where R
n
is the net-radiation MJ m
-2
month
-1
, G is the heat flux at ground level assumed to be 0,
γ is the constant psychometric with a value of about 66 Pa K
-1
. and
α are the latent heat of evaporation and the empirical factor of with values 2.5 MJ Kg-1 and 1.26 respectively.
Δ is calculated using the following mathematical equation:
Δ = 2504 exp [17.27 T T + 237.2] T + 237.3
2
where Δ is the slope vapour pressure curve KPa
o
C
-1
and T the air temperature
o
C.
3.4.5 Validation with the ground check
The result of the calculation should be validated with the ground check. Validation of the NPP is an essential step in establishing its utility; however,
validation is challenging because of a variety of scaling issues Morisette et al. 2002, Turner et al. 2004. Site-level validation of MODIS NPP has been more
limited because of the logistical constraints of measuring NPP and scaling it to the size of a MODIS grid cell Turner et al. 2004, 2005. These efforts have likewise
found site-specific differences in the degree of agreement between ground-based and MODIS-based NPP estimates. The MODIS NPP algorithm requires the
computation of autotrophic respiration Ra based on inputs of leaf area index LAI and temperature, along with look-up table values for constants and the base
rate of respiration Running et al. 2000. Specific problems with the Ra component of NPP have been identified in some cases Turner et al. 2005.
It is widely known that tower flux measurements of Net Ecosystem Production NEP can be used for model validation at the small site scale.
Nevertheless, we have not included comparisons of tower-based NEP to NASA- CASA modeled NEP in this island study, because tower eddy flux estimates are
not designed to represent large-scale e.g., 8 km NEP fluxes that we model with NASA-CASA.
NEP is named ecosystem carbon sink positive value or carbon source negative value. It is a key characteristic to measure ecosystem carbon uptake or
release. Theoretically, when an ecosystem matures, e.g. climax, it is in equilibrium with the climate and soil environment, so the carbon uptake and
release are balanced, and NEP approximates to zero. But if the environmental conditions, such as climate, changed, the ecosystem carbon budgets were not
balanced. In any year over the past nine years, net ecosystem production can be very
large in one location but very small or negative in another location because of the spatial heterogeneity of vegetation, soils and climate. Locations with large
positive annual NEP are often those that receive a high amount of precipitation. In contrast, locations with negative NEP are often those that receive little
precipitation. Year-to-year changes in spatial pattern of NEP were most probably caused by changes in the spatial pattern of precipitation, which can be changed
dramatically by the El Nino events Vörösmarty et al. 1996. For this research, different samples from different areas for ground check
were considered. The first area was related to the place where the highest value of NPP is found. The second area was a place where the lowest value of NPP is
found. For that, we checked on the ground what kind of features exists exactly in the area, and how can we come up with a conclusion based on what we found in
the area with our system. A sample for water body has been taken on the Mahakam River which is
the largest river in East Kalimantan, Indonesia, with a catchment area of approximately 77,100 km
2
. The catchment lies between 2˚N to 1˚S latitude and 113˚E to 118˚E longitude. The river originates in Cemaru Van Bemmelen 1949
from where it flows south-eastwards, meeting the River Kedang Pahu at the city of Muara Pahu. From there, the river flows eastward through the Mahakam lakes
region, which is a flat tropical lowland area surrounded by peat land. Thirty shallow lakes are situated in this area, which are connected to the Mahakam
through small channels. The samples for forests have been taken in different areas. However, some
parts of the very deep forest one was in Tandilang Forest, located in the village called Sulang’ai, Sub-district of Batang Alai Timur, Hulu Sungai Tengah Regency,
in South Kalimantan Province.
Over the past decade, the government of Indonesia has drained some peat swamp forests of the island of Borneo for conversion to agricultural land. The dry
years of 1997-8 and 2002-3 saw huge fires in the peat swamp forests. A study for the European Space Agency found that the peat swamp forests are a significant
carbon sink for the planet, and that the fires of 1997-8 may have released up to 2.5 billion tonnes, and the 2002-3 fires between 200 million to 1 billion tonnes, of
carbon into the atmosphere. Much of the emissions from peatlands in Borneo are due to changes in their hydrological regime, caused by drainage from nearby
plantations particularly oil palm. Peatland conservation and rehabilitation are more efficient undertakings than reducing deforestation in terms of claiming
carbon credits from REDD initiatives, due to the much larger reduced emissions achievable per unit area and the much lower opportunity costs involved Mathai
2009. Indonesia contributes 50 percent of tropical peat swamps and 10 percent of dry land in the world. The ground check for peatland was done in a vast peatland
area called “Jl Asang Permai Gambut”. Deeper analysis in Indonesia suggests that oil palm development might be
a cover for something more lucrative: logging. Recently much has been made about the conversion of Asias biodiversity rainforests for oil-palm cultivation.
Environmental organizations have warned that by eating foods that use palm oil as an ingredient, Western consumers are directly fueling the destruction of orangutan
habitat and sensitive ecosystems. However, oil-palm plantations now cover millions of hectares across Malaysia, Indonesia, and Thailand.
Palm oil became the worlds number one fruit crop, trouncing its nearest competitor, the humble banana because of its crops unparalleled productivity.
Palm oil is the most productive oil seed in the world. A single hectare of oil palm may yield 5,000 kilograms of crude oil, or nearly 6,000 liters of crude. The
ground check for palm oil was done at the “Kebun Kelapa Sawit Pelaihari”, a palm oil plantation owned by PT. Perkebunan Nusantara XIII PERSERO.
Mining sector in South Kalimantan Province is dominated by oil, natural gas and coal, but oil and natural gas is inclined to have decreased, coal precisely
have very fast increasing amount. Coal has been blamed as a major contributor to greenhouse gas emissions. The South Kalimantan Province is an area with
abundant deposits of coal and contributes 16.36 to the national coal stock. Coal mining is a profitable business. It creates employment, generates value, and
improves the foreign investment of a country or region. However, coal mining has its disadvantages including not to mention the impact to the environment. Since it
was impossible to go through the mining area, we took the points as close as the mining area as possible and we also took some points from some remaining areas
and conditions of previous mining activities. For residential area, the ground check was done in Pangkalan Bun, capital
of the Kotawaringin Barat regency, in the western part of Central Kalimantan. This is the entry point to reach Tanjung Puting Park in the southern part, and the
Dayak villages in the north of Central Kalimantan Province.
IV. RESULTS
