Background Spatial distribution of net primary production (NPP) using modis data and correlation with climate variability

2 report also revealed that the main cause of increasing greenhouse gas GHG such as the increase in Carbon Dioxide gases caused by fossil fuel use and land-use change, from forest land into economic value of land, such as settlements and plantations. Net Primary Production NPP is the net carbon fixed by vegetation through photosynthesis. NPP provides the carbon required for maintenance of the structure and functions of an ecosystem. We can use NPP in the term of net biomass accumulation to express the net flux of carbon between the atmosphere and terrestrial vegetation. NPP is a fundamental ecological variable, not only because it measures the energy input to the biosphere and terrestrial carbon dioxide assimilation, but also because of its significance in indicating the land surface area and status of a wide range of ecological process. Net primary productivity NPP is an important component of the carbon cycle and a key indicator of ecosystem performance. NPP is driven by solar radiation and can be constrained by light, precipitation and temperature. Global NPP of vegetation can be predicted using the relationship between leaf reflectance properties and the absorption of photo synthetically active radiation Running and Nemani 1998; Goetz and Prince 1998. The Enhanced Vegetation Index EVI has been shown to be well correlated with LAI, biomass, canopy cover, and the fraction of absorbed photo synthetically active radiation Gao et al., 2000, and therefore is useful for monitoring seasonal, inter-annual, and long-term variation of the vegetation structure Huete et al., 2002. Study about NPP for tropical forest is very important, because Indonesia is one of the countries located in the tropical area which has large area of tropical forest. Information on net primary production in tropical forests is needed for the development of realistic global carbon budgets and to provide information to support for carbon trading also to provide of how these ecosystems will be affected by climatic and atmospheric changes. On one hand, climate change and increasing CO 2 can cause changes in net primary production NPP and carbon storage in ecosystems. On the other hand, terrestrial ecosystems can affect climate through carbon, water, and energy 3 exchange. Understanding the response of terrestrial NPP and the carbon cycle to climate change is for predicting future environmental change and mitigating the impacts Nemani et al., 2003; Prentice et al., 2001. Climate is average weather for a given place or a region. It defines typical weather conditions for a given area based on long-term averages. Climate varies on all time scales, from one year to the next, as well as from one decade, century or millennium to the next. Although an areas climate is always changing, the changes do not usually occur on a time scale that is immediately obvious to us. However climate variations happen on all time scales, as well as on all spatial scales, from the regional to the global. As an example, the oceanic El Nino and La Nina phenomenon is most pronounced in the tropical Pacific off the coast of Peru, but the associated Southern Oscillation in the atmosphere has far-reaching, nearly global implications. This research will study about the correlation of NPP in normal condition and in extreme condition of climate variation, i.e. some regions may become increasing carbon sink whereas others may become increasing carbon source under the same future climate change scenario. 4

1.2. Objectives

There are several objectives designed for this research, which are:  To estimate net primary production NPP and annual carbon balance using MODIS imagery over Sumatra terrain during 2001 –2009.  To find correlation between the distribution of NPP and the climate variability especially during El-Nino and La-Nina phenomenon using MODIS imagery over Sumatra terrain 5 II. LITERATURE REVIEW

2.1 Carbon Cycle

Carbon is exchanged between atmosphere and the ocean by physical and chemical process. Human activities are involved with global carbon cycle. In particular, human activities create two new flux of carbon released to atmosphere. When forests are cleared for timer production or agricultural process, some of the carbon stored in the trees and soil is released to the atmosphere. Fossil fuel contained carbon molecule. The burning of fossil fuel for automobile and industrial uses released a several giga ton of carbon per year to the atmosphere. Figure 2.1 show the diagram of carbon cycle, at right side of the figure indicates a natural production of carbon cycle and left side indicates human activities involved to the carbon cycle. Source : http:esd.ornl.gov Figure 2.1 Global diagram of carbon cycle Based on the data from Intergovernmental Panel on Climate Change IPCC, 2001, CO 2 concentration in the atmosphere increase rapidly becomes 367 in 1999. Based on the data recorded and model prediction that has developed,