Nutrient flows in smallholder production systems in the humid forest zone of southern Cameroon

Kanmegne, J.; Brussaard, L.; Gansop-Kouomegne, A.

doi:10.1007/s10705-005-8312-3

Cited by 23 publications

(26 citation statements)

References 16 publications

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“…Cultural practices and vegetational composition of these farms have been previously published by Bisseleua and Vidal (2008). The soils were Oxisols and Ultisols, which make up Ϸ80% of the soils in the humid forest region of Cameroon; the pH of the soils ranged from 4.29 to 5.43 (Kotto-Same et al 1997, Kanmegne et al 2006). …”

Section: Methodsmentioning

confidence: 99%

Dispersion Models and Sampling of Cacao Mirid BugSahlbergella singularis(Hemiptera: Miridae) onTheobroma Cacaoin Southern Cameroon

Bisseleua

Yédé

Vidal³

2011

Environ Entomol

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The spatio-temporal distribution of Sahlbergella singularis Haglung, a major pest of cacao trees (Theobroma cacao) (Malvaceae), was studied for 2 yr in traditional cacao forest gardens in the humid forest area of southern Cameroon. The first objective was to analyze the dispersion of this insect on cacao trees. The second objective was to develop sampling plans based on fixed levels of precision for estimating S. singularis populations. The following models were used to analyze the data: Taylor's power law, Iwao's patchiness regression, the Nachman model, and the negative binomial distribution. Our results document that Taylor's power law was a better fit for the data than the Iwao and Nachman models. Taylor's b and Iwao's β were both significantly >1, indicating that S. singularis aggregated on specific trees. This result was further supported by the calculated common k of 1.75444. Iwao's α was significantly <0, indicating that the basic distribution component of S. singularis was the individual insect. Comparison of negative binomial (NBD) and Nachman models indicated that the NBD model was appropriate for studying S. singularis distribution. Optimal sample sizes for fixed precision levels of 0.10, 0.15, and 0.25 were estimated with Taylor's regression coefficients. Required sample sizes increased dramatically with increasing levels of precision. This is the first study on S. singularis dispersion in cacao plantations. Sampling plans, presented here, should be a tool for research on population dynamics and pest management decisions of mirid bugs on cacao.

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Section: Methodsmentioning

confidence: 99%

Dispersion Models and Sampling of Cacao Mirid BugSahlbergella singularis(Hemiptera: Miridae) onTheobroma Cacaoin Southern Cameroon

Bisseleua

Yédé

Vidal³

2011

Environ Entomol

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“…The elevation ranges between 645 and 756 m above sea level. Dominant soils orders in the area are Ferralsols and Acrisols (FAO-ISRIC 1998) with the soil pH varying from 4.29 to 5.43 (Kanmegne et al 2006;Kotto-Same et al 1997). Less-developed and poorly drained soils are found in marshy zones (Ndongo 2008).…”

Section: Study Sitementioning

confidence: 99%

Modeling carbon stock dynamics under fallow and cocoa agroforest systems in the shifting agricultural landscape of Central Cameroon

et al. 2016

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With increasing concerns raised by climate change, understanding biological processes within cocoa (Theobroma cacao L.) agroforest (CAF) and fallow systems is a prerequisite for developing actions related to emission reduction in the shifting agricultural landscape of Cameroon. Carbon (C) stocks and accretion were assessed and modeled in various C components (large trees, small trees, dead wood, litter, roots, soil, and total C) of fallow and CAF systems along a 50-year chronosequence. Several functions were empirically fitted to a time series of C stocks. Large tree, soil, and total C stocks were best described by a logistic growth function while that for small trees by a rational quadratic function. The best-fitted functions explained 72-96 % of C stock accumulation over time. Two metrics describing C stock accretion were derived from these functions: the point of maximum C growth and the C growth coefficient (GC). The rate of maximum growth of total C stock was reached after 12-13 years in both fallow and CAF, with maximum GCs of 6.9 and 6.3 Mg C ha -1 year -1 , respectively. Over the 50-year period, the GCs of total C stocks varied between 0.2 and 6.9 Mg C ha -1 year -1 , with quick accumulation within the first decade that then slowed until it levelled off after 45 years. Over a period of about 30 years, both systems sequestered a total of *200 Mg C ha -1 . This indicates that cocoa agroforests, a main source of income for local populations, can also provide significant climate change mitigation services.

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“…The mean annual rainfall is around 1,900 mm. The soils are Oxisols/Ultisols, which make up about 80% of the soils in the humid forest region of Cameroon and the pH of the soil varies from 4.29 to 5.43 (Kotto-Same et al 1997;Kanmegne et al 2006).…”

Section: Study Sitesmentioning

confidence: 99%

Plant biodiversity and vegetation structure in traditional cocoa forest gardens in southern Cameroon under different management

Hervé

Vidal

2007

Biodivers Conserv

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Floristic surveys were performed in 17 traditional cocoa forest gardens under different management regimes in the humid forest area of southern Cameroon, to assess the impact of intensification on plant biodiversity. This impact was evaluated by analyzing species richness, vegetation structure, carbon sequestration and above ground biomass. We hypothesize that: (a) plant (tree and herbs) species richness is negatively correlated to management intensity and (b) vegetational density predictably change with management intensity. Our results show that management as practiced in traditional cocoa forest gardens in southern Cameroon following a gradient of intensification from extensive cocoa forest gardens with high floristic diversity to intensive ones strongly impacts plant diversity, plant biomass and to some extend carbon storage with possible negative consequences on biodiversity. Great differences in species richness, species composition, and, for trees, diameter at breast height and basal area were evident among the five types of traditional cocoa forest garden systems investigated. In terms of plant species richness, we found a decreasing gradient of plant species numbers from extensive forest gardens to intensive ones. This study also highlights the importance of the Management Index for quantifying differences in the management; this index could be used to standardize certification procedures and assess conservation progress and success. Our findings support the idea that traditional cocoa forest gardens can help to protect many forest species, sustains smallholder production and offer more scope for conservation of biodiversity, at both species-level and landscape-level. Moreover, diverse traditional cocoa forest gardens may help in regulating pests and diseases and allow for efficient adaptation to changing socioeconomic conditions.

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Nutrient flows in smallholder production systems in the humid forest zone of southern Cameroon

Cited by 23 publications

References 16 publications

Dispersion Models and Sampling of Cacao Mirid BugSahlbergella singularis(Hemiptera: Miridae) onTheobroma Cacaoin Southern Cameroon

Dispersion Models and Sampling of Cacao Mirid BugSahlbergella singularis(Hemiptera: Miridae) onTheobroma Cacaoin Southern Cameroon

Modeling carbon stock dynamics under fallow and cocoa agroforest systems in the shifting agricultural landscape of Central Cameroon

Plant biodiversity and vegetation structure in traditional cocoa forest gardens in southern Cameroon under different management

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