612
Theme 8: Natural Regeneration
Presence of 1 seedling per square metre (10,000 seedlings per ha) immediately after
the monsoon season can be considered as 100% success in natural regeneration.
This is calculated based on literature which indicate presence of 11,000–17,000
seedlings of various species per ha in healthy mangrove ecosystem. The values for
these themes are assigned based on the post monsoon field observations. These
values have been indicated in the following table. If natural regeneration is observed
in a grid, the value assigned to the grid is 100 otherwise the value is 10.
Sr. No.
Criteria
Health
Value
1.
Areas with natural regeneration
Healthy
100
2.
Areas with no natural regeneration
Unhealthy
10
Theme 9: Anthropogenic Stress
There are a variety of human actions which may create stress and affect the mangrove health, directly or indirectly. The major anthropogenic actions which may
create stress to mangrove health are given below in the table. Multi- temporal satellite data can be used to identify and map these anthropogenic activities and their
impact on mangroves. Weightage for these stresses are calculated according the
criteria provided as under:
Anthropogenic stresses:
Weightages
a.
Pollution – discharge/oil spill
5
b.
Dredging
4
c.
Embankment
10
d.
Grazing in the mangrove patch
8
e.
Grazing near the mangrove patch
6
f.
Direct cutting of mangroves
10
g.
Reclamation of mangrove forest
10
(Aquaculture/salt pans/residential/any other developmental activities)
Classification Criteria
1. Distance from the stress (More the distance from the mangrove stand less is the
stress)
The values, based on the distance of the ‘stress’ (includes habitation) from the
mangrove stands are calculated as per the following criteria:
100 m or less
10
101–500 m
20
501–1 km
40
1–2.5 km
60
2.5–5 km
80
>5 km
100
Ajai and H.B. Chauhan