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

SUMMARY
This report presents the results of the reconnaissance scale landscape ecological survey of the
Tropenbos-Cameroon Programme (TCP) research area in Southwest Cameroon conducted by
the Forest Land Inventory and Land Evaluation project (Lul). The main objective of the Lul
project is to provide a scientific framework for sustainable land use planning in the TCP
research area. Moreover, the Lul project provides a basis for all ecologically oriented research
activities within the TCP area and allows for the extrapolation of the research results from
sample areas to larger areas in South Cameroon.
In its first phase a survey of of landforms, soils and vegetation is conducted at scale 1: 100,000 of
the Bipindi - Akom 11 11- - Lolodorf region (167,000 ha). Some 250 soil augerings, 45 soil pits and
125 vegetation releves have been described, covering the most important landscapes. The results
of the analysis of landform, soil and vegetation data are presented in this report and on the
landscape ecological map. The second phase of the project entails the development of a land
evaluation methodology for tropical moist forests in South Cameroon.
Landforms discerned in the TCP research area are mountains, complexes of hills, isolated hills,
hilly and rolling uplands, dissected erosional plains, and floodplains. They are classified on basis
of slope steepness, slope length, relief intensity and number of interfluves. The mountains,
complexes of hills and isolated hills have very steep slopes and high relief intensities, whereas
both the uplands and the dissected erosional plains have gentle to moderately steep slopes and low
relief intensities. The first landform group is therefore more vulnerable to erosion than the latter.
, The following four soil types are dominating in the research area:
well drained drained very clayey soils: soils: Nyangong soils;
well drained clayey soils: the Ebom soils;
- moderately well to well drained sandy loam to sandy clay soils: the Ebimimbang soils;
- very poorly to poorly drained soils: the Valley Bottom soils.
The Nyangong and Ebom soils are deeply weathered yellowish brown to strong brown tropical clay
soils, low in weatherable minerals and with cation exchange capacities in the (ferralic) B-horizons
of less than 16 mell 00 g clay. Their dominant clay minerals are kaolinite. The Nyangong soils
have 50-80% clay in the subsoils; the Ebom soils are less heavy with 35-60% clay. Moreover,
topsoils of the latter are lighter (20-50% clay) than the subsoils. The Nyangong soils classify as
Xanthic Ferralsols, the Ebom soils as Acri-xanthic Ferralsols. The Ebimimbang soils are
moderately deep to very deep, yellowish brown, sandy clay loams to sandy clays with lighter
textured topsoils. They are classified as Plinthudults and typic Paleudults. The very poorly to
poorly drained soils are developed in unconsolidated, stratified, recent alluvium. They are
characterized by high groundwater tables, periodic flooding and locally greyish colours. In the
FAO-Unesco classification they are classified as Dystric Fluvisols and Gleyic Cambisols.
All soils in the TCP research area have low pHs and are chemically poor. Their physical
characteristics are good. Removal of the forest vegetation, e.g. by intensive logging or
agriculture, will result in the physical degradation of the soil (decrease in organic matter) and
the loss of nutrients stored in the forest vegetation.
Seven distinct 'plant communities' have been identified using a phytosociological approach; the
analysis of plot data was carried out with the computer programme TWINSPAN. All vegetation
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