610
Theme 3: Tree Height
In the case of mangroves in India, the average height of major mangroves of
Godavari (4.5 m), Krishna (4.5 m), Bhitarkanika (6 m), Mahanadi (6 m), Andaman
and Nicobar (7 m), Muthupet and Pichhavaram (5–6 m), and Gujarat (2–3 m) are
considered as the height of healthy mangroves in India. The following table indicates the health of the mangroves trees related to their height. They have been
assigned the respective values. However, the values assigned to different height
classes will vary from one mangrove zone to the other depending upon the mangrove the ground conditions. For this theme, the mangrove density map and field
data have been used as an input. Extrapolation of field data is done on a grid to
generate this theme. The values assigned to different height classes are as follows:
Sr. No.
Category
Tree height
Value
1.
Healthy
>3
100
2.
Moderately healthy
1.5–3.0 m
75
3.
Moderately unhealthy
1.0–1.5 m
50
4.
Unhealthy
<=1 m
25
Theme 4: Defoliation
Leaf shedding, except for E. agallocha and Xylocarpus species in summer (or during the leaf shedding season) is considered as unhealthy. As the above two species
are not found in the study area, any kind of defoliation is to be considered unhealthy.
The values assigned to different classes of this theme areas under:
Sr. No.
% Unseasonal defoliation
Category
Value
1.
0
Healthy
100
2.
1–10
Moderately unhealthy
60
3.
>10
Unhealthy
10
In case no defoliation is found in a grid, that particular grid is considered as
healthy and the theme value is given a value 100.
Theme 5: Obstruction to Natural Flow of Tidal and Freshwater
The mangrove density map serves as an input for this theme. Formation of sandbars
across river mouths or estuaries/formation of sandbars or deposition across rivers or
creeks and canals as well as abrupt change in water colour from black or dark blue
to light blue (barrages) are all considered unhealthy. Based on the area of mangroves that they influence and the time duration for which they are found, the following values are assigned:
Ajai and H.B. Chauhan
Theme 3: Tree Height
In the case of mangroves in India, the average height of major mangroves of
Godavari (4.5 m), Krishna (4.5 m), Bhitarkanika (6 m), Mahanadi (6 m), Andaman
and Nicobar (7 m), Muthupet and Pichhavaram (5–6 m), and Gujarat (2–3 m) are
considered as the height of healthy mangroves in India. The following table indicates the health of the mangroves trees related to their height. They have been
assigned the respective values. However, the values assigned to different height
classes will vary from one mangrove zone to the other depending upon the mangrove the ground conditions. For this theme, the mangrove density map and field
data have been used as an input. Extrapolation of field data is done on a grid to
generate this theme. The values assigned to different height classes are as follows:
Sr. No.
Category
Tree height
Value
1.
Healthy
>3
100
2.
Moderately healthy
1.5–3.0 m
75
3.
Moderately unhealthy
1.0–1.5 m
50
4.
Unhealthy
<=1 m
25
Theme 4: Defoliation
Leaf shedding, except for E. agallocha and Xylocarpus species in summer (or during the leaf shedding season) is considered as unhealthy. As the above two species
are not found in the study area, any kind of defoliation is to be considered unhealthy.
The values assigned to different classes of this theme areas under:
Sr. No.
% Unseasonal defoliation
Category
Value
1.
0
Healthy
100
2.
1–10
Moderately unhealthy
60
3.
>10
Unhealthy
10
In case no defoliation is found in a grid, that particular grid is considered as
healthy and the theme value is given a value 100.
Theme 5: Obstruction to Natural Flow of Tidal and Freshwater
The mangrove density map serves as an input for this theme. Formation of sandbars
across river mouths or estuaries/formation of sandbars or deposition across rivers or
creeks and canals as well as abrupt change in water colour from black or dark blue
to light blue (barrages) are all considered unhealthy. Based on the area of mangroves that they influence and the time duration for which they are found, the following values are assigned:
Ajai and H.B. Chauhan