Shade-grown coffee is a form of crop produced from coffee plants grown under a canopy of trees.A canopy of assorted types of shade trees is created to cultivate shade-grown coffee. This method allows shade-grown coffee systems to mimic natural forest conditions, and also promotes ecological interactions. Increased canopy cover in coffee systems has been shown to enhance biodiversity and support conservation efforts. Shade-grown coffee systems can improve soil stability, reduce erosion, and enhance water retention, compared to full-sun systems. Further, shade-grown systems can also contribute to climate change mitigation, as it supports carbon storage and reduces deforestation. Because it incorporates principles of natural ecology to promote natural ecological relationships, shade-grown coffee can be considered an offshoot of agricultural permaculture or agroforestry. The resulting coffee can be marketed as "shade-grown".
History Coffee (especially Coffea arabica) is a small tree or shrub that grows in forests in its wild form, and was traditionally grown for commercial purposes under other trees that provided shade. Since the mid-1970s, new sun-tolerant trees and shrubs have been developed in response to fungal disease presence, especially coffee leaf rust (Hemileia vastatrix), and with an aim to yield higher production rates. As a result of modernization and a push for higher yielding crops, sun-tolerant coffee plants were created to produce larger yields through higher-density, open planting, but cultivation practices used for them may be unsustainable and often have a negative impact on the environment. This has resulted in a new trend in support of shade-grown coffee. Although shade-grown coffee is a production system widely regarded as environmentally sustainable, enabling biodiversity conservation, enhancing pest-control services from birds, and contributing to climate change adaptation, there is an important potential tradeoff, namely lower coffee yields. Yet few studies have explicitly examined this tradeoff and the economic incentives required for smallholders to adopt shade practices. A 2014 study has shown that the proportion of land used to cultivate shade-grown coffee, relative to the total land area used for coffee cultivation, has fallen by nearly 20% since 1996.
Ecological impacts
Species diversity Recent studies have shown that there is a direct correlation between the structural complexity of a coffee plantation and the number of species that can be found there. The forest-like structure of shade coffee farms provides habitat for a great number of migratory and resident birds, reptiles, ants, butterflies, bats, plants and other organisms.Of all agricultural land uses, shade-grown coffee is most likely the crop that supports the highest diversity of migratory birds, native flora and fauna. In all of the studies, a clear spectrum of species richness emerged ranging from high species diversity in "rustic" shaded polycultures to extremely low species diversity in unshaded monocultures. Shade-grown systems provide important habitat for birds and other wildlife due to their forest like environments.
Plants Biological diversity in traditional "rustic" plantations can be extremely high, ranging from 90 to 120 species of plants on a single site. Tree species richness in shade-grown coffee sites ranges from 13 to 58 species per site. Herb diversity was found to be 2 to 4 times that of tree diversity on any given site, and shrub diversity was fairly low in all sites. Epiphytes are also extremely diverse in shaded polycultures; 90 total epiphytic species were found in 10 sites of shade-grown coffee plots.
Insects Insect communities can be fairly complex in shaded coffee plantations. 609 species of insects from 258 families were found in a sample from ground level to 2 meters in a shaded polyculture coffee plantation near Tapachula, Chiapas. 37% of the individuals were herbivores that could be a potential crop pest if not kept in check by the predators and parasites, which represented 42% of the total species.
Birds Shade-grown coffee provides important habitat for both native and migratory bird species. The most prominent migratory species, which breed in North America and overwinter in the tropics, include warblers, flycatchers, vireos, and redstarts. 184 bird species, 46 being migratory, were recorded in traditional coffee plantations near Soconusco, Chiapas, while as few as 6 to 12 species were recorded in an unshaded monoculture. In a study of shade vs. sun coffee comparisons in Guatemala, overall bird abundance and diversity were 30% and 15% greater, respectively, in shaded farms than sun farms. Shade-grown trees house two-thirds of the bird species found in natural forests in the same geographic areas. Much greater densities of migratory birds were found in shade-grown coffee sites than in local natural habitats. This is most likely due to the greater abundances of bird-dispersed fruit trees, flowering plants, and insects found in the shade sites. Bird communities in traditional polycultures are composed mainly of canopy and midstory species feeding on fruit, insects, and nectar.
Mammals A study in the Western Ghats of India showed that 28 species of mammals occurred in shade-coffee plantations. This study also showed that distance from protected wildlife reserves had a negative influence on mammal species richness.
Biotic processes
Pest control The high species diversity found in shaded polycultures allows for relatively complex food webs to form. Birds and mammals alike play a large role in pest control by eating many herbivorous insects. In a study in Jamaica, birds were excluded from one coffee plantation and resulted in a 70% increase in the proportion of coffee fruits infected by the coffee berry borer, an insect pest species. Biological control by birds acting as predators on the coffee berry borer in Jamaica was calculated to be worth $75/hectare in 2005, averaging $1004/farm studied. This equals about 30% of the per capita gross national income for that time. Another study in Puerto Rico used exclosure plots to exclude lizards, found to be more abundant in shade-grown coffee than sun-grown coffee, showed that the exclusion of lizards led to an increase in leafminers, an insect that is a serious pest to coffee plants.
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