Sacred church forests as sources of wild pollinators for the surrounding smallholder agricultural farms in Lake Tana Basin, Ethiopia

Abstract

Remnant natural forests act as a source of wild pollinators that are potentially relevant for crop pollination for sustaining the food production system of smallholder farms. In the Ethiopian highlands, sacred forests scattered within agricultural landscapes harbour wild pollinators. The contribution of wild pollinators to crop pollination services to surrounding smallholder agricultural farms is largely unknown. In this study, we empirically assessed the effects of Ethiopian church forest habitats on crop flower visitation by pollinators on smallholder farms in Lake Tana basin, Ethiopia. Crop flower visitation rates were recorded in 72 crop fields along distance gradients within a 1500 m buffer zone around 15 church forest patches. We constructed cross-validated generalized additive mixed models (GAMMs) to fit the crop flower visitation rates with fixed effect explanatory variables (distance from forest, forest patch size, forest age, forest functional diversity index, forest proximity index and crop type) that are known to potentially influence pollinator visitation in crop fields. Total flower visitation rates decreased with distance to the forest patches across an agricultural landscape. Visitation rates increased with increasing forest patch size, functional richness, proximity index, and age of church forest patches. Overall, we found that the rate of crop flower visitation varies with pollinator-dependent crop types and wild pollinator groups. An in-depth understanding of the forest biodiversity, cultural value, food security nexus enables the promotion of ongoing church forest stewardship in local and regional policies.