Agricultural, veterinary and food sciences

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Browsing Agricultural, veterinary and food sciences by Subject "Carbon cycle (Biogeochemistry)--Research"

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    Estimating primary productivity of oil palm in Peninsular Malaysia using remote sensing and ancillary data
    (Universiti Teknologi Malaysia, 2014) Tan, Kian Pang
    The amount of carbon sequestration by vegetation can be estimated using Gross Primary Productivity (GPP) and Net Primary Productivity (NPP). GPP estimates the total values of carbon intake by vegetation, while NPP is the value of GPP deducting the respiration by vegetation. Understanding GPP and NPP values at a regional scale is essential to study the roles of an ecosystem in the global carbon cycle. Estimating oil palm GPP and NPP values at a regional scale is feasible using remote sensing techniques. Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra and Aqua satellites have been providing GPP and NPP values, namely MOD17, for ecosystems across the globe since 2002, but the suitability of the product for oil palm ecosystem has not been evaluated. This study evaluated the MOD17 product and its upstream inputs using oil palm biometric data, local meteorological data, land use data from map, Leaf Area Index (LAI) and fractional Photosynthetically Active Radiation (fPAR). Biometric data such as breast height diameter, age and the height of the trees were collected from field works. This study used several oil palm allometric equations to estimate the total biomass and carbon content of oil palm trees. Annual NPP of oil palm was calculated from the difference between the total carbon at a certain age and the total carbon of the following age. The upscale oil palm LAI and fPAR were derived based on a regression model between the hemispherical photographs derived oil palm LAI, and band 1 (Near Infrared) from the Second Disaster Monitoring Constellation of the United Kingdom (UK-DMC 2) satellite data. The discrepancies between the MOD17 product and its inputs were reported. By replacing all the upstream inputs from the MOD17 product with maximum light use efficiency for oil palm plantations as a constant at 1.68 gCm-2, annual photosynthetically active radiation from local meteorological stations and upscale fPAR, the amount of oil palm GPP and NPP values for Peninsular Malaysia were estimated to be 0.09 PgC per year and 0.03 PgC per year respectively. Since the age of oil palm trees is one of the most important variables that affects oil palm GPP and NPP values, this study investigated the use of optical and radar remote sensing to discriminate the age of oil palm trees. The results show that young (1-3 years old) and matured (more than 3 years old) oil palm trees can be distinguished. However, discriminating the age between matured oil palm trees is difficult due to the low variation in oil palm canopy which stabilizes at about ten years old. The inputs of the MOD17 product will need to be improved if GPP and NPP values are to be used to estimate carbon sequestration from oil palm ecosystem