Abstract
Total aboveground carbon (TAC) and total soil carbon stock in the agroforestry system at the Balung River Plantation, Sabah, Malaysia were investigated to scientifically support the sustaining of natural forest for mitigating global warming via reducing carbon in the atmosphere. Agroforestry, monoculture, and natural tropical forests were investigated to calculate the carbon stock and sequestration based on three different combinations of oil palm and agarwood in agroforestry systems from 2014 to 2018. These combinations were oil palm (27 years) and agarwood (seven years), oil palm (20 years) and agarwood (seven years), and oil palm (17 years) and agarwood (five years). Monoculture oil palm (16 years), oil palm (six years), and natural tropical forest were set as the control. Three randomly selected plots for agroforestry and monoculture plantation were 0.25 ha (50 × 50 m), respectively, whereas for the natural tropical forest it was 0.09 ha (30 × 30 m). A nondestructive sampling method followed by the allometric equation determined the standing biomass. Organic and shrub layers collected in a square frame (1 × 1 m) were analyzed using the CHN628 series (LECO Corp., MI, USA) for carbon content. Soil bulk density of randomly selected points within the three different layers, that is, 0 to 5, 5 to 10, and 10 to 30 cm were used to determine the total ecosystem carbon (TEC) stock in each agroforestry system which was 79.13, 85.40, and 78.28 Mg C ha−1, respectively. The TEC in the monoculture oil palm was 76.44 and 60.30 Mg C ha−1, whereas natural tropical forest had the highest TEC of 287.29 Mg C ha−1. The forest stand had the highest TEC capacity as compared with the agroforestry and monoculture systems. The impact of planting systems on the TEC showed a statistically significant difference at a 95% confidence interval for the various carbon pools among the agroforestry, monoculture, and natural tropical forests. Therefore, the forest must be sustained because of its higher capacity to store carbon in mitigating global warming.
Highlights
Carbon is stored on the Earth in various forms and the major reservoirs are organic compounds in living and dead organisms of the biosphere, carbon dioxide (CO2 ) and methane (CH4 ) gases in the atmosphere, in the organic matter of soil, in the lithosphere as fossil fuel and sedimentary rocks, in the oceans as dissolved hydrocarbons, in the shells of marine creatures as calcium carbonate, etc.The movement of carbon in many forms among the atmosphere, hydrosphere, biosphere, pedosphere, and lithosphere is known as the global carbon cycle [1]
There was no clear pattern in the tree density of agarwood trees between the agroforestry systems
Despite the lower total ecosystem carbon (TEC) values, this study showed similar pattern to the research conducted by Ziegler et al [19] in which the forest contributed to higher TEC, followed by agroforestry and monoculture plantation
Summary
Carbon is stored on the Earth in various forms and the major reservoirs are organic compounds in living and dead organisms of the biosphere, carbon dioxide (CO2 ) and methane (CH4 ) gases in the atmosphere, in the organic matter of soil, in the lithosphere as fossil fuel and sedimentary rocks, in the oceans as dissolved hydrocarbons, in the shells of marine creatures as calcium carbonate, etc.The movement of carbon in many forms among the atmosphere, hydrosphere, biosphere, pedosphere, and lithosphere is known as the global carbon cycle [1]. An undisturbed tropical forest area stores a higher amount of carbon stocks in the living biomass and in the soil as compared with other land uses [5]. The conversion of forest ecosystems into various land uses and land cover changes (i.e., forest conversion into other land cover) is believed to be one of the major sources of greenhouse gases (GHGs) emissions in the atmosphere [7]. Conversion of the natural ecosystem into various land use purposes destroys the landscape and the deforested landscapes fail to capture and store CO2 , which is the main GHGs component
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