Mango-based orchards in Senegal: diversity of design and management patterns

Abstract

-Introduction. Mango-based orchards in Senegal occur in a large diversity of cropping systems, but few typologies of these systems exist and none are associated with their comprehensive and quantitative analysis. In this study we defined and characterized the typology of these systems based on a quantitative assessment of their planting design, management, vegetative state, hedgerow structure and infestation by a major pest of mango, the Bactrocera invadens fly. Materials and methods. Multivariate analysis and clustering methods were applied to data from 64 mango-based orchards and their surrounding hedgerows sampled in the Dakar and Thiès regions, in Senegal. Results and discussion. Four types of cropping systems were identified according to orchard design and management patterns: (1) 'No-input mango diversified orchards', (2) 'Low-input mango orchards', (3) 'Medium-input citrus-predominant orchards' and (4) 'Medium-input large mango-or citrus-predominant orchards'. Orchard characteristics varied among these patterns. For instance, vegetation was dense and homogeneous in system 1, and the mortality rate of trees was high in system 2 but low in system 3. Orchards of systems 3 and 4 were mostly associated with hedgerows with, respectively, boundary-marking and defensive species. Lastly, the number of B. invadens flies was high in orchards of system 4, whereas it was low in those of system 2. Conclusion. The diversity of mango-based cropping systems in Senegal is now well described and quantified. This characterization is a preliminary step that is essential for further studies aiming to improve these systems.Senegal / Mangifera indica / fruit trees / orchards / typology / design / crop management / Bactrocera invadens / hedges / multivariate analysis Vergers à base de manguiers au Sénégal : diversité des modèles de conception et de gestion.

Relations between the design and management of Senegalese orchards and ant diversity and community composition

“…The previous study by Grechi et al (2013) in the same agroecosystems showed a close relation between the locality and the orchard type. A causal link between the climatic parameters of localities and orchard type is unlikely because the design and management of orchards in the same study zone were mainly based on historical, sociological and economic choices rather than on environmental grounds (Vannière et al, 2004).…”

“…Type (4) orchards, which displayed higher intensification levels with a less diversified set of trees (Grechi et al, 2013), had the lowest ant diversity and richness. On the other hand, type (3) orchards, with the greatest tree richness, planting densities and variation in local planting density (Grechi et al, 2013), had the greatest ant diversity and richness. These results confirm previous studies showing the frequent increase in ant diversity and richness observed in heterogeneous landscapes Fig.…”

“…The asterisk indicates the variables used in the ant diversity and richness and RDA analyses. For details on the variables, see Grechi et al (2013). …”

“…In a previous study carried out on 64 orchards sampled within the Niayes and Plateau de Thièsregions, an orchard typology was built based on 26 variables describing orchard design and management practices (Grechi et al, 2013). Orchard typology was obtained by a Hierarchical Multiple Factor Analysis (HMFA) performed on the variables of the 'orchard design' and 'orchard management' groups (Table 1).…”

“…Examples include studies of the impact of human management practices on ecological processes in cropping systems (Weibull and Östman, 2003). In Senegal, it is known that orchard agroecosystems are very diverse in their varietal composition, their planting design and their management practices (Vannière et al, 2004;Grechi et al, 2013), but no prior study has examined the relations existing between orchard design and management practices and underlying ecological processes.…”