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

Although agriculture is a major factor in environmental change, the level of its impact is likely to vary with farming practices. Thus, we sought to determine how farming practices might affect the natural compartment of agroecosystems and the sustainable use of land. In particular, we examined ant biodiversity and community composition as related to orchard design and management practices in the mango- and citrus-based orchard agroecosystems of Senegal. Ants were collected using pitfall traps in 49 orchards classed in four types based on their design and management. The results showed that the effect of practices was significant, albeit weak, and a typology of orchards based on design and management practices was congruent with a typology based on the composition of ant communities. The different types of orchard were seen to differ in the richness and diversity ant species. Moreover, ant richness and diversity was positively correlated with tree richness. We were also able to identify some ant species as being related to agricultural practices. For instance, Monomorium salomonis (L.) was closely associated with high irrigation, fertilization and pesticide use, whereas Paltotyreus tarsatus was associated with greater tree richness, high local ground coverage by the tree canopy, more leaf litter and great variation in the local tree planting density. This study appears to be the first attempt to characterise the relations existing between orchard design and management practices and the functioning of Sahelian fruit-based agroecosystems thereby furthering the goal of providing recommendations for sustainable management strategies.