So why all the fuss over trees? Trees clean our air and make it more breathable, clean our water, keep soil healthy, buffer floods, and provide habitat for wildlife and enhance biodiversity, all of which contributes to keeping us healthy.
Incorporating trees in and around coffee production, particularly native species, can also provide benefits to coffee and people. Here are just a few reasons why:
- Coffee quality: Evidence shows that coffee under shade produces higher weights of fresh fruits, larger beans and better visual appearance5.
- Climate regulation: As climate change continues, coffee communities are heating up. Given that arabica requires cool temperatures between 18 and 21 degrees Celsius, shifts in on-farm temperatures put production at risk. Trees help reduce temperature volatility, cooling air during the day and keeping it warmer during the night, reducing stress on coffee plants. 6
- Soil health: Fallen leaves and roots help maintain healthy soils by offering natural aeration, nutrients and moisture, providing food for healthy soil fauna that convert the dead plant materials into nutrients available for plant growth. 7
- Erosion prevention: The presence of tree systems helps prevent erosion, particularly on steep slopes and under heavy rainfall, by reducing rainfall impact and holding soil together underground8. Leaf litter from the trees also helps diminish rain-induced erosion9.
- Water capture / regulation: Rainwater is retained on tree leaves, to be released back into the air as evaporation. Leaves on the ground act as sponges, soaking up moisture and gradually releasing it. Shaded soils retain moisture far longer than soils exposed to sun. This is very important as climate-change-induced droughts increase in frequency and intensity. Finally, tree roots usually run deeper than coffee and other crops, so they don’t compete with them for water or soil nutrients10.
- Pest control: Trees provide safe refuge and habitat for pest predators such as birds, bats, ladybugs, spiders, and lizards. These natural predators eat insect pests that might otherwise harm coffee production, and pest outbreaks spread more slowly when trees are mixed into the farm. This natural pest control can decrease pesticide costs11.
- Pollination: Trees provide safe refuges for natural pest predators such as ladybugs, spiders, and lizards, and pollinators such as bees and butterflies, giving them rapid access to the coffee. More tree species support more pollinators, which is important for coffee as the diversity and abundance of bees impacts coffee fruit sets, fruit weights, and yields12.
- Biodiversity: Trees also provide habitat for native birds, reptiles, mammals, and other plant species such as orchids and bromeliads. Each layer of leaves above the coffee has unique microclimatic attributes, providing unique habitats for unique species13.
- Carbon capture: Agroforestry systems in Indonesia can accumulate and store a significant amount of carbon, with values as high as 69.5 tons/ha14. Tree density is one of the most important metrics that influences carbon sequestration, as denser spacing leads to higher carbon stored per area15. Tree age/size is also important, with mature trees holding much more carbon than young trees.
- Income security: Shade trees provide fruits, lumber, and other fibers that can be sold in addition to the coffee, increasing the overall income security of the farmers. Because of their deep roots and energy stores, trees are more resilient to climate change, and are therefore better equipped than coffee to produce fruit in drought years, providing a reliable secondary source of income. Trees can also directly provide fruits, seeds, oils, fuelwood, and construction materials for household use, increasing the economic resilience of the farmers.16
5 Muschler, R. G. (2001). Shade improves coffee quality in a sub-optimal coffee-zone of Costa Rica. Agroforestry systems, 51(2), 131-139.
Vaast, P., Kanten, R. V., Siles, P., Dzib, B., Franck, N., Harmand, J. M., & Génard, M. (2005). Shade: a key factor for coffee sustainability and quality. In ASIC 2004. 20th International Conference on Coffee Science, Bangalore, India, 11-15 October 2004 (pp. 887-896). Association Scientifique Internationale du Café (ASIC).
6 Alemu, M. M. (2015). Effect of tree shade on coffee crop production. Journal of Sustainable Development, 8(9), 66.
Rathmell, L. (2017). Coffee and Conservation: The Ecology and Marketing of Bird Friendly Coffee (Doctoral dissertation).
7 Alemu, M. M. (2015). Effect of tree shade on coffee crop production. Journal of Sustainable Development, 8(9), 66.
8 Iijima, M., Izumi, Y., Yuliadi, E., Sunyoto, Afandi, & Utomo, M. (2003). Erosion control on a steep sloped coffee field in Indonesia with alley cropping, intercropped vegetables, and no-tillage. Plant Production Science, 6(3), 224-229.
9 Li, Xiang, Jianzhi Niu, and Baoyuan Xie. "The effect of leaf litter cover on surface runoff and soil erosion in Northern China." PloS one 9, no. 9 (2014): e107789.
10 Muñoz-Villers, Lyssette Elena, Josie Geris, María Susana Alvarado-Barrientos, Friso Holwerda, and Todd Dawson. "Coffee and shade trees show complementary use of soil water in a traditional agroforestry ecosystem." Hydrology and Earth System Sciences 24, no. 4 (2020): 1649-1668
11 Rice, R. A. (2018). Coffee in the crosshairs of climate change: agroforestry as abatis. Agroecology and Sustainable Food Systems, 42(9), 1058-1076.
12 Klein, A., I. Steffan-Dewenter and T. Tscharntke, 2003b. Fruit set of highland coffee increases with the diversity of pollinating bees. Proceedings of the Royal Society of London270:955-961
13 Greenberg, R., Bichier, P., Angon, A. C., & Reitsma, R. (1997). Bird Populations in Shade and Sun Coffee Plantations in Central Guatemala: Poblaciones de Aves en Plantaciones Cafetaleras en Sombra y Sol en la Región Central de Guatemala. Conservation Biology, 11(2), 448-459.
14 Wiryono et al. 2016. The diversity of plant species, the types of plant uses and the estimate of carbon stock in agroforestry system in Harapan Makmur Village, Bengkulu, Indonesia. Biodiversitas 17: 249-255
15 Roshetko et al. 2007. Smallholder Agroforestry Systems for Carbon Storage. Mitigation and Adaptation Strategies for Global Change. 12: 219-242
16 Davis, H., Rice, R., Rockwood, L., Wood, T., & Marra, P. (2019). The economic potential of fruit trees as shade in blue mountain coffee agroecosystems of the Yallahs River watershed, Jamaica WI. Agroforestry Systems, 93(2), 581-589.