Judul: Estimation Of Net Primary Production (NPP) using Remote Sensing Approach and Plant Physiological Modeling.
Abstrak: Net Primary Production (NPP) is the amount of CO2 absorbed and kept inside vegetation per unit area and per unit time. It is a difference between photosynthesis and plant respiration in an ecosystem that can express the net flux of carbon between the atmosphere and terrestrial vegetation. Information NPP of tropical forests is important for the development of realistic global carbon budgets and for projecting how these ecosystems will be affected by climate changes. This research utilized remotely sensed data and micrometeorological measurement to provide information on vegetation condition. The objective of this research is to estimate spatial NPP using remote sensing approach and plant physiological/micrometeorological modeling. The study area is a tropical peat swamp forest at Kalampangan site, Central Kalimantan, Indonesia. Micrometeorological data are used to provide climatic information and input for modeling NPP. The estimation of NPP is conducted using modeling approach, which is based on relationship between radiation use efficiency, photosyntetically active radiation and fraction of absorbed photosynthetically active radiation by the plants' s canopy. Microclimate variation during 2001 - 2002 is relatively low. In June 2002 El Nino phenomenon is started, causing higher air temperature and lower precipitation. Other effects are decreasing of solar radiation and PPFD, due to the shading caused by the smoke emitted from large scale peatland fires. Trend of NDVI derived using micrometeorological measurement showed an increase from 2001 to 2002, and then decrease from 2002 to 2004. Average different values (delta) between both methods used to derive NOVI is relatively constant around 0.33 with a high correlation of r2 = 0.98. Using remotely sensed data, the highest NPP values estimated is in year 2003 with value range between 2000 - 2500 (gC m-2 yr-1), less than 2% of the whole forest area. In 2003, 75% area has NPP between 1500 -2000 (gC m-2 yr-1), meanwhile for 2002 and 2004 it is only 21 % and 50 %, respectively. NPP values estimated using micrometeorological measurement have different values with similar pattern with NPP estimated using remotely sensed data. The pattern is that, NPP increase from 2002 to 2003, and then decrease from 2003 to 2004. The range of yearly NPP for the site is between 2000 -3000 gC m-2 yr-1• The highest NPP for Kalampangan site is in 2003, 2572 gC m-2 yea(1 , followed by 2540 gC m-2 yr-1 NPP in 2001 and 2047 gC m-2 yr-1 NPP in 2004. There is strong correlation between NPP values derived from the two methods with r2 = 0.98. Although the result has high correlation, but further research still needed. This research has been carried out with limited availability of data, with only four observations (of four different years) of satellite data. Increasing CO2 concentration in the atmosphere has resulted in increased simulated NPP values. The increase reached 30% - 31 % under double CO2 concentration in the atmosphere.
Keyword: Net Primary Production, Vegetation Indices, Carbon Cycle, Micrometeorological Modeling, Remote Sensing System