Food enrichment as driver for ecosystem service provisioning in shade-grown coffee

Background/Question/Methods

As the demand for the reliable provision of virtually all ecosystem services increases, it is imperative to conduct experimental research that improves our understanding of how services interrelate and the mechanisms or drivers affecting them. Furthermore, humanity urgently needs ecological research to identify management actions that can increase multiple ecosystem services synergistically. We experimentally tested a potential shared driver of several ecosystem services involving birds: avian diversity and abundance, seed dispersal by birds, and arthropod removal by birds. We used similarly managed shade grown coffee farms as replicates, enhancing three of six farms with fruit resources for 18 months. Exclosures were set up over coffee plants in farms to measure arthropod removal by birds, and mist-nets were used to estimate bird richness and abundance in farms in response to the supplemental fruit resources.

Results/Conclusions

Farms with the experimental fruit resource enrichment (the driver) had significantly greater bird species density (50%), overall abundance (55%), and abundance of understory insectivore specialists (89%). Seed disperser abundance was not significantly different between treatment and control farms. Furthermore, pest control by birds was not affected by the driver, showing constant levels of arthropod reduction occurring in farms with and without the food resource enrichment. The results of this study highlight the difficulties associated with managing for various ecosystem services simultaneously based solely on an observed spatial concordance among the selected services without an understanding of the mechanism behind or the cause of the relationship.