Indonesia is one of the world’s largest producers and exporters of coffee, with nearly 2 million smallholder coffee farmers managing 1.2 million hectares of coffee land. The country is also one of the most biodiverse areas on the plant, although many of the endemic plant and animal species face extinction due to habitat loss. Coffee is grown primarily in remote villages, and sustainability of the farming system impacts the wellbeing of coffee farmers, rural communities, the economy, and the environment.
Indonesia primarily produces two coffee species—arabica (Coffea arabica) and robusta (Coffea canephora)—which are often grown under different tree species given different elevational and regional distributions. Robusta, which has a higher caffeine content but less desirable flavor profile than Arabica, is concentrated in Southern Sumatra, Lampung, and Bengkulu at elevations ranging from 40 to 900 meters above sea level. These regions produce ~60% of all of Indonesia’s coffee. Arabica coffee grows at higher elevations, ~1,000 to 1,500 meters primarily in North Sumatra, Aceh, and Java.
How are shade trees currently used in Indonesian coffee farms?
Smallholder farmers cultivate coffee in diverse farming systems that can be categorized as complex agroforestry, simple agroforestry, and monoculture. Complex agroforestry, which includes most traditional agroforestry systems, typically include 6 to 30 tree species per farm that form multi-layered strata and provide shade for the coffee. These systems are typically located close to the farmer’s house, require low levels of maintenance, and have irregular spacing of both coffee and shade trees. Additional annual and perennial crops are cultivated together with the coffee, and can be used for household subsistence, for ceremonial or religious purposes, or sold. Despite producing low coffee yields, complex agroforestry systems are considered productive and sustainable at the farm level.
To boost coffee production, simplified agroforestry systems are also implemented by smallholder farmers. These systems typically maintain less than 5 shade tree species per farm that form a single shade stratum. The shade and coffee plantings are more regularly spaced than in complex agroforestry system and benefit from regular maintenance. The shade canopy is primarily dominated by leguminous shade trees (Family Fabaceae) that fix nitrogen, regulate the intensity of sunlight to the coffee, and may provide forage for livestock. Leguminous species also provide biodiversity benefits ecosystem services by attracting and sustaining insect, bird, and mammal communities that may help regulate pests. Trees with fruits that can be consumed or sold are commonly included in these systems as well.
Although simple agroforestry systems are widely promoted by government agencies and NGOs, monoculture systems ("sun coffee") are common in some regions. In North Sumatra, for example, monocultures are promoted and employed to maximize coffee yields, and many farmers may be unaware of shade tree benefits.