Potential of natural and improved fallow using indigenous trees to facilitate cacao replanting in Ghana

Abstract

Poor establishment, due to loss of soil fertility, weeds and lack of appropriate shade, is a major constraint to replanting cacao on previously used land. Spathodea campanulata, Newbouldia laevis and Ricinodendron heudelotii planted as monospecific improved fallow and Terminalia ivorensis, T. superba and Antiaris toxicaria planted as a multispecies improved fallow and a natural tree fallow were assessed for their potential to facilitate cacao replanting in a randomized complete block design experiment. Simpson and Shannon diversity indices and species richness in the natural tree fallow were 0.6, 1.6 and 20, respectively, at 4 years after trial inception. The Multispecies and the R. heudelotii improved fallows had better height growth, crown development and light transmission characteristics, which are desirable for cacao shade. However, these were not comparable to S. campanulata or the natural tree fallow in terms of improving microsite topsoil pH, % organic carbon and % total nitrogen and site capture. Since optimum fallow period is shortened by growing fast-growing trees, the height growth rate [2.0 m per annum in all the treatments except N. laevis indicates the suitability of these species for improved fallow. The trees species showed different and complementary characteristics and from a standpoint of biodiversity conservation and the future floristic composition of the landscape the natural tree fallow with its diversity of tree species may be recommended as a rehabilitation technique to facilitate the replanting of cacao with a diverse overhead shade.

Leaf Litter Decomposition and Mitigation of CO2Emissions in Cocoa Ecosystems

“…The leaf litter of the shade species had a much higher (P < 0.05) decay rate constant than the cocoa leaf litter treatment. Anim-Kwapong and Osei-Bonsu [75] found a similar high k d value of 2.51 × 10 −3 /day (recalculated from authors' half-life value of 9.22 for N. laevis) for N. laevis also collected from the same ER of Ghana. In respect of the decomposition rate of cocoa leaf litter in the present study, comparable leaf litter decay rates have been reported by Owusu-Sekyere et al [76] and for some forest tree species [77].…”

Tree diversity and its ecological importance value in organic and conventional cocoa agroforests in Ghana

“…Additionally, pioneer species are better able to regenerate and survive in disturbed forests or forest-like systems, such as cocoa agroforests, than other species thus contributing to their abundance on cocoa farms. Indeed, most of the species among the ten most abundant species such as Milicia excelsa , Antiaris toxicaria , Alstonia boonei , Entandrophragma angolense , Ficus exasperata , Newbouldia laevis , Terminalia ivorensis , Terminalia superba and Spathodea campanulata have been cited as being compatible with cocoa by both farmers and scientists in Ghana [22; 40; 41]. That notwithstanding, the vegetation in the study area has been cited to be predominantly pioneer species due to significant deforestation that has taken place over the past five decades [23; 27].…”

Farmers in Côte d’Ivoire value integrating tree diversity in cocoa for the provision of ecosystem services

“…They were valued by farmers for the quality of shade, soil fertility improvement and in the case of S. campanulata and R. heudelotii for their positive role in increasing soil moisture availability, especially in the dry season. The role of S. campanulata in increasing soil moisture has been previously recorded in Ghana (Anim-Kwapong and Osei-Bonsu 2009). Ricinodendron heudelotii is also known to root deeply, likely to reduce competition for water with cocoa, and because of the high market potential of its kernels, has been indentified as a promising tree species for domestication in West Africa (Tchoundjeu and Atangana 2007).…”