Shade-grown coffee helps preserve avian insectivore richness

Study shows that shade trees on coffee farms are able to mitigate effects of warming corresponding to 50 years of climate change

Data resources used via GBIF : 77 species
Ploceus baglafecht
Ploceus baglafecht (Daudin, 1802) observed in Tanzania by Catarina Lobato (CC BY-NC 4.0)

Coffee is a multibillion-dollar industry and an important export product in many developing countries. Rising temperatures threaten production, but growing coffee among larger shade trees may help not only to mitigate the effects of climate change on cultivation, but also to sustain avian insectivore diversity.

In this study, researchers explored potential distributions of insect-eating birds in coffee-growing regions of East Africa. They used the Maxent algorithm on GBIF-mediated occurrences combined with Worldclim temperature layers to model the current and future distributions of 77 species from 20 families.

To explore the effects of shade, they conducted a field study using temperature sensors at 13 coffee-growing sites with varying shade levels. The results were used to adjust the data from the climatic data layers used in the Maxent models.

Their analysis showed that in 50 years, avian diversity might decrease by 25–62 per cent (depending on the climate scenario) on East African coffee farms. If all shade trees were removed immediately, the effect on bird diversity would be similar to 50 years of climate change.

In the most extreme climate scenario in 2075, with no shade trees, bird diversity on farms would be reduced to about 20 per cent of the current level.

Schooler SL, Johnson MD, Njoroge P and Bean WT (2020) Shade trees preserve avian insectivore biodiversity on coffee farms in a warming climate. Ecology and Evolution. Wiley 10(23): 12960–12972. Available at: https://doi.org/10.1002/ece3.6879