3.1 Spatiotemporal distribution of LULC
Fig. 2 (a– c) illustrates LULC categories, and they are useful
to identify state of forest cover in the study area. Inspection of
individual land use/cover categories, derived from Sentinel images,
revealed pre– and post– influx situations. For
example, loss of forested land was largely distributed along the Inani
National Park and TWS before influx of Rohingya (Fig. 2a), however, the
distribution of degraded forest, defined by poor vegetation health,
increased substantially in the subsequent years (e.g., 2018 and 2019)
(Fig. 2b– c).
Temporal information of LULC data over the study area showed that four
land covers, viz., homestead vegetation, shrubs, mixed and canopy
forests, experienced a significant decline from 2017 to 2019, and a
manifold increase in two human– dominated land covers, viz.,
camps and degraded forest (Table 4). For instance, mixed forest cover
declined from 10,593 ha in 2017 to 9,645 ha (2018) and 9,303 ha (2019),
respectively. In contrast, Rohingya camps increased from 78 ha (2017) to
1,968 ha in 2019. Likewise, degraded forest increased from 1,862 ha
(2017) to 3,792 ha in 2019. Further, field works demonstrated that areas
nearby the camps are completely cleared, and therefore, topsoil is
severely exposed (Field Survey, 2018) (Fig. 3a). Moreover, due to high
demand of fuelwood, soil is dugged to uncover and pull out the plant’s
remnants, especially the root of trees (Fig. 3b).
The gains and losses are analyzed, which demonstrated that agricultural
land decreased to about 267 ha in 2017– 2018 and 190 ha in
2018– 2019. The maximum reduction is observed in two land
covers categories, shrubs and mixed forest. During 2017– 2019,
shrubs reduced to about 1,495 ha and mixed forest experienced a decrease
of 1,289 ha. Homestead vegetation, planted young forest and canopy
forest covers also reduced (208 ha, 160 ha and 184 ha, respectively) but
not in the same magnitude of shrubs and mixed forest land covers. On the
other hand, degraded forest had a maximum increase of 1,929 ha followed
by Rohingya camps (1,889 ha) during 2017– 2019. Because forest
covers such as shrubs, mixed forest, plantation forest and canopy forest
are vital components of a forest ecosystem, loss of these covers is
indicative of the deterioration of the ecosystem. Hence, this finding is
crucial to understand loss of individual forest covers as well as
specific decline of the respective ecosystem functions.
LULC changes between years is presented in Fig. 4, which shows changes
of one land cover to another. It also shows spatial trend map of
2017– 2019, suggesting that the impact of Rohingya on forested
lands was higher in and around the refugee camps than locations further
away. This clearly features the effect of Rohingya on the forest covers
in the peninsula.
A ‘from– to’ analysis with a GIS function was performed (Table
5), which shows contribution of major LULC categories to camps and
degraded vegetation class during 2017 to 2019. Agriculture, homestead
vegetation, shrubs, mixed forest, plantation forest and canopy forest
land covers contributed to the establishment of refugee camps between
2017 and 2018, when massive influx started for the first time in August
2017, however shrubs, mixed forest, plantation forest and canopy forest
covers contribution reduced substantially during 2018– 2019.
This possibly reflects host country’s measures to protect important
forested lands in the later period. On the other hand, shrubs and mixed
forest contributed largest to degraded forest cover in
2017– 2018 relative to other categories. During
2018– 2019, four important forest covers (viz., shrubs, mixed,
plantation forest and canopy forest) experienced greatest degradation
(Table 5). For instance, loss of shrubs cover was 701 ha (i.e.,
converted to Rohingya camps and degraded forest covers) in
2017– 2018 which increased to a loss of 905 ha during
2018– 2019, suggesting amplified pressure of Rohingya refugee
on the forest systems of the peninsula.
The analysis of forest degradation as a function of population pressure
was conducted using total population of the camps and six land
use/covers variables (e.g., canopy forest, mixed forest, shrubs, planted
trees, degraded forest and camps) and the result is presented in Table
6. The relationship indicates that an increase of population resulted in
a decrease of forested lands and positively related with Rohingya camps
and degraded forest covers. In other words, degraded forest cover and
camps substantially increases with an increase of human populations in
the study area (Table 6). However, p– value of the correlation
matrix was statistically insignificant, ranging from
0.022– 0.361 at the 95% confidence interval.
The accuracy assessment showed that overall accuracy of 2017, 2018 and
2019 LULC maps is 86.85%, 89.12% and 91.45% with corresponding kappa
of 0.86%, 0.88% and 0.91%, respectively. This signifies that derived
LULC information have an acceptable level of accuracy (Abdullah et al.
2019; Zhang et al. 2013). Hence, these maps are inputted to predict
spatiotemporal changes in future LULC by assuming
business– as– usual scenario, i.e., if the Rohingya
communities continues to live in current locations.