the period of the study ranged between 24.99 and 25.98 0 C, similar to the study conducted by [34], which stands to alter changes in environmental variables, likewise, soil moisture occurred at a ranged between 20.22 and 25.43%.Furthermore, forest recovering from deforestation could influence the entire environmental factors, which explains the role of deforestation and less dense forest canopy cover as it increases the net radiation on the forest floor to provide a condition to necessitate microorganisms to facilitate soil respiration [33,37].…”

“…There wasa steady decrease in efflux rate between August and November at an average mean of 340.30, 308.12, 286.07 and 256.05 mg m -2 h -1 , respectively, much lower than Pasoh forest reserve lowland Peninsular [34,35], which was strongly influenced by the availability of soil moisture and was significant correlated (p<0.05). Our finding revealed that monthly variation in soil respiration was influenced by both soil temperature and moisture as was also reported by [36].The rise and decrease in soil respiration for the period of measurement was recorded to be parallel to soil temperature and soil moisture which indicated soil respiration had positively and significantly correlation with both soil temperature and moisture (p<0.05).…”

“…The recorded input from TAGB, BGB and SOCs were found to be considerable and similar the observed result from the tropical forest conducted by [33], likewise the C/N ratio occurred at 34.24-48.55 / 1.16-1.35 % to increase the rate of decomposition. The considerable amount of these forest biomass and C/N in the recovering forest are found to influenced the rate of soil carbon stock (SOCstock) by 52.28 mg ha -1 and soil properties, similar to the tropical forest of India [40] and lowland tropical forest of Malaysia [34], respectively. This result confirmed the significant role played by the forest biomass and C/N ratio to increase soil nutrient for microorganism to emit soil CO 2 as was also reported by [22]and [41].…”

Soil Carbon Dioxide Efflux and Atmospheric Impact in a 10-Year-Old Dipterocarpus Recovering Lowland Tropical Forest, Peninsular Malaysia

“…The duration of the study represents the three seasons of the tropics (post-monsoon, pre-monsoon and monsoon period). reduce the build-up of pressure on the soil interphase, and monitored with a barometer [11]. The infrared gas analyser was calibrated in the laboratory using CO 2 as zero standards (1,000 g).…”

“…As a result of this logging, quantifying the associated environmental factors to influence soil CO 2 efflux is the key to estimate the soil CO 2 efflux rate. The mechanistic links of logging activity, environmental factors, soil properties and soil CO 2 efflux are poorly understood under the tropical deforested tropical forest [11], and the important step is to determine their interactive links and effect.…”