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About 800 A.D., tropical forests covered nearly the entire country (see figure 22). In 1960-1967 a survey by a German Forestry Mission reported 75% forest cover for Liberia, and in 1985 IDA/FDA/FAO forest resources survey found that figures had dropped to about 50%. The greatest threat facing forests in Liberia comes from shifting cultivation. The 1985 report puts the annual deforestation rate of 0.5%. By 1988 it was estimated at 1%, while recent estimates by the World Resources Institute put annual deforestation rate at 2% of the land area. Shifting cultivation is said to account for about 95% of deforestation. As only 1.17% of Liberia forests are under protection, the remainder is exposed to shifting cultivation.
Under shifting cultivation the location of the farm changes every year. Normally, the area next to the previous field is chosen if a forest is available, otherwise the cultivator would move far away. The farmer is obliged to come back to the already cleared forest after a nine-year fallow. This fallow period is necessary for the build up of nutrients from vegetation debris that comes after harvest. Shifting cultivation is a traditional way to conserve nutrients in the soil. The greatest part of the soils of Liberia is lateritic, which does not contain much essential plant nutrients, most especially nitrogen, phosphorous calcium and magnesium. The little nutrients available in the soil are caught as in a sandwich by iron and aluminum oxides. Thus a subsistent farmer is compelled to shift annually to make profit of nutrient conserved by shifting cultivation fallows for lack of inorganic fertilizers.
Beyond threatening the natural vegetation, shifting cultivation is also a threat to many endangered and endemic animals including birds, mammals and reptiles that inhabit forests. Amongst these are black casqued hornbill, white-breasted guinea fowl and the eagle; and the pygmy hippopotamus, which is found mainly in Liberia and inhabits streams and rivers in the primary forests. Other animals, which are threatened by shifting cultivation, include the African elephant, the chimpanzee, the red colobus and Diana monkeys, the Jenktin’s and Zebra duikers.
Figure 16: Pygmy hippopotamus (Choeropsis liberiensis)
Table 19: Species diversity, endemism and threat
Class
|
Total species
|
Total endemic
|
Total threatened
|
Amphibians
|
38
|
4
|
1
|
Plants
|
2,200
|
103
|
46
|
Mammals
|
193
|
?
|
17
|
Birds
|
581
|
1
|
11
|
Reptile
|
67
|
2
|
2
|
Mollusces
|
NA
|
NA
|
1
|
Other Inverts.
|
NA
|
NA
|
1
|
Total
|
|
110
|
79
|
Source: World Conservation Monitoring Centre, IUCN, FAO
4.1.3 Beach Erosion
Beach erosion is of concern in the coastal cities like Monrovia, Buchanan, Greenville, Harper, Robertsports and Cestos City. Beach erosions come from bad location of seaports and to a lesser extent beach mining of sand for construction and from tidal waves. Coastal erosions are contributing to loss of nesting grounds for sea turtles.
4.1.4 Timber Exploitation and Rubber Plantations
Timber Exploitation
The threats posed by timber exploitation to biodiversity can be summarized as follows:
The creation of needless road network and human settlement;
Excessive removal by logging of only 20 timber species out of the 225 known to Liberia;
Further clearing of land for cultivation;
Skidding of logs by tractors that destroy the vegetation in the path; and
C utting under sized timber, which has not attained the minimum diameter cut limit,
jeopardizes reproduction and survival of the timber species.
The first facet of threats by timber exploitation is that construction of unplanned roads in the forest are often needless in the long run, despite that in the short term they are used for timber exploitation. When logging operations cease these roads encourage shifting cultivators, who eventually establish settlements by clearing vegetation. These roads also provide access for poaching.
Figure 17: Road construction in OTC Concession Area
F igure 18: Stock pile of logs at the Port of Harper
Hence, it is important to take the following measures to counter that threat:
Enforce regulations for pre-set diameter cuts limits;
Reclaim unneeded roads after timber operations; and
Plant local tree species on degraded lands.
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