Shade-grown coffee
Since the mid-1970s,[1] 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.
[6] 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.
[8] Biological diversity in traditional "rustic" plantations can be extremely high, ranging from 90 to 120 species of plants on a single site.
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.
The most prominent migratory species, which breed in North America and overwinter in the tropics, include warblers, flycatchers, vireos, and redstarts.
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.
[11] The high species diversity found in shaded polycultures allows for relatively complex food webs to form.
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.
[7] The presence of canopy and midstory vegetation in shaded polycultures helps reduce soil erosion as well stabilize steep, mountainous slopes.
The added leaf litter and other plant material from these shade trees also contribute to increased soil nutrients such as carbon and nitrogen.
Sun-grown coffee requires numerous chemical fertilizers, insecticides, herbicides, fungicides, and pesticides to be added to promote growth.
For this reason, shade-grown coffee is beneficial to producers who can not afford the cost of fertilization required for intense cropping systems under full sun.
[12] Rigorous evaluation and management of the companion trees is required in order to realize the advantages of shade-grown coffee.
[14] There is a complex interaction between shade, meteorological effects such as rainfall or dry periods, and aerial dispersal of coffee leaf rust.
Coffee shrubs are planted more densely, and the farm looks very organized and deliberate with a focus on generating products that are solely market-based.
[18] In south-east Asia, suitable trees include Erythrina subumbrans (tton tong or dadap), Gliricidia sepium (khae falang), Cassia siamea (khi lek), Melia azedarach (khao dao sang, Indian lilac), and Paulownia tomentosa, a useful timber tree.
Coffee bushes are exposed to direct sunlight and require high inputs of chemical fertilizers and pesticides as well as an intensive yearly workforce.
