Geoscience Reference
In-Depth Information
Table 6.4
Land-Cover Change Matrix and Transitions in Study Area, Rondonia 1994-1999
1999
Sec.
Forest
Bare
Soil
Total
percentage
Total
area (ha)
1994
Forest
Transition
Crops
Pasture
Water
Forest
48.9
8.3
1.8
5.9
2.3
1.2
0.0
68.5
147,380
Sec. forest
4.8
3.5
0.3
2.5
1.3
0.5
0.0
12.9
27,759
Transition
0.1
0.2
0.0
0.4
0.2
0.1
0.0
1.0
2,234
Crops
0.3
1.2
0.2
2.1
1.4
0.4
0.0
5.6
12,072
Pasture
0.2
0.7
0.1
1.3
4.5
0.8
0.0
7.6
16,253
Bare soil
0.3
0.4
0.1
0.8
0.7
0.2
0.0
2.4
5,183
Water
0.0
0.0
0.0
0.0
0.0
0.0
2.0
2.0
4,251
Total percentage
54.6
14.3
2.6
12.9
10.4
3.2
2.0
100.0
Total area (ha)
117,553
30,731
5,554
27,833
22,386
6,823
4,252
215,132
Note:
No change 1994-1999: 61.1%.
The amount of primary forest decreased in 1999 by 30,000 ha, a negative change of 20.2% in
primary forested area. The area of deforestation observed between 1994 and 1999 was more than
twice that estimated for the 1986 to 1994 period (not shown). This represented a 4.5 times increase
compared to the 1986-1994 deforestation rate. Table 6.3 presents the change in LC for 1994-1999
as both percentage of area and percentage of change.
All the nonforest cover types increased in area between 1994 and 1999. This was largely at the
expense of primary forest. Increases in secondary forest had the dominant “gain” in area during
this period, with a total increase in area of almost 31,000 ha in 1999, followed by slightly smaller
increases in crops and pasture (27,832 ha and 22,386 ha, respectively). The most significant
increases on a proportional basis occurred with the crops and pasture cover types; both increased
over 200% during this time period.
The increase in pasture area was inflated by a tremendous deforestation event totaling approx-
imately 5000 ha in 1995 in the southeastern portion of the study site. Subsequent to clearing, the
area was partially planted with grass and later divided into small-scale farm parcels in 1995 to
1996, creating a new settlement called Pedra Redonda. The most important and broadly distributed
crop among the small-scale farms was coffee
, which received special incentives
through subsidized federal government loans and the promotional campaign conducted by the State
of Rondonia “Plant Coffee” (1995 to 1999).
The LC change matrix provides more detailed change information, including the distribution
of deforested areas into different agricultural uses (Table 6.4). For 1994 to 1999 we determined
that 61.1% of the area did not undergo LC change. This metric was calculated by summing the
percentages along the major diagonal of the matrix. Note that primary forest showed the greatest
decrease in area while concurrently exhibiting the largest area unchanged (48.9%), due to the large
area occupied by this cover type. For the remaining cover types, the change was significantly greater
(as shown throughout the diagonal of the matrix) because of the proportionally smaller area occupied
by these cover types.
The 8.3% conversion rate of primary forest to secondary forest indicates that some recently
deforested areas remained in relative abandonment, allowing vegetation to partially recover in a
relatively short period of time (Table 6.4). An increase in classes such as transition and bare soil
also indicates the same trend of new areas incorporated into farming and their partial abandonment
as well. Of areas that were primary and secondary forest in 1994, crops were the most dominate
change category (> 8%) followed by pasture (
(Coffea robusta)
4%). While the change in LC mapped from the
image classification fits with what we expect to see in the region, it is important to differentiate
(when possible) real change from misclassification. Potential errors associated with the mapping
are discussed below.
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