Diverse canopies key to healthy soils: New study from MOCA project

In India, coffee is still grown under native shade tree canopy, which enhances coffee production and quality. However, diverse shade tree canopies are being replaced by fast-growing exotic species, such as the timber tree Grevillea robusta. The implications of the associated trade-offs are not well understood. The WFSC Research Programs project “Managing Trade-Offs in Coffee Agroforests” (MOCA) aims to understand how shade tree diversity management on organic and conventional farms can contribute to more sustainable and resilient coffee production systems.

In a new study in the Journal of Applied Ecology, lead author Dr. Maike Nesper focuses on the effects of different shade tree species on nutrient cycling. The team of researchers studied 25 agroforests that vary in their shade tree diversity, from native multispecies canopy to G. robusta-dominated canopy, and management system (conventional vs. organic).

The results showed that in G. robusta-dominated systems tree litter is more abundant but of lower quality, with less nutrients released at a slower rate to the soil. As a result, the soil has less carbon and available nutrients. These results are highly relevant, as coffee plants across all management systems were deficient in several nutrients. In fact, researchers expect soil fertility to decline in G. robusta-dominated systems, with negative effects on coffee production. The loss of soil fertility would be exacerbated by climate change due to longer dry periods. The researchers, thus, recommend maintaining diverse shade canopies to increase farmers’ incomes and the system’s resilience under global change.

Read the entire article “Simplification of shade tree diversity reduces nutrient cycling resilience in coffee agroforestry” in Journal of Applied Ecology external page here