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Spatial database development for green house gas emission estimation using Remote Sensing and GIS

Lilik Budi Prasetyo1, Genya Saito2, Katsuo Okamoto2, Haruo Tsuruta2, Ishizuka Shigehiro3, Ueda Shingo4, Upik Rosalina1, Daniel Murdiyarso5, Atiek Widayati5
1Guest Researcher of BIOTROP (1996-1998) and staff of Faculty of Forestry,
Bogor Agriculture University, Bogor-Indonesia
2Natinal Institute of Agro-Environmental Sciences, Tsukuba-Japan
3Forestry and Forest Products Institute, Tsukuba-Japan
4National Institute for Resources and Environment, Tsukuba-Japan
5South East Asia Impact Center, Bogor-Indonesia

Abstract
Spatial digital database of Jambi Province, Indonesia from various sources of maps, remotely sensed imagery photos, field measurement and statistical data were developed using Geographical information System (GIS). The database result then were applied to make assessment of land-use/land cover change impacts on above ground carbon stock and soil surface flux of carbon dioxide (CO2) nitrous oxide (N2O) and methane (CH4)

Introduction
Deforestation, conversion of forest into non-forest land use/land cover, especially in tropical forest area has been an international concern. It was estimated that tropical forest was deforested by 6-16.8 million hectares per year. (Grainger, 1993; Barbier et. all., 1991; Myers, 1994). Since forest hold the most carbon in terrestrial ecosystem, such changes give significant impact on the net increase of atmospheric carbon. In addition, land-use and land cover results in changes in greenhouse gases dynamics.

Greenhouse gases (CO2, NO2, CH4) emission of soil is influenced by several factors such as land-used/land cover types, climatic factors, biological factors and physical environment factors. Emission measurements usually are conducted at a point location, therefore problem arise when emission estimation will be used for scaling up into a broader areas . The research aimed at the development of database to assist the regional estimation of aboveground carbon stock loss and soil surface green house gas emission changes caused by land-use/land cover changes using GIS and Remote Sensing. As a case study land-use/land cover change between 1986 to 1992 of Jambi Province, Indonesia will be evaluated.

Study Area Description
The study area is located in Jambi Province, between 0° 45′ and 20°45′ latitude south; 101° and 104°55′ longitude east (Figure.1). The total area is 48,715 sq. km. It ranges from swampy coastal plains in the east to more than 1000 meters above the sea level in the western part. According to statistical data, in 1995 the population of Jambi was 2.18 Million and has increased more than two fold compared to 1971 data. (Bappeda Jambi 1995 and 1988).

Methodology
The research is initiated by the development land-use/land cover maps, and followed field measurement. Spatial database (land-use/land cover) construction was conducted in Forest Ecology and Remote Sensing Lab. Of Regional Center for Tropical Biology (Biotrop), and Remote Sensing Lab. of National Institute of Agro-environmental Sciences, Japan. Field measurements (above grounds biomass, and greenhouse gases flux) were conducted by Biotrop, Impact Center of South East Asia and National Institute of Agro-environmental Science, Japan.

a. Land-use/land cover map construction
Spatial database (Arc/Info file) of Land-use/land cover were developed based on land-use/land cover maps in 1986 and 1992 at scale 1 : 250 000 published by Bitrop. These two maps were made based on visual interpretation of various remotely sensed imagery photographs such as Landsat MSSR and SPOT.

b. Bio-mass estimation (Aboveground carbon stock)
Weight of sample components of the tree and pole i.e. steams, branches, twigs, leaves and roots of primary forest, secondary and logged over forest were estimated by using equation developed by Kira and lwata (1989). Stern weight included stem barks, while weight of branches included twigs. For the sapling and seedling, the calculation of biomass per individual was obtained from the average weight of several saplings and seedling component was separated into leaf weight, stem weight and root tree with the number of tree per hectare. The same method is applied for poles, saplings and seedlings. Above ground biomass of the other land-use/land cover types were made based on literatures. To get aboveground carbon stock the biomass weight multiplied by factor of 0.5.

c. Soil Greenhouse gases flux measurement.
Flux of carbon dioxide, nitrous oxide and methane of soil surface were measured at various land-use/land cover types in order to obtain the estimates of diurnal emissions. The emission rates indicated by changes of methane concentration per unit time (dC/dt) were developed by plotting the analyzed air samples collected using closed-chamber method at 10-minute intervals. The Flux density is calculated as follows (Khalil et. al., 1991)
f = r V (M/Noa) (dC/dt) x 6 x 10-5
f= Methane, Nitrous oxide or carbon dioxide flux (mg/m2/hr), r = Air density (mol/m3),
V= Chamber volume (m3), M= gas molecular weight (g/mole), A= Chamber basal area (m2)
dC/dt = emission rate (ppbv/minute), obtained from consecutive measurement.

c. Combine field data measurement and GIS spatial data.
Data on aboveground carbon stock and soil surface greenhouse gases flux were combined using Look Up Table (LUT) of Arc/Info. Estimation of total above ground carbon stock were calculated by multiplying the value by total area of each land-use/land cover. The same method was applied for calculating the total emission of greenhouse gases.

Result and Discussion

Land-use/land cover changes
Figure 2a and 2b. shows land-use/land cover patterns in 1986 and 1992, while Figure 2c is the overlay result. Quantitative comparison of the changes is presented in Table 1. Proportion of primary forest decreased from 19.3% to 12.5% in 1992. Further analysis of each land-use/land cover types is presented in Figure 3. It shows that about 24% of primary forest area were converted into logged forest , shrubs (fallow lands), cash crop plantation, cultivated and settlement areas. About 30% of logged forest were converted into shrubs, cash crop plantation, a mixture of cultivated and settlements. In the case of shrubs most of them were converted into a mixture between cultivated and secondary vegetation (40.3%), cash crop plantation (7.9%), logged forest (20.2%) and secondary forest. Of about 73% of Grasslands have changed into fallow lands (48.8%), a mixture between cultivated lands and secondary vegetation(20.7%).

Land -use/Land cover 1986 1992
Area(sq.km) % of total area Total carbon
(106ton)
Area(sq.km) % of total area Total carbon
(106 ton)
Primary forest 165.21 33.91 416.89 12569.86 25.80 317.19
Secondary forest 0.00 0.00 0.00 1274.34 2.62 7.40
Logged forest 10022.39 20.57 155.53 12448.65 25.55 193.18
Fallow lands 9401.68 19.30 14.10 6072.66 12.47 9.11
Grasslands 535.99 1.10 0.32 523.19 1.07 0.31
Bare lands 3.67 0.01 0.00 3.67 0.01 0.00
Cash crops plantation 912.78 1.87 2.56 3303.17 6.78 9.25
Paddy field 1002.78 2.06 0.75 649.16 1.33 0.49
Upland field 0.00 0.00 0.00 235.84 0.48 0.18
Cultivated and Secondary Vegetation 7036.29 14.44 24.97 7933.39 16.29 28.16
Cultivated land and Settlement 1339.84 2.75 0.50 1630.68 3.35 0.61
Urban areas 0.00 0.00 0.00 132.17 0.27 0.00
Water surface/lake 42.41 0.09 0.00 42.27 0.09 0.00
No data 1896.60 3.89 1896.6 3.89
Total 48715.65 100.00 615.62 48715.65 100.00 565.88

Table 1. Land-use/land cover and above ground bio-mass changes between 1986 and 1992
Aboveground carbon stock changes
Aboveground carbon content estimation of each land-use/land cover were calculated by multiplying the area of each land-use/land cover with carbon stock per unit area. Table 1 above has showed the changes of above ground carbon due to land-use/lanc cover changes. Total above ground stock decrease from 6.16 x 108 ton in 1986 to 5.66 x 108 ton in 1992 or loss of about 0.50 x 108 ton within 6 years equal to 8.3 million ton per year. The loss of aboveground carbon was mainly came from primary forest conversion. IPCC have divided the loss of aboveground carbon content into on site and off-site release. These two categories were classified further into direct burning (fuel wood and slash and burn agricultural) and decomposition process release of unburned biomass (Houhton et. al., 1996). Thus the amount of carbon and greenhouse gas released to the atmosphere were depended on these processes. Estimation of the amount carbon and greenhouse gases release need yearly basis time series of spatial data and the information on commercial wood and fuelwood harvest, and burning efficiency data of each land-use/land cover type.

Soil Greenhouse Gas emission changes
Green house gas flux of soil varies depend on type the site condition and season. The comparison below were made based on flux measurement conducted in November 1997 in several sites of Jambi Province. The calculation results of total flux based on 1986 and 1992 land-use/land cover data for major land-use land/cover presented in Table 2 and Table 3, respectively. Comparison of the total green house gases flux of the two periods of time could not be performed since there are still no information on greenhouse gases flux of soil surface under cash crops plantation and secondary forest. However, it seems that the conversion of natural forest will cause on the decrease of Methane gas absorption and induce the increase of Nitrous oxide flux emission.

Figure 2.(a) Land-use/land cover in 1986
(b) Land-use/land cover in 1992
(c) Land-use/land cover change

Figure 3. Land-use/land cover changes from 1986 to 1992
Conclusion
Land-use/land cover changes in Jambi between 1986 to 1992 results in the loss of carbon about 8.3 millions ton annually. In addition, the process also gave impacts on greenhouse gases flux of soil surface. Information on commercial wood harvest and fuelwood consumption, and further research on burning efficiency and decomposition process are needed to assist the estimation of greenhouse gases released to the atmosphere.

References

  • Adger., W. Neil and K. Brown. 1994. 1994. Land-use and causes of global warming. John Wiley & sons. New York. 271 p
  • Ball, D. and R. Babbage. 1989. Geographical information system; defence application. New South Wales. Macathur Press. 257 p
  • Bappeda Jambi. 1985 and 1988. Jambi province statistics. Bappeda (in Indonesian)
  • Barbier, E. B, Joanne C. B. and A. Markandya. 1991. The economic of tropical deforestation. Ambio 20 (2) : 55-58
  • Houghton, J. T., et. al. Greenhouse gas inventory reference Manual : page 5.1-5.74
  • Khalil, M. A. K., R. A. Rasmussen, M. X. Wang and L. Ren. 1991. Methane emissions from rice fields in china. Environ. Sci. Tech. 25: 979-981
  • Kira, Tatuo and Keiji Iwata. 1989. Nature and Life in Southeast Asia Volume IV, 1989. Fauna and Flora Research society, Kyoto, Japan.
  • Myers, N., 1994. Tropical deforestation : rates and pattern in The causes of tropical deforestation (Brown, K. and D. W. Pearce eds.) England, UCL Press, pp 27-40

Table 2. Total green house gas flux of Jambi Province based on 1986 land-use/land cover data

Land-use/Land cover Soil surface flux of green house Gases in 1986
Flux of CO2(mg/m2/hr) Total Flux of CO2(mg/day) Flux of N2O(mg/m2/hr) Total Flux of N2O(mg/day) Flux of CH4(mg/m2/hr) Total Flux of CH4(mg/day)
Primary forest 425.00939 1.69 x 1014 0.00806164 3.2 x 109 -0.0365 -1.45 x 1010
Secondary forest  
Logged forest 514.13489 1.24 x 1014 0.01031502 2.48 x 109 -0.0431 -1.04 x 1010
Shrubs/bush 580.71275 1.31 x 1014 0.01996915 4.51 x 109 -0.0444 -1 x 1010
Grasslands 603.61323 7.76 x 1012 0.01101057 1.42 x 108
Bare lands 276.60000 2.44 x 1010 0.00644000 567235.2 -0.0071 -621844.8
Cash crops plantation
Paddy field
Upland field 425.86029 0.00711683
Cultivated and Secondary Vegetation 473.61675 8 x 1013 0.02030256 3.43 x 109 -0.0197 -3.33 x 1010
             
Total   5.11 x 1014   1.38 x 1010   -3.82 x 1010

Table 3. Total green house gas flux of Jambi Province based on 1992 land-use/land cover data

Land-use/Land cover Soil surface flux of green house Gases in 1986
Flux of CO2(mg/m2/hr) Total Flux of CO2(mg/day) Flux of N2O(mg/m2/hr) Total Flux of N2O(mg/day) Flux of CH4(mg/m2/hr) Total Flux of CH4(mg/day)
Primary forest 425.00939 1.28 x 1014 0.00806164 2.43 x 109 -0.0365 -1.1 x 1010
Secondary forest
Logged forest 514.13489 1.54 x 1014 0.01031502 3.08 x 109 -0.0431 -1.29 x 1010
Fallow lands 580.71275 8.46 x 1014 0.01996915 2.91 x 109 -0.0444 -6.47 x 109
Grasslands 603.61323 7.58 x 1012 0.01101057 1.38 x 108
Bare lands 276.60000 2.44 x 1010 0.00644000 567235.2 -0.0071 -621844.8
Cash crops plantation
Paddy field
Upland field 425.86029 2.41 x 1012 0.00711683 40282396
Cultivated and Secondary Vegetation 473.61675 9.02 x 1013 0.02030256 3.87 x 109 -0.0197 -3.76 x 109
Total   4.67 x 1014   1.25 x 1010   -3.41x 1010