CARBON CONTENT IN CACAO AFS

(1)

=

CARBON CONTENT IN

CACAO

AFS

• Afforestation of savannah has a positive effect on the

total above ground carbon with an annual accumula-tion of 5.7% resulting in similar carbon stocks as cacao

plantations after forest in ± 60 years.

• Setting up a cacao plantation after forest decreases the

mean above ground carbon stock but no significant

change was shown with aging of the cacao plantations.

• For the two classes of soil texture found in the cocoa

plantations setup after savannah, soil organic carbon

increases with the plantation age.

Field studies were conducted in Bokito in the central region of Cameroon. Plantations with an age gradient of 0 to 80 years were selected to assess aboveground carbon accumulation in cacao and associated trees as well as the soil carbon content. The two previous land-use types: savannah and gallery-forest were also included in the analysis for comparison.

Introduction

y = 0.87x + 15.04 R² = 0.42** 0 20 40 60 80 100 120 140 160 180 0 10 20 30 40 50 60 70 80 90

Above ground carbon (Mg/ha)

Annual accumulation 5.7% A R² = 0.61** 0 0.5 1 1.5 2 2.5 3 3.5 5 10 15 20 25 30 35 40 Clay content (%) C R² = 0.39* 0 0.5 1 1.5 2 2.5 3 3.5 0 10 20 30 40 50 60 70 80 90

Soil carbon content 0-15 cm (%)

Plantation age (years)

B

Annual accumulation 9.7‰

Annual accumulation 6.0‰

Carbon dynamics in

cacao agroforestry plantations

setup after forest or

savannah:

A chronosequence analysis in a forest - savannah transition zone in Cameroon

Previous studies in the forest-savannah transition

zone of Bokito in Central Cameroon have shown that

smallholder farmers were able to realize afforestation by

creating cacao plantations on savannah land (Fig: 1)

1,2

.

Compared to plantations setup after forest in the same

region, cocoa production levels and associated tree

species densities were found to be comparable on the

long-term

1

. In the light of climate change, afforestation

of savannah with cacao plantations could be of great

potential due to its significant storage of carbon.

Nijmeijer, A.

1,2

Harmand, J.M.

,3,4

Bouambi, E.

2

Lauri, P. E.

4

Saj, S.

1

1. _{CIRAD, UMR System, Montpellier, France}2. _{IRAD, Nkolbisson, Yaoundé, Cameroon}3. _{CIRAD, UMR Eco&Sols, Montpellier, France}4._{ICRAF, Yaoundé, Cameroon}5. _{INRA, UMR System, Montpellier, France}

Methods

Results

Total aboveground carbon (AGC) was found to be highest

in the gallery-forest control plots (118 Mg ha-1) and lowest in the savannah control plots (trees and herbs: 8 Mg ha-1; Fig: 2).

Conclusion

Cacao plantations after forest Forest control

Cacao plantations after savannah Savannah control

Correlations cacao plantations after savannah*

Legend

Clay content 20 - 24% Clay content 10 -15%

*No correlations were found in cacao plantations after forest.

Fig. 2: Mean total above ground carbon stocks in forest- and savannah

control plots, cacao plantations after forest and after savannah.

Fig 3: Changes in (A) above ground carbon stocks and (B) soil carbon

content with the plantation age. (C) Correlation between soil carbon content

and soil clay content.

1. Jagoret, P., Michel-Dounias, I., Snoeck, D., Ngnogué, H. T. & Malézieux, E. Afforestation of savannah with cocoa agroforestry systems: a small-farmer innovation in central Cameroon. Agrofor. Syst. 86, 493–504 (2012).

2. Saj, S., Jagoret, P. & Todem Ngogue, H. Carbon storage and density dynamics of associated trees in three contrasting Theobroma cacao agro-forests of Central Cameroon. Agrofor. Syst. 87, 1309–1320 (2013).

Compared to their previous land uses, mean total AGC was around 40% lower in cacao plantations set-up after forest while AGC stocks of plantations set up after savannah have increased by 630%.

AGC of cocoa plantations after forest stayed relatively stable over time while it increased significantly (p < 0.01) with the age of the plantations setup after savannah

(Fig: 3A). According to the soil

texture, different tendencies of soil C accumulation over time were found in cocoa plantations setup after savannah, while no change in soil C content was observed after forest over time (Fig: 3B, C).

References 0 a ab b c 20 40 60 80 100 120 140 Forest

control Plantationsafter forest Plantationsafter savannah

Cacao trees

All woody species including cacao

Savannah control

Above-ground carbon (Mg/ha)

Fig. 1: What influence has converting savannah or forest to complex cacao agroforestry systems on the long-term carbon budgets? Complex Agroforestry system Precedent Forest Land-use change Land-use change Precedent Savannah Associated trees