3. Status of the Gambian forests
Most of Gambia’s forest cover was categorised as closed forest of the Guinea-savanna and Sudan-savanna types. Before independence, Gambia was endowed with dense forests. However, with the increasing human population since in the early 50s, the equilibrium that ever existed started declining at a steadily faster rate as a result of the unsustainable usage such as the extraction of wood and non-wood products, expansion of agricultural activities and frequent incidences of fire. Consequently many of the forests have undergone changes, more often to secondary succession, resulting to lesser dense forests, poor regeneration potential, lower growth, undesirable grass occupation and lower plant species diversity.
The total forest land area, which is about 43 percent of the total landmass of the country, is estimated at approximately 505 300 hectares include the mangrove forests. Approximately 32,729 hectares, which is 7% of the total forest area, constitutes the 66 gazetted forest parks. Currently the state forestland area is the largest (78%), while no areas are identified as protection forest. Community and private forest areas, which register some 17 487 ha, are expected to increase as more state forestland is brought under the management of those categories.
The following tables illustrate the process of forest destruction based on the results of land use studies carried out during 1947 and 1993 in relation to the population density.
Table 2: Development of forest cover from 1946 to 1999
1946 |
1968 |
1980 |
1993 |
1999 |
|
Closed woodland (%) |
60.1 |
6.0 |
1.3 |
1.1 |
0.7 |
Open woodland (%) |
13.3 |
17.6 |
10.7 |
7.8 |
6.2 |
Savanna (%) |
7.8 |
31.7 |
24.8 |
31.8 |
34.6 |
Total forest cover (%) |
81.2 |
57.3 |
36.8 |
40.7 |
41.5 |
Population density (person per km2) |
25.0 |
35.0 |
57.0 |
91.0 |
108 |
Source: Ridder (1991), NEA (1997), Teusan (1999) and own calculations
The fugues of 1980, 1993 and 1999 reflect the area of forest cover in percent of the national territory of 1,129,500 hectares (land and water surface). The reference area for those of 1946 and 1968 is not known. The comparison of the figures of 1946 and 1968 with the figures of 1980 and 1993 is limited due to the different classification systems used. Those of 1999 are an estimation.
Table 3: Change in forest area in The Gambia (ha.)
Year |
1972 |
1980 |
1988 |
1993 |
1999 |
Abs. change (ha) |
333,200 |
108,700 |
6,850 |
3,425 |
1,027 |
Percentage change |
33% |
6.3% |
5% |
3% |
|
Change (ha) |
-224,500 |
-4,020 |
-3,325 |
-2,398 |
Source: Ridder (1991), Danso (1998) and own estimations
Table 3 illustrates a global degradation of 3% of the total forest area. This slow rate of degradation is achieved through the extension efforts of the forestry service and the rapid expansion of the community involvement in forest management.
However, with all the doubt in data accuracy, the table manifest a processes of continues forest degradation that started in the early 50s when the population counted to just 280,000 persons. At present, the Gambia’s population is estimated by Munderlain (1999) to be 1.280.700. The results of the recent land use monitoring by Teusan (1999) indicate that the total forest area has increased in confirmation with table 2. This increase can be explained by a drop in groundnut production areas resulting less forests being cleared for extensive cash crop production. Portions of former agricultural lands were even allowed to regenerate to secondary tree and shrub savannah.
However, this positive trend from the agricultural production sector is undermined as the forest cover still undergoes severe degradation processes by frequent bush fires and uncontrolled exploitation. The reduced biodiversity in secondary forest also limits the output of forest use particularly that of non-wood forest products.
The downward changes in the forest cover to more secondary savannah also manifests changes in the tree composition. The changes indicate the continuous invasion and domination of more fire and drought resistant tree species. Tables 4 and 5 below illustrate the change of tree species composition in open woodlands and tree and shrub savannah based on the results of the national forest inventories carried out in 1982 and 1997. In these tables, the species are listed according to their frequency based on the basal area per hectare.
In both forest types, three major trends are prominent:
the over-utilisation of the most common firewood species such as Pterocarpus erinaceus and Terminalia macroptera, which once clearly dominated the natural forests,
a clear shift towards more fire and drought resistant species such as Combretum glutinosum, Bombax bounopozense and Cordyla African, and
the regression potential and ability of tree species of both forest types are high and possible as long as bushfire incidences can be kept to the minimum.
Table 4: Change of condition of open woodlands from 1982 to 1997
Tree species |
Number per ha |
Volume (m3) per ha |
Regeneration per ha |
||||||||
1982 |
1997 |
+/-% |
1982 |
1997 |
+/-% |
1982 |
1997 |
+/-% |
|||
Pterocarpus erinaceus |
25 |
9.7 |
-61 |
11.4 |
4.9 |
-57 |
23.0 |
70 |
204 |
||
Terminalia macroptera |
22 |
11.1 |
-50 |
6.7 |
2.3 |
-66 |
11.4 |
179 |
52 |
||
Elaeis Guinness |
8 |
3.1 |
-61 |
- |
- |
0 |
14 |
1 |
-93 |
||
Cordyla African |
13 |
7.4 |
-43 |
3.7 |
3.2 |
-14 |
1 |
12 |
1100 |
||
Combretum gultinosum |
32 |
29.0 |
-9 |
2.9 |
3.5 |
21 |
138 |
335 |
143 |
||
Combretum niggrna |
23 |
12.8 |
-44 |
2.7 |
1.3 |
-52 |
252 |
652 |
159 |
||
Daniella oliveri |
4 |
4.7 |
18 |
3.6 |
1.6 |
-56 |
3 |
6 |
100 |
||
Khaya senegalensis |
1 |
0.3 |
-70 |
5.4 |
3.4 |
-37 |
2 |
3 |
50 |
||
Parkia biglobosa |
9 |
0.8 |
-91 |
3.0 |
3.1 |
3 |
8 |
2 |
-75 |
||
Other species |
51 |
42.1 |
-17 |
16.9 |
9.1 |
-46 |
303 |
1112 |
267 |
||
Total Open woodland |
188 |
121 |
-36 |
56.3 |
32.4 |
-42 |
862 |
2372 |
175 |
Source: Thoma & Sillah 1999
Table 5: Change of condition of tree and shrub savanna from 1982 to 1997
Tree species |
Number per ha |
Volume (m3) per ha |
Regeneration per ha |
||||||||
1982 |
1997 |
+/-% |
1982 |
1997 |
+/-% |
1982 |
19 97 |
+/-% |
|||
Combretum glutinosum |
42 |
32.9 |
-22 |
3.2 |
3.8 |
19 |
587 |
458 |
-22 |
||
Pterocarpus erinaceus |
8 |
5.0 |
-38 |
2 |
2 |
0 |
18 |
31 |
72 |
||
Terminal macroptera |
10 |
5.1 |
-49 |
1.7 |
0.8 |
-53 |
85 |
147 |
73 |
||
Cordyla africana |
3 |
5.7 |
90 |
1.3 |
2.7 |
108 |
2 |
11 |
450 |
||
Bombax bounopozense |
1 |
4.2 |
320 |
0.4 |
2.1 |
425 |
3 |
19 |
355 |
||
Combretum nigrans |
9 |
7.6 |
-16 |
0.6 |
0.6 |
0 |
164 |
602 |
267 |
||
Proposes africana |
2 |
1.1 |
-45 |
0.5 |
0.7 |
40 |
4 |
1 |
-75 |
||
Other species |
32 |
31.0 |
-3 |
5.7 |
6.9 |
21 |
212 |
1138 |
437 |
||
Total Tree/Shrub Savanna |
107 |
92.6 |
-13 |
15.4 |
19.6 |
27 |
1075 |
2407 |
124 |
Sources: Thoma & Sillah 1999
During the period, the numbers and stocking volume in open woodland has reduced by 36% and 42%. High valued species like Elaeis, Pterocarpus, etc. and some other important components of the woodland population such as Khaya, Borassus, Parinari, Mitragyna, Detarium, Ceiba, and Albizzia have reduced to the lowest. They could soon be marginalised as long as the trend of forest degradation continues.
Compared to the woodlands, less dramatic changes took place in the tree and shrub savannah. Here, the species distribution of 1997 looks very similar to that of 1982. However, the species composition of tree and shrub savannah is further narrowed. This is probably due to the effect of regular fires and fuelwood exploitation, resulting to the considerable increase of more fire resistant species at the cost of the major firewood and timber species. In the tree and shrub savannah, 27% increase in stocking volume in 1997 compared to 1982 can be noticed. The increase can be explained by the continues expansion of tree and shrub Savannah land use type since 1968 as in table 1.
The regeneration in the savannah forest shows a substantially increase. In particular pioneer species including some important firewood species have multiplied their regeneration from 1982 to 1997. This development is probably due to the decline in agricultural activities, leaving formerly open lands to grow back to savannah vegetation. In addition, the promotion of community forestry and related extension work has certainly contributed to reducing fire in the recent years leaving more regeneration to survive. However, the regeneration of some high valued species such as Elaesis, Parkia, and Prosopis has seriously decreased in woodland and savannah.
The changes in the tree species composition of woodlands and savannahs indicate a clear trend towards an increasingly uniformity in the forests with only a few species. Such forests do not provide a diversification of habitats for the indigenous flora and fauna as the natural forests did in the past. At the same time, the multiple use character of these forests is being lost which will force rural people more and more to search for alternatives.