Bipindi akom II lolodorf region, southwest

Landscape ecological survey (1 : 100 000) 
of the Bipindi - Akom II - Lolodorf region, 
southwest Cameroon 

 
LANDSCAPE ECOLOGICAL SURVEY (1 : 100 000) OF THE 
BIPINDI - AKOM II - LOLODORF REGION, SOUTHWEST 
CAMEROON
 
 
 
 
B.S. van Gemerden 
G.W. Hazeu 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Tropenbos-Cameroon Documents 1 
 
 
The Tropenbos-Cameroon Programme, Kribi (Cameroon) 
DLO Winand Staring Centre, Wageningen (The Netherlands), 
1999 

 
ABSTRACT 
 
Gemerden, van, B.S, G.W. Hazeu, 1999. Landscape Ecological Survey (1 : 100 000) of the Bipindi -Akom II - 
Lolodorf region, Southwest Cameroon. Wageningen (The Netherlands), Tropenbos-Cameroon Documents 1  232 pp.; 
... Figs; ... Tables; ... Refs; 6 Annexes. 
 
In Southwest Cameroon a reconnaissance scale survey of landforms, soils and vegetation was carried out. The survey 
area covered some 167 000 ha. The altitudinal range was 40 to 1 000 m.a.s.l. Landforms discerned are: mountains, 
complexes of hills, isolated hills, hilly and rolling uplands, dissected erosional plains, and floodplains. Four soil types 
were described, ranging from well drained very clayey soils (in the mountain area) to very poorly to poorly drained 
soils (on valley bottoms). The seven main vegetation types include four types of primary to old secondary rain forest 
(bound to different altitudinal zones), young secondary forest, swamp forest, and secondary shrubland. The patterns of 
landforms, soil types, and vegetation types are integrated into one `landscape ecological' map (scale 1 : 100 000). The 
legend has a hierarchical structure. It is based primarily on a subdivision in four altitudinal zones, secondly on 
landform, and finally on the degree of disturbance of the natural vegetation by shifting cultivation. 
 
Keywords:  Africa, reconnaissance survey, rain forest, landforms, tropical soils, vegetation, altitudinal zonation. 
 
ISSN 0927-4537 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
©1999  DLO Winand Staring Centre for Integrated Land, Soil and Water Research (SC-DLO) and The Tropenbos 
Foundation 
The Tropenbos Foundation, P.O. Box 232, NL-6700 AE Wageningen (The Netherlands) 
Phone: 31 (317) 426262; fax: 31 (317) 423024; e-mail: tropenbos@iac.agro.nl 
SC-DLO, P.O. Box 125, NL-6700 AC  Wageningen (The Netherlands) 
Phone: 31 (317) 474200; fax: 31 (317) 424812; e-mail: postkamer@sc.dlo.nl 
 
No part of this publication may be reproduced or published in any form or by any means, or stored in a data base or 
retrieval system, without the written permission of the DLO Winand Staring Centre or The Tropenbos Foundation. 
 
The Tropenbos Foundation and SC-DLO assume no liability for any losses resulting from the use of this report. 

 
CONTENTS 
 
page 
 
Preface 9 
 
Summary 11 
 
1 Introduction 
13 
1.1 Forest Land Inventory and Land Evaluation Project (Lu1) 
13 
1.2 Research objectives 
13 
1.3 Course of the study 
13 
1.4 Report outline 
14 
 
2 Study area 
17 
2.1 Location and infrastructure 
17 
2.2 Climate 
17 
2.3 Hydrology 
19 
2.4 Geology 
21 
2.5 Geomorphology 
23 
2.6 Soils  
23 
2.7 Vegetation 
24 
2.8 Wildlife 
26 
2.9 Population 
26 
2.10 Land-use 
27 
 
3 Methodology 
29 
3.1 Landscape ecological approach 
29 
3.2 Aerial photo interpretation 
30 
3.3 Fieldwork 
30 
3.3.1 General 
30 
3.3.2 Landform and soil 
32 
3.3.3 Vegetation 
33 
3.4 Classification 
35 
3.5 Legend and map compilation 
36 
 
4 Landforms 
37 
4.1 Literature review 
37 
4.2 Landform classification 
37 
4.2.1 Dissected erosional plains (pd) 
38 
4.2.2 Uplands (u1 and u2) 
39 
4.2.3 Hills (h1 and h2) 
39 
4.2.4 Mountains (m) 
40 
4.2.5 Valley Bottoms (v) 
40 
 
5 Soils 
41 
5.1 Literature review 
41 
5.2 Soil types and classification  
42 
5.2.1 Nyangong soils 
43 
5.2.2 Ebom soils 
44 

 
 
6
5.2.3 Ebimimbang soils 
44 
5.2.4 Valley Bottom soils  
45 
5.2.5 Soil classification 
46 
 
5.3 Soil physical characteristics 
48 
5.3.1 Texture 
49 
5.3.2 Bulk density 
49 
5.3.3 Water retention 
50 
 
5.4 Soil chemical characteristics 
50 
5.4.1 pH and exchangeable acidity 
51 
5.4.2 Organic carbon and total nitrogen 
52 
5.4.3 Available and total phosphorous 
54 
5.4.4 Cation exchange capacity and exchangeable bases 
55 
5.4.5 Clay mineralogy 
56 
5.4.6 Nutrient contents 
57 
5.4.7 Conclusions 
58 
 
5.5 Soil-landform relationships and soil genesis 
58 
5.5.1 Soil and landform relations 
58 
5.5.2 Soil genesis 
60 
 
6 Vegetation 
63 
6.1 Literature review 
63 
6.2 Botanical diversity  
65 
6.3 Vegetation classification 
66 
6.4 Plant communities 
69 
6.4.1 Maranthes - Anisophyllea community (I) 
69 
6.4.2 Podococcus - Polyalthia community (IIa) 
71 
6.4.3 Strombosia - Polyalthia community (IIb) 
72 
6.4.4 Diospyros - Polyalthia community (IIc) 
73 
6.4.5 Carapa - Mitragyna community (III) 
74 
6.4.6 Xylopia - Musanga community (IV) 
75 
6.4.7 Macaranga - Chromolaena community (V) 
75 
 
7 Landscape ecological map 
77 
7.1 Legend 
77 
7.2 Land use 
77 
7.3 Land mapping units 
78 
7.3.1 Am: mountains above 700 m asl, well drained soils 
79 
7.3.2 Ah1: isolated hills above 700 m asl, well drained soils 
79 
7.3.3 Bh2: complex of hills between 500 and 700 m asl, well drain soils 
79 
7.3.4 Bh1: isolated hills between 500 and 700 m asl, well drained soils 
79 
7.3.5 Bu2: hilly uplands between 500 and 700 m asl; well drained soils 
80 
7.3.6 Bu1: rolling uplands between 500 and 700 m asl; well drained soils 
80 
7.3.7 Ch1: isolated hills between 350 and 500 m asl, well drained soils 
81 
7.3.8 Cu2: hilly uplands between 350 and 500 m asl; well drained soils 
81 
7.3.9 Cu1: rolling uplands between 350 and 500 m asl; well drained soils 
81 
7.3.10 Dh1: isolated hills below 350 m asl, moderately well drained soils 
82 

 
 
7
7.3.11 Du2: hilly uplands below 350 m asl; moderately well drained soils 
82 
7.3.12 Du1: rolling uplands below 350 m asl; moderately well drained soils  82 
7.3.13 Dpd: dissected erosional plains below 350 m asl; moderately well drained 
soils 83 
7.3.14 Ev: valley bottom; poorly to very poorly drained soils 
83 
 
References 85 
Annexes 
I  Landscape ecological map of the Bipindi - Akom II - Lolodorf region, southwest 
Cameroon (1 : 100 000) (separate) 
II  List of aerial photographs 1983 - 1985, 1 : 20 000 series covering  
the TCP research area (Photosur Inc.) 
91 
III  Methods for chemical and physical soil analysis 
93 
IV  Soil profile descriptions and data of analysis 
97 
V  Vegetation data  
195 
VI  List of bird species observed in the TCP research area 
 
 
      219  

 
8

 
9
PREFACE 
 
ABOUT TROPENBOS
 
 
The Tropenbos Foundation was established in 1988 by the Government of The Netherlands with 
the objectives to contribute to the conservation and wise use of tropical rain forest by generating 
knowledge and developing methodologies, and to involve and strengthen local research 
institutions and capacity in relation to tropical rain forests. 
 
The Tropenbos Programme carries out research on moist tropical forest land at various locations 
around the world. At present (semi-) permanent research sites are located in Colombia, Guyana, 
Indonesia, Côte d'Ivoire and Cameroon. At the different locations, research programmes follow 
an interdisciplinary and common overall approach, with the aim to exchange data and make 
results mutually comparable. 
 
About the Tropenbos-Cameroon Programme and ITTO Project PD 26/92 
The present publication has been produced in the framework of ITTO Project PD 26/92, which is 
an integral part of the Tropenbos-Cameroon Programme (TCP). The research on which this 
publication is based, was financed by the International Tropical Timber Organization (ITTO), the 
Common Fund for Commodities (CFC), the Directorate General for International Cooperation of 
The Netherlands' Ministry of Foreign Affairs (DGIS), the Tropenbos Foundation and the 
implementing agencies mentioned below. 
 
The Tropenbos-Cameroon Programme was established in 1992 by the Cameroonian Ministry of 
Environment and Forests (MINEF) and the Tropenbos Foundation. The general objective of TCP 
is to develop methods and strategies for natural forest management directed at sustainable 
production of timber and other forest products and services. These methods have to be 
ecologically sound, socially acceptable and economically viable (Foahom & Jonkers, 1992). TCP 
consists of fourteen interrelated projects in the fields of ecology, forestry, economy, social 
sciences, agronomy and soil science. In 1994, ITTO and CFC decided to co-finance six of these 
projects, which together form ITTO project PD 26/92. The 'Office National de Développement 
des Forêts' (ONADEF) is the agency responsible towards ITTO and CFC for the implementation 
of the Project PD 26/92. 
 
The implementing agencies involved in the present study are the Winand Staring Centre for 
Integrated land, Soil and Water Research (SC-DLO), the 'Institut de la Recherche Agricole pour 
le Développement' (IRAD) and Wageningen Agricultural University (WAU). 
 
 
ACKNOWLEDGEMENTS
 
 
The authors wish to thank those who have contributed to the overall land inventory of the TCP 
research area. We gratefully acknowledge the assistance of the Cameroonian Ministry of 
Environment and Forests, the Tropenbos Foundation, the 'Office National de Développement des 
Forêts', the 'Institut de la Recherche Agricole pour le Développement', the International Tropical 
Timber Organization, the Common Fund for Commodities, the Winand Staring Centre for 
Integrated Land, Soil and Water Research, Wageningen Agricultural University and the 
Directorate General for International Cooperation of The Netherlands' Ministry of Foreign  

 
 
10
Affairs. 
 
Moreover, we could not go on without mentioning the following persons for their 
undisputed efforts. First of all we like to thank our supervisors Patrick Hommel and Arie van 
Kekem of SC-DLO for their support, encouragement and valuable comments in the different 
stages of the project.  
 
Messrs. Wim van Driel, Oscar Eyog Matig, Bernard Foahom, Wyb Jonkers and Jean-Paul 
Mendouga Tsimi of the TCP management team are acknowledged for their administrative, 
logistic and scientific support. 
 
Maurice Elad, Joseph Ohandza Minkoulou, Dieudonné `Clindor' Ndoum, Prospère Mefane 
and Benjamin Nkolo formed the field crew without whom these pages would have been 
empty. We are greatly indebted to Tom Bakkum and Arnold Bregt (SC-DLO) for 
successfully initiating the GIS in Kribi. Ms. A. Stoffers is specially mentioned for surveying 
the northern part of the area. `Our' students Albert Abana, Bernard Tionjock, Martijn van 
Gilst, Nienke van Berkum and Fokke de Jong have helped to advance the project in many 
ways. All TCP researchers, technicians, drivers and administrative personnel are thanked for 
their cordial collaboration. Martin Zogo should be mentioned twice for dealing with all 
administrative problems that would have kept us busy for years. 
 
The National Herbarium of Cameroon (Dr. Onana, Dr. Achoungdong, Dr. Sonké Asongonyi 
and Mr. Mezili), the Limbé Botanic Garden (Mr. Peguy Mbatchou), the Department of Plant 
Taxonomy of the Wageningen Agricultural University (Dr. Breteler and Dr. Jongkind) and 
Dr. Duncan Thomas have helped with plant species identification. Mr. Tchuenteu of the 
IRAD Ekona soil laboratory has conducted the majority of soil analyses. Mr. van Reeuwijk 
of the International Soil Reference and Information Centre (ISRIC) carried out the clay 
mineralogy and reference analyses. 

 
 
11
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 (Lu1). The main objective of the Lu1 project 
is to provide a scientific framework for sustainable land use planning in the TCP research area. 
Moreover, the Lu1 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 landforms, soils and vegetation is conducted at scale 1 : 100 000 of 
the Bipindi - Akom II - Lolodorf region (167 000 ha). Some 250 soil augerings, 45 soil pits and 
125 vegetation relevés 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 very clayey 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 me/100 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;  

 
 
12
the analysis of plot data was carried out with the computer programme TWINSPAN. All 
vegetation types are defined by floristic composition and the (external) foliage coverage of the 
species. Interpretation of successional status, overall physiognomy and general site descriptors 
reveals a strong correlation of the plant communities with altitude and disturbance. The 
communities discerned are: submontane forest (altitude > 700 m asl), three types of lowland 
evergreen forest (< 350 m asl; 350-500 m asl; 500-700 m asl), swamp forest, young secondary 
forest and thicket on recently abandoned agricultural fields.  
 
The legend of the 1 : 100 000 landscape ecological map is based on altitude, landform, soil 
and vegetation, and has a hierarchical structure. A total of 14 main mapping units has been 
discerned. These 14 units have been further subdivided according to vegetation characteristics 
brought about by human influences (shifting cultivation) into 34 units. The landscape 
ecological map presents the landscape in its complexity of landforms, soils and vegetation. 
Cross reference of the inventory data reveals a strong relationship between vegetation, altitude 
and soils. This supports the notion that natural vegetation can be seen as a response variable to 
environmental factors such as climate and soil. Since vegetation proves to be correlated with 
altitude, which is assumed to be related to climatic factors, the latter has been taken as the 
highest entry of the map legend. On this basis, the TCP research area is divided into five 
ecological zones (A - E).  
 
The overall orientation of the ecological zones is NNE-SSW and follows the general 
orientation of the geological structures in Southwest Cameroon. The landscape of the TCP 
research area changes considerably from west to east. Altitude rises from approximately 40 to 
over 1000 m asl. Dissected erosional plains, hilly and rolling uplands dominate the western 
part of the area whereas complexes of hills and mountains are found solely in the east. Going 
from west to east the soils change from Ebimimbang to Ebom and Nyangong thereby 
increasing in clay content. Valley bottoms are found throughout the area but are more frequent 
and wider in the west. The natural vegetation changes from low altitude evergreen forest with 
many littoral species to a submontane vegetation with characteristics of cloud forest. Human 
activities have influenced this gradient by logging and shifting cultivation. Along the main 
access roads and in the vicinity of villages mosaics are found of actual fields, thickets on 
recently abandoned fields, young secondary forest and residual patches of tropical moist 
forest. 

 
 
13
1 INTRODUCTION 
 
1.1 FOREST LAND INVENTORY AND LAND EVALUATION PROJECT (LU1) 
 
The Tropenbos Cameroon Programme (TCP) coordinates fourteen interrelated projects in the 
fields of ecology, forestry, economy, social sciences, agronomy and soil science. This report 
presents the results of the reconnaissance scale land inventory carried out in the first phase of the 
research project Lu1, titled `Forest Land Inventory and Land Evaluation' (Lu1). 
 
1.2 RESEARCH OBJECTIVES 
 
Detailed and up-to-date information on the abiotic and biotic environment of the TCP research 
area is a prerequisite for the formulation of a management plan. This information, however, is 
either non-existent (e.g. hydrology and erosion aspects) or not detailed enough for the present 
needs (e.g. climate, landforms, soils, land use, vegetation, and wildlife). The Lu1 project is aimed 
at filling those gaps which is essential for sound land use planning. 
 
The general objective of Lu1 is to provide a scientific framework for sustainable land use 
planning for the TCP research area. This will be realized through the development of a land 
evaluation methodology for tropical moist forests. Moreover, the Lu1 project provides a basis for 
all ecologically oriented research activities within the TCP and permits the extrapolation of the 
results of TCP research to other areas in South Cameroon. 
 
The first phase of the Lu1 project entails an integrated reconnaissance scale (1 : 100 000) survey 
on landforms, soils and vegetation. The present report is the result of this integrated survey, 
delimitating and describing the major landscape ecological units of the TCP area. In the second 
phase of the Lu1 project a qualitative ecological land evaluation will be conducted, investigating 
the suitability of each of the landscape ecological units for a number of relevant land-uses. 
 
1.3 COURSE OF THE STUDY 
 
Preliminary work on the interpretation of aerial photographs, including a five-week mission to 
the study area, was carried out by Mr. Luc Touber of the DLO- Winand Staring Centre for 
Integrated Land, Soil and Water Research (SC-DLO) (Touber 1993a; 1993b).
 
The Directorate General for International Cooperation of The Netherlands' Ministry of Foreign 
Affairs (DGIS) contracted two associate experts for the Lu1 project. Mr. G.W. Hazeu, soil 
scientist, started his work in Cameroon in March 1995. His contract expired in September 1997. 
In March 1995, DGIS appointed Mr. Barend S. van Gemerden as vegetation surveyor whose 
contract expired in December 1997. 
 
The fieldwork for the landform, soil and vegetation survey was carried out between March 1995 
and May 1996. Ms. A. Stoffels carried out the field survey of the northern part in the period 
April-October 1997. 
 
Overall supervision of the Lu1 project was provided by senior soil and vegetation experts of SC-
DLO. Additional assistance was given by a senior GIS expert of the same institute. A total of  
 

 

 
 
15
2 STUDY AREA 
 
2.1 LOCATION AND INFRASTRUCTURE 
 
The TCP research area is situated in Southwest Cameroon at approximately 80 km East of Kribi, 
between 2
°47_-3°14_ N 10°24_-10°51_ E. The area is delimitated by the villages of Bipindi, 
Akom II and Lolodorf (Fig. 1.1). From an administrative point of view the TCP research area is 

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