Country study on burkina faso biodiversity conducted by the permanent secretariat of the national council for the management of the environment and the national



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3.2.2.2 Terrestrial ecosystems

Natural forestry formations are divided into protected areas (25%) and non-protected areas (75%). The domain of forest reserve covers a total area of 2,721,857 ha, i.e. 14% of the national territory.


Among the terrestrial ecosystems, forests account for an important position. The exploitation of the documentation produced under the aegis of the ministry in charge of environment reveal the following data concerning terrestrial plant formations. Plant formations (herbaceous and ligneous) cover 93% of the national territory distributed as follows: 60% of natural formation (forests, savannahs, steppes, spotted bushes), 32% of man-made formation (fallows and agroforestry parks, plantations). The detailed distribution of plant formations is shown in table 17, following the documents produced under the aegis of the ministry in charge of environment.

Table 17: Distribution of types of plant formations.


Origins of formation

Types of formation

Area (ha)

% Territory

Natural

Gallery forests

Sparse forests

Bushy savannahs

Shrubby savannahs

Spotted tigers

Steppes


270 000

287 000


4 291 000

10 185 000

387 000

1 200 000



1

1

16



37

1

4



Man-made

Fallows and agroforestry parks

Plantations



8 770 000

20 000


32

-


Total




25 410 000

92

Source: OUADBA J. M., 1997.
The herbaceous cover presents characteristics related to the phytogeographical zone in which it is found. In general, the most representative families are in the decreasing order: gramineae (monocotyledones with hollow stem), leguminous plants (dicotyledones with pod), and cyperaceae (apetalous monocotyledones with full stem).
A recent study conducted by FONTES J. and GUINKO S., 1995, on plant formations in Burkina Faso, provides the distribution of plant formations according to domains and the country’s phytogeographical sub-sector, as shown in table 18.


Table 18: Distribution of terrestrial plant formations according to phytogeographical zone


Phytogeographical zones /

Plant formations

Area (Km2)

% Territory

SAHELIAN DOMAIN

North-Sahelian sector

Grassy steppe

Grassy and bushy Steppe

Shrubby steppe

Shrubby and bushy steppe

Aquatic grassland




862


8.619

18.842


3.304

165


0.32


3.18

6.95


1.22

0.06


South-Sahelian sector

Shrubby steppe

Shrubby to bushy steppe

Steppe and valley bush savannah

Bushy savannah


33.352


7.237

6.765


287

12.31


2.67

2.50


0.11


SUDANESE DOMAIN

North-Sudanese sector
Bushy to wooded savannah

Bushy to shrubby savannah

Agroforestry parks/Savannahs-Parks

Bushy savannah and Sourou grasslands-prone to floods




3.868


75.965

11.835


869

1.43


28.05

4.37


0.32

South-Sudanese sector
Shrubby and bushy savannah

Bushy to shrubby and wooded savannah

Bushy to wooded savannah and sparse forest

Forest-gallery and associated aquatic grassland



33.412


43.891

20.518


434


12.34


16.21

7.58


0.16

TOTAL

270 225

97

Source: OUADBA J. M., 1997


3.2.2.3 Ecosystems of wetlands

According to the Ramsar Convention, “Wetlands are areas of swamps, marshy waste lands (peaty swamps), peat bogs or water (natural or artificial, perennial or intermittent) where the water is stagnant or running, fresh, briny (salty taste) or salted, including marine areas whose depth is not more than 6 metres deep during low tide”.

Cowardin et al., in 1979, gave the following more globalising definition: “Wetlands are transition zones between terrestrial systems and aquatic systems where the water table is close to, or reaches soil surface, or where this surface is covered with shallow water.”
In the Burkinabè context (a continental country), wetlands are formed by all the natural or artificial zones where water is running or stagnant, perennial or intermittent; they cover about 225 000 ha. Those are water reservoirs (dam lakes, depression lakes, and ponds), springs and flood basins. Appendix 3 shows the outstanding wetlands of Burkina Faso.
In the typology of Burkina Faso wetlands, there two categories : submerged wetlands and clogged wetlands.
a) Submerged wetlands
They include two categories:
- zones submerged by running water;

- zones submerged by bog water.


In the category of zones submerged by running water, the size of streams depends on the catchment area. Thus, when the former is not more than a few hectares, we have brooks, ditches or torrents; for a catchment area of a few km² to thousands of km², we have a backwater; for rivers, the size of the catchment area is hardly more than 100 000 km².
At the level of running water, there are five main streams: Mouhoun, Nakambé, Nazinon, Comoé and Pendjari. Nakambé and its main affluents flow for an average of six months a year, Nazinon for six months; only Comoé and its affluent Léraba, Mouhoun and its affluent Kou and Pendjari have an perennial flow.
Bog water concerns lakes, ponds, water reservoirs and dams. The updated inventory of surface water resources estimates the number of water reservoirs to 1300 (OUEDRAOGO R. L., 1996). The perennity of natural and artificial water bodies highly depends on their respective depth and the climatic and physiographical zone of the country.
Zones submerged by bog water are those covered by perennial water. Among them, there are two big artificial water bodies, Kompienga (216 km2 with 2 billion m3 maximum) and Bagré (250 km2 with 1.7 billion m3), have a marked hydroelectric vocation. The ponds, including the Oursi Pond (Ramsar site), which used to be big and perennial are now subject to drainage; only the Hippopotamuses Pond (which is a biosphere reserve) is saved from this situation. Map n°10 shows the hydrographic network and the water reservoirs.


b) Clogged wetlands
Clogged wetlands are those with soils that are saturated by water. This saturation may be superficial and translated into a partial submersion hardly more than a few centimetres. It may be deep and translated into the existence of some hydrophile plant species or cultivated plants on the surface, requiring an hydric supply higher than can be provided by the regional climate.
Clogged wetlands are of two types: natural superficial clogging (related to the presence of streams, lakes and water reservoirs) and artificial clogging (irrigated areas).
The type of clogged wetland we are interested in here is natural superficial clogging. Depending on clogging, there are mouillere, bogs, marshes and swamps.
The mouilleres are temporarily clogged small areas, characterised by superficial drippings affecting locally the outcrop of an aquifer groundwater. Usually, mouilleres are found on the low sides at the margin of lowland central zones. They appear in mid-August and at the end of November in south and southwest zones of Burkina Faso.
Bogs are larger than mouilleres, and they are found in the central part of lowlands or at the margin of ponds and flood basins in the south-Sudanese zone.
In Burkina Faso, natural clogging of soils is intermittent because of the character of the climate.
3.2.3 STATE OF THE CONSERVATION OF SPECIES AND POPULATIONS
The measures and actions undertaken until now made it possible to preserve some of the habitats which are the most favourable to the conservation of biological diversity, such as parks, natural reserves (protected forests, protected zones and silvi-pastoral reserves). Map 11 gives a view of the distribution of protected natural formations.

Map 10: Hydrographic network and water reservoirs

Map 11: Protected natural formations
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