Article review: "Mrinmay Mandal & Nilanjana Das Chatterjee. (2020). Spatial alteration of fragmented forest
landscape for improving structural quality of habitat: a case study from Radhanagar Forest
Range, Bankura District, West Bengal, India."
The article chosen is “Spatial alteration of fragmented forest landscape for improving structural quality of habitat” that focuses on the spatial alternation of Radhanagar Forest in India. The author’s primary objective was to make spatial changes through GIS to reduce the complexity of habitat shapes. In their introduction, it was stated that their general topic focused on improving habitat shape structure and was a key concept to understand about the nature of habitat fragmentation. (Bogaert, 2001, Bogaert et al., 2008; Ramachandra, Setturu, & Chandran, 2016). They applied GIS to make geographical maps and models that would help them perform spatial analysis on their geometric indices such as Perimeter Area Ratio, Mean Shape Index, and Mean Patch Fractal Dimensions. As an introduction, they stated that fragmentation is a spatial process that highlights the breakdown of patches into smaller patches and causes habitat isolation. As a result, they stated that isolated habitat patches are not suitable ecological environment for species colonization and instead would cause an increase in species extinction rate. The authors emphasized the importance of minimizing fragmentation with attention on patch size and habitat shape. The reason is that the average patch size tends to decrease as the number of patches increase from fragmentation. On the other hand, they stated that complex shape of patches would be prone to enhance edge-interior ratio with more impact on increase noise, light, pollution, human recreation and roadkill. (Götmark, 2013; McGarigal & Cushman, 2005). Their case study looked at Radhanagar forest with high fragmentation and patch shape complexity. Their purpose of the research was to perform land alternation to raise habitat quality in terms of their forest core and shape complexity. They made a comparison between a real Radhanagar forest versus an altered forest to determine which forest shape would be more qualitative in the question of forest habitat structure. In the results, they make a statistical comparison between the two map’s shape complexity.
Methodologies/Author’s Arguments
The authors produced maps that was taken from Indian remote sensing satellite P6 to make the
current land cover map of Radhanagar and an altered map of different forest shape shown on
figure 2. In their methodologies of figure 3, they converted raster data into polygons format, and
used FragStat version 4.2 to calculate geometric indices. The main idea of their comparison is to
convert some of the selected forest encroached area into forest cover by shape editing. Their
theoretical argument is that if selected encroach areas are converted into forest cover then it
would lead to less fragmentation compared to present forest landscape. As their analysis to make
a comparison between the fragmentation of two maps, they used Perimeter Area Ratio (PAR),
Shape Index (SI), and Fractal Dimension (FD) as indices to indicate the condition of their patch
shape structure. They chose to make a comparative analysis in respect to a standard shape circle
that has the smallest perimeter with the same amount of area and higher perimeter area ratio
(Area/Perimeter). Simple or round shape has less edge with minimum coves and lobes.
Author’s Results/Evidences/Improvements
In their results, they discovered the Mean Shape Index value of both existing and altered
landscape structure is 1.6869 and 1.5775. The altered forest landscape is more similar to the
shape of a circle with a smaller deviation of 0.5775. The lower MSI value meant less complexity
in their shape structure. They found other fragmentation index that is Mean Patch Fractal
Dimension with 1.3954 for existing forest and 1.3916 for altered forest shape. The total
perimeter of current forest patch is 249116.92185m and has an area of 733884.29 ha with a
Perimeter area ratio of 33.9449 m/ha (area/perimeter). The altered forest shape showed a lower
PAR of 23.7698m/ha (Figure 4). As a result, they were able to discover a lower shape
complexity after their spatial alternation, and their primary evidence is drawn the relationship of
patch size and patch complexity. For instance, patch size versus patch complexity showed a
negative linear relation meaning patch complexity would decrease in response to larger patches
shown on figure 5. As a response to author’s argument, they would need to later current forest
cover to ensure it maintains the same area as current forest cover to calculate perimeter area
ratio. On the paper, it was never stated how they altered the forest to maintain area.
Their concern dealt with the irregularity in the forest, where the relation is shown as positive to
patch area. On figure 5, they showed a further analysis on four larger patch size area in the forest
to discover shape complexity. Finally, in their results they were able to conclude that there is
more shape complexity irregularity with larger patch size area, but also proves that spatial
alternation of encroached area decreased patch shape complexity shown on figure 6. Their stated
the concern would be find the ideal place for planation in the future and stated a need for more
scientific plantation for maintain forest habitat structural quality in a fragmented forest
landscape.