Environmental Engineering Reference
In-Depth Information
1986 was gone in the year 2000 pointing out clearly the
impact of deforestation due to plantation agriculture in the
area.
The results show that settlements had a steady increase
throughout the study period (11,022, 11,312 and 13,512 ha
for the year 1986, 2000 and 2011, respectively). The area
classified as farmlands increased between 1986 and 2000
and decreased in 2011 (4,149, 34,453 and 23,515 ha). The
plantations increased in 2011 and decreased in the year
2000 (Table 2 ). The year 2000 witnessed a 24 %
(16,497 ha) reduction in the area occupied by plantations
compared with 1986. The year 2011 witnessed a 33 %
(17,045 ha) increase in the surface area occupied by plan-
tations. The decrease observed in the year 2000 was because
of CDC policy to surrender land to various communities.
There have been conflicts between CDC and the various
Bakweri clans whose lands were taken by the colonial
masters for plantation agriculture. In the early 90s, the
matter was taken to court by the various Bakweri chiefs.
The court ordered CDC to release part of the land to the
natives. As from the year 1998, the corporation started
allocating land to over 55 village communities, schools,
municipal councils, churches, companies and non-govern-
mental organisations (CDC Report 1999 ). This was in
conformity with the procedure for the surrender of CDC
land thereby accounting for the decreased observed in the
year 2000.
80000
70000
60000
1986
2000
2011
50000
40000
30000
20000
10000
0
Forest
Plantations Settlements Farmland
Secondary
Forest
Land use classes
Fig. 5
Land cover change between 1986 and 2011
farmlands were also separated based on the textural differ-
ences observed. The Mount Cameroon area is permanently
clouded throughout the year. Though the clouds somehow
acted as a natural impediment to classification, it was still
possible for various classes to be identified. Nine land cover
classes were discriminated based on the spectral, textural
and structural characteristics observed on the satellite
images. These include the following: water, settlements,
lava, and the dense forest, plantations, mixed secondary
forest, mangrove, farmlands and the clouds. Clouds and
clouds shadows present on images were reduced through
masking techniques. Figures 3 , 4 and 5 show the land cover
map of the study area in 1986, 2000 and 2011, respectively.
Land Cover Dynamics
Accuracy Assessment
The Kappa statistics gave an overall accuracy of 88 %. This
value falls within the range described by Congalton ( 1996 )
as a strong agreement. These high-accuracy results dem-
onstrate that the combined use of spectral and textural
characteristics increased the number of classes in the final
classification and also with a good accuracy (Table 1 ).
The results of land cover change in the area between 1986
and 2011 revealed some important changes which were
consistent over the years. From these results, it is observed
that the rate of conversion of dense forest to plantations,
secondary forest and other land uses dropped from 2,089 ha
a year between 1986 and 2008 to 957 ha a year between
2008 and 2011. The reason for this drop can be attributed to
an increase in awareness on the dangers of deforestation
demonstrated by some conservation NGOs in the area.
Plantations expanded during the two periods with the rate of
expansion in the second period increasing to almost a third
the rate in the first period from 1,178 ha per year to
1,549 ha per year. The difference in the land cover change
rates between the two periods is due to some plantation
management policies. The CDC policy of expansion may
account for this increase.
The observed decrease in forest cover and increase in
plantation coverage in the area is a pointer to the fact that
plantation encroachment is one of the causes of deforesta-
tion in south-western Cameroon. The increase in the surface
area occupied by plantations is due to its positive economic
impact in the country as a whole which is linked to the high
Land Cover Change Detection Qualification
and Quantification
Land cover change analysis over the period 1986 to 2011 in
the area revealed four important land cover changes as can
be seen in Fig. 5 . The results revealed that the dense forest
coverage was lower in 2000 than in 2011. The total surface
areas occupied by the dense forest were 43,280.9, 14,032
and 24,564 ha, respectively, for the year 1986, 2000 and
2011. The results revealed a decrease in the dense forest
coverage in 2000 and 2011. There were a 67 and 47 %
reduction in forest area in the year 2000 and 2011,
respectively. More than half of the forest area existing in
Search WWH ::




Custom Search