Tree species selection for silvopastoral systems from an ethnoecological approach: I. The new ethnoecological selection index (EESI) and key interactions in the pastoral agroecosystem

We aimed to integrate local and scientific knowledge to select tree species for elaborate silvopastoral systems with the proposition of a multi-criteria decision-making support tool. We conducted a pilot study in the south of Espírito Santo, a tropical Brazilian region. The survey of trees took place on 136.9 ha of pastureland at nine rural properties. We interviewed 42 family farmers that practiced cattle ranching and had trees in their pastures. A multi-attribute utility function was created to select and order ten tree species with cultural and ecological potential for pasture afforestation. We evaluated these species regarding their interactions with soil cover, herbaceous biomass and bovine grazing. The ten selected tree species showed orderly decreased EESI (Ethnoecological Selection Index) values ranging from 0.8327 to 0.5958. All ten species were native, 30% were nitrogen fixers, 70% had Use Value, and none were invasive. Regarding soil cover, herbaceous biomass, and grazing, the under the crown and outside the crown strata showed no statistical differences between them. The crown base height and herbaceous ground cover positively correlated, while the canopy cover and herbaceous ground cover negatively correlated. The EESI creates an interface between the traditional knowledge of family farmers and scientific knowledge.