46 just about 2 which occupied the area about 289,858 ha 33.4. The land use
category which increased quite significantly during 2002 – 2005 was Grassland from 140,763 ha to 184,672 ha or increased for about 43,909 ha. In 2008,
Cropland area has exceeded Forest land area by occupying 43 of Siak District or increased significantly about 83,436 ha whereas at the same time Forest land
occupied only 27.2 of Siak District. During 2002 – 2005 Grassland which increased quite high, yet during 2005 – 2008 increased only 0.5.
Table 7. The Area of Land Use Categories in Siak District
No Land Use
Category 2002
2005 2008
1 Forest land
406,010.91 320,593.74
235,819.17 2
Cropland 271,353.35 289,858.07
373,294.66 3
Grassland 140,763.72 184,672.94
189,259.40 4
Wetlands 12,814.17 12,814.17
12,814.17 5
Settlements 7,909.02 14,054.03
19,340.58 6
Other lands 29,266.65
46,124.86 37,589.83
Total Ha 868,117.82
868,117.82 868,117.82
Settlements area increased quite significantly during 2002 – 2008. In 2002, settlements occupied for only 7,909 ha, but in 2005 it increased almost twice,
became 14,054 ha or 1.6 of the total area of Siak District. The settlements development continued, and in 2008 the settlement area became 19,340.58 ha or
2.2 of Siak District. The land use category which changed dynamically was Other lands. In 2002, Other lands occupied Siak District for about 3.4 of total
area 29,266 ha, and in 2005 it increased for about 16,858 ha and occupied for about 5.3 of Siak District. But in 2008, Other lands decreased which occupied
Siak District about 4.3 of total area 27,589 ha. During 2002 – 2008, Wetlands were conditioned in stable condition which occupied Siak District about 1.5 of
total area of Siak District or 12,814 ha.
47 Figure 16. Land Use Maps of Siak District Year 2002, 2005 and 2008
48
4.2 Land Use Change Detection
Land use change detection is conducted in order to derive the information of land use transitions during two different time series in one time period. In this
research, land use change detection has been done in two time periods that are 2002 – 2005 and 2005 – 2008. The land use change detection has been done by
overlaying two time series of land use maps to produce land use change map and transition and probability matrices. Land use change map shows the
transformations of land uses spatially, whereas the matrices show the aggregation of land use transitions and the probability of land uses transform to other land
uses. The land use categories which are used in this research are 6 land use
categories, and naturally there would be 36 land use transitions in one period of time, but due to Wetlands were assumed in stable conditions no change, so there
would be only 26 land use transitions in this research. For convenient reason in visualizing the land use change maps, each land use transition has been coded into
integer number 1 – 26 which expressed its unique land use transition as illustrated on the table below. The same coding procedure has been also applied in
developing the land use change modeling in further activity. Table 8. Coding Procedure of Land Use Transition Matrix
t-2 Land Use
Category F C G W S O
F FF FC FG FW FS FO
C CF
CC CG CW CS CO G
GF GC GG GW GS GO
W WF
WC WG
WW WS
WO S
SF SC SG SW SS SO
t-1 O
OF OC OG OW OS OO
t-2 Land Use
Category F C G W S O
F 1 2 3 FW 4 5
C
6 7 8
CW 9 10 G
11 12 13 GW 14 15
W WF
WC WG
16 WS
WO S
17 18 19 SW 20 21
t-1 O
22 23 24 OW 25 26 F = Forest land, C = Cropland, G = Grassland,
W = Wetlands, S = Settlements, O = Other lands
49
4.2.1 Land Use Change 2002 - 2005
Siak District was dominated by Forest land, Cropland, and Grassland during 2002 – 2005. Forest land was land use category which has largest area in
2002, and was followed by Cropland and Grassland respectively. Overall during 2002 - 2005, Forest land decreased, whereas Cropland and Grassland increased.
Forest land was land use category which had biggest transitions rather than other land uses. The total area of Forest land transformed into other land uses was
123,124 ha which means about 30 of Forest land in 2002 transformed into other land uses. Mostly, Forest land transformed into Cropland 50,624 ha or 12.5 of
Forest land in 2002 and Grassland 45,964 ha 11.3, and about 25,711 ha 6.3 transformed into Other lands. In the same period, only 37,706 ha of other
land uses transformed into Forest land which were dominated by Cropland and Grassland, 23,637 ha 7.4 of Forest land in 2005 and 10,635 ha 3.3
respectively. From the discussion above, this research found that there are 123,124 ha of Forest land that has been converted to other land uses
deforestation and only 37,706 ha of Siak District had experienced reforestation.
Figure 17. Land Use Change Map 2002 – 2005 Snapshot
Cropland was the second land use which had large transitions, and mostly transformed into Grassland 64,807 ha or 23.9 of Cropland in 2002, Forest land
23,637 ha 8.7, and Other lands 11,736 ha 4.3. At the same time, Cropland had also enlargements which were contributed reversely by Grassland
55,591 ha or 19.2 of Cropland in 2005, Forest land 50,624 ha 17.5, and
