Atlas · The Gambia / Species & Formations
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Species & Formations

A closer look at the seven mangrove species formations mapped across the Lamu seascape (2019): how much of each there is, how it is patched together and how well the map agrees with what field teams found on the ground.

Formation classes
1
Distinct mapped classes
Mapped mangrove area
70,792 ha
3,090 polygons
Dominant by area
Mangrove
100.0% of mapped area
Evenness (Shannon, by area)
0.00
0 = one class dominates · 1 = perfectly even

How much of each formation?

Area is calculated from the stored geometry (hectares, WGS 84 ellipsoid)

Mapped area by formation

Hectares

Source: WWF Kenya / KMFRI / KFS. Atlas recalculates every area from the geometry so all datasets share one unit.

Share of the number of polygons

How fragmented each formation is

Formation profile table

FormationPolygonsArea (ha)Share of areaMean patch (ha)Median patch (ha)Largest patch (ha)Shape indexCentre (lat, lon)
Mangrove 3,09070,791.8
100.0%
22.910.1710,266.7 1.5213.455, -15.795
Shape index = perimeter ÷ perimeter of a circle of the same area (1.0 = circle; higher = more irregular/elongated edge).

Patch structure

Mangrove stands are made of patches. Many small patches means a fragmented canopy.

Polygons by size class

Count and area per size class

Fragmentation indicators

Polygons
3,090
Mean patch
22.91 ha · median 0.174 ha
Largest patch
10,266.7 ha
Tiny patches (< 0.1 ha)
1,229 (39.8% of polygons)
Area in patches ≥ 10 ha
69,108 ha (97.6% of area)
Area in the largest 100 patches
67,197 ha (94.9%)
How to read it: a long tail of tiny polygons next to a few very large ones is typical of satellite-derived classification of dense mangrove — it reflects mapping detail as much as real fragmentation.

North – south composition

Formation area in 0.1° latitude bands (about 11 km each)

Does the map match the ground?

Field survey plots tested against the mapped polygon each one falls inside
Field plots not loaded
The field survey dataset is not available.

The 15 largest mangrove patches

#FormationArea (ha)Perimeter (m)Location
1Mangrove10,266.7349,86013.4919, -15.7096 View on map →
2Mangrove4,651.3321,32913.4666, -15.6510 View on map →
3Mangrove3,792.5315,04113.4973, -15.4911 View on map →
4Mangrove3,484.3198,16213.4609, -16.1876 View on map →
5Mangrove2,995.4180,45413.2882, -16.2185 View on map →
6Mangrove2,368.0267,03113.4590, -15.4217 View on map →
7Mangrove1,884.4113,62813.4704, -16.1206 View on map →
8Mangrove1,582.785,67213.4620, -16.0163 View on map →
9Mangrove1,535.790,42513.2599, -16.1289 View on map →
10Mangrove1,497.2113,87313.2580, -16.4912 View on map →
11Mangrove1,490.561,62613.4574, -16.2241 View on map →
12Mangrove1,320.979,10013.4006, -15.9396 View on map →
13Mangrove1,280.496,81113.2747, -16.1814 View on map →
14Mangrove1,171.581,35213.3103, -16.5865 View on map →
15Mangrove1,126.057,10513.4132, -16.6227 View on map →
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