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

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4.2.5 Valley Bottoms (v) Valley bottoms are poorly to very poorly drained, nearly flat to flat depressions between interfluves. They occupy extensive areas within the uplands and dissected erosional plains. Their widths are mainly 50-150 meters and are thus in general too small to be mapped separately at 1: 100,000 scale. The slope percentages are between 0 and 2%. Stagnation of water is also an important characteristic. Soils are developed in unconsolidated, unspecified, stratified alluvium, which recently has been deposited. The The valley bottoms are found predominantly in the southeast southeast of the TCP research and and in the the western lowlands. Large valley bottoms, i.e. wider than than 250 m, are separately mapped in the present reconnaissance survey. These large valley bottoms cover approximately one percent of the TCP research area. However, this does not reflect the importance of the landform as the majority of valley bottoms are part of the dissected erosional plains, and uplands. 38
5. SOILS 5.1 LITERATURE REVIEW The' Atlas du Cameroun' (1 :2,000,000) and the 'Carte Pedologique du Cameroun Oriental' (1: (1:1,000,000) 1 ,000,000) provide information on the soils in the TCP research area. The scales of these soil maps differ greatly from this reconnaissance inventory (1: 100,000). These maps with their explanatory notes (Segalen, 1957; Martin and Segalen, 1966), together with the' Atlas Regional, Sud-ouest I' by Franqueville (1973) give a good indication of the main soils of Southwest Cameroon. The three main soil types of Southwest Cameroon, according to the above mentioned studies, are are' 'les les sols ferrallitiques jaunes sur roches acides (gneiss)', 'les sols ferrallitiques rouges sur roches acides' and 'les sols alluviaux' (see also section 2.6). According to the' Atlas du Sud Cameroon, scale 1 :500,000 (MINREST and ORSTOM, 1995), the'sols ferralitiques fortement desaturees typiques jaunes ou rajeuni jaunes cl ocres' and 'les sols peu evolues ou bruts' are found around the city of Ebolowa east of the TCP study area. South of the line Ebemvok and Akom 11, a detailed soil study of 65 hectares has been carried out by Roubain who paid special attention to the genesis of soils. He reports that well drained yellowish brown clay soils dominate on gneisses, whereas the reddish brown soils occur on basaltic rocks. Laterite banks are exceptional in this region (ORSTOM - Roubain, pers. comm., 1995). Soil studies in the Mbalmayo area, situated northeast of the TCP research area, were carried out on inventory scale by Yemefack and Moukam (1995) and on detailed scale by Ndjib (1987) and Ngeh et al. (1995). The soils in this area have been developed on (mica)schists, gneisses and granites of Precambrian age. Yemefack and Moukam (1995) classify the dominating well drained yellowish brown clay soils as Xanthic Ferralsols (low cation exchange capacity, low base saturation) with or without textural differentiation. Ndjib (1987) differentiates the strongly weathered soils on the basis of texture, coarse fragment content and colour. He relates these differences to parent material (soils on schists have more coarse fragments than the ones on gneiss) and physiographic positions (development of argic properties on top positions and mid-slopes). Bilong (1992) reports that around Akongo, which is also east of the TCP research area, well drained yellowish brown clay soils are formed on all kinds of parent materials. He relates the yellowish colour to goethite, an iron hydroxide. hydroxide. Goethite, which can be formed under a soil climate climate with with sufficient moisture in the dry seasons, gives a yellowish brown colour to the soil (Bilong, 1992). According to Touber (1993b) the soils in the TCP research are remarkably uniform throughout the area. They are well to moderately well drained, very deep, yellowish brown clay loams to light clays. Variations in depth, internal drainage, texture and gravel content occur. Some patches of redder soils may occur and an altogether different soil type is found in the valleys. 39
Page 2: Landscape ecological survey (1: 100
Page 5 and 6: ABSTRACT Gemerden, van, B.S, G.W. H
Page 7 and 8: 5.2.4 Valley Bottom soils .........
Page 9 and 10: PREFACE ABOUT TROPENBOS The Tropenb
Page 11 and 12: SUMMARY This report presents the re
Page 13 and 14: 1. INTRODUCTION 1.1 FOREST LAND INV
Page 15: 2. STUDY AREA 2.1 LOCATION AND INFR
Page 20: The Ntem complex is comparable to t
Page 24 and 25: as hunting, fishing and gathering o
Page 26 and 27: 3. METHODOLOGY 3.1 LANDSCAPE ECOLOG
Page 29: The described land and soil related
Page 32 and 33: 3.5 LEGEND AND MAP COMPILATION The
Page 35: The moderately dissected uplands wi
Page 39 and 40: Table 5.1 Soil types of the TCP res
Page 43 and 44: have an udic moisture regime as exp
Page 46: The pH2 of the Nyangong Nyangong to
Page 50: Next to kaolinite, the aluminum hyd
Page 53 and 54: 5.5.2 Soil genesis The following so
Page 55: 6. VEGETATION 6.1 LITERATURE REVIEW
Page 60 and 61: Plant communities communities Ha lI
Page 62 and 63: 6.4.2 Podococcus Podococcus - Polya
Page 64 and 65: Most common species in the herb lay
Page 66 and 67: In the shrub like vegetation of of
Page 68 and 69: intensity shifting cultivation take
Page 70: these valley bottoms are sufficient
Page 73 and 74: REFERENCES Aleva, G.J.J. (ed.). (19
Page 75 and 76: Kekem, A.J. van, Pulles, J.H.M. and
Page 78 and 79: 00 o
Page 81 and 82: ANNEX III METHODS FOR CHEMICAL AND
Page 83 and 84: CEC and exchangeable bases (with 1
Page 85 and 86: Conclusions The majority of origina
Page 87:
ANNEX IV Soil profile descriptions
Page 91:
-..0 w PROFILE 71 Legend unit: Soil
Page 95 and 96:
PROFILE 123 Legend unit: Bh2 Soil c
Page 97 and 98:
PROFILE 134 Legend unit: Soil class
Page 99 and 100:
o PROFILE 215 Legend unit: Bh2 Soil
Page 101 and 102:
PROFILE 254 Legend unit: Soil class
Page 104 and 105:
e> 0\ IV.B Ebom soil type PROFILE 1
Page 106 and 107:
o o 00 00 PROFILE PROFILE 140 140 L
Page 108 and 109:
o PROFILE 147 Legend unit: Cui Soil
Page 110:
N PROFILE PROFILE 153 Legend unit:
Page 113 and 114:
VI VI PROFILE PROFILE 181 181 Legen
Page 115 and 116:
PROFILE PROFILE 201 201 Legend Lege
Page 117:
Page 123 and 124:
Page 125 and 126:
PROFILE PROFILE ISO ISO Legend Lege
Page 127 and 128:
Page 129:
w w PROFILE PROFILE 219 219 Legend
Page 133 and 134:
w w Vl Vl PROFILE PROFILE 183 183 L
Page 135 and 136:
Page 137:
ANNEX V Vegetation data ANNEX V Veg
Page 148 and 149:
Vegetation type la U lIb lIe III IV
Page 150 and 151:
Vegetation type la II lIb IIc III I
Page 152 and 153:
2. Non-differential species 2. Non-
Page 154 and 155:
Vegetation type la lIa lib ne Ilia
Page 156 and 157:
Vegetation type la lIa lib lie Ilia
Page 158 and 159:
Vegetation type la lIa lib lie Ilia
Page 160 and 161:
Columbidae Columbidae Treron austra
Page 162:
Sylviidae Sylviidae Bathmocercus ru
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[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

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