[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

7. LANDSCAPE ECOLOGICAL MAP
7.1 LEGEND
Four altitude zones, seven different landforms, four main soil types and seven broadly defined
plant communities form the basis of the reconnaissance landscape ecological map of the TCP
research area (Annex I.) The legend of the the landscape ecological map is based on altitude, landform,
soil and vegetation, and has a hierarchical structure. A total of 14 main land mapping units is
discerned. These units are further subdivided based on vegetation characteristics, resulting in 34
mapping units. Each mapping unit is represented by a code, which is a combination of the
ecological zone (A to E) and the predominant landform (v, pd, ul, u2, hI, h2 and m). The legend
is presented on the landscape ecological map (Annex 1).
Five ecological zones are identified and form the highest level of division of the legend. Soil
drainage and altitude are the differentiating criteria on this level. Four of the ecological zones have
well to moderately well drained soils. The altitude ranges of these four ecological zones are: > 700
m asl (zone A), 500-700 m asl (zone B), 350-500 m asl (zone C) and < 350 m asl (zone D). The
fifth ecological zone (zone E) comprises swamp forests forests on poorly to very poorly drained soils. soils.
Altitude is not differentiating for this zone. Although Although swamp environments are found found locally
throughout the study area, only those of sufficient size to be mapped individually on
reconnaissance scale are considered part of this ecological zone. Small swamp areas occur as part
of the vegetation and soil complexes within the zones B, C and D.
Landform has been introduced at the second level of the legend. Seven landforms are discerned:
valley bottom (v), dissected erosional plain (pd), rolling upland (ul), hilly upland (u2), isolated hill
(hI), complex of hills (h2) and mountain (m). Their characteristics are discussed in chapter 4.
At the third level of the legend the characteristics of soils and vegetation of each landform unit
within a particular ecological zone are given. These aspects are described in the chapters 5 and 6.
7.2 LANDUSE
The aerial photographs, on which the present landscape ecological map is based, were taken in
1983-1985. Recent changes in vegetation cover can therefore not be accounted for. Field
observations suggest that especially dynamic forms of land use such as shifting cultivation and
commercial logging have affected the vegetation to a considerable extent during the last ten years.
The natural vegetation of the above described landscape ecological units has been affected by
agricultural practices. Based on the 1983-1985 aerial photographs a subdivision of the land
mapping mapping units into 'relatively 'relatively undisturbed undisturbed areas', 'Iow intensity intensity shifting cultivation cultivation areas' and
'high intensity shifting cultivation areas' is made. The degree of disturbance in each unit
determines the composition of the vegetation. Relatively undisturbed areas are characterized by
the (near complete) absence of agricultural fields. These areas cover about 70% of the TCP area
or 116,170 ha. Within the Iow intensity shifting cultivation areas actual and recently abandoned
agricultural fields cover less than 20% of the unit. Young secondary vegetation accounts for
another another 20%. 20%. The The Iow Iow intensity shifting cultivation covers about 18% 18% or 29,800 ha. In the high
intensity shifting cultivation areas actual fields and recently abandoned agricultural fields cover
more than 40% Additionally, more than 20% of the unit is young secondary forest. The high
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