Agroforestry: Focus on Coffee
Coffee and Cacao are each widely cultivated in the
tropics and each is fundamentally an understory plant
(plates 17- 8– 9). Coffee is a shrub, the Cacao is a small
tree. Agroforestry is the practice of crop cultivation
within a forest. Only the planting of the understory
crop alters the forest. The canopy and other attributes
of the forest remain more or less unaltered (but see
below).
Agroforests are floristically less complex than other
forests, often with a dominant canopy species, such as
the widespread tree Inga. Structural complexity varies
considerably, depending upon how much the forests
are manipulated. There is, for example, a gradient of
shade coffee agroforests, ranging from rustic, where
there has been essentially no canopy alteration, to
various degrees of plantation forests, where select
species such as Inga are planted to varying densities.
Coffee is in the Rubiaceae, a large plant family of
some 550 genera and 9,000 species. Two species,
Coffea arabica and C. canephora (also known as C.
robusta) are cultivated. Caffeine averages from 0.8
to 1.4% in C. arabica and 1.7 to 4.0% in canephora.
Many varieties, called cultivars, have been developed
within each species. C. arabica is endemic to Ethiopia,
southeastern Sudan, and northern Kenya, but today
it is planted over 10 million ha (25 million ac) within
more than 50 countries, representing about 70% of the
world’s coffee crop.
In the Neotropics, about 95% of the coffee grown is
C. arabica. In 2006, the countries producing the most
coffee were Brazil, Vietnam, and Colombia. While
coffee is genetically adapted to grow in shade, cultivars
have been produced that thrive in full sunlight. This has
resulted in the progressive replacement of traditionally
shade- grown coffee with high- intensity agriculturally
grown coffee, a trend that has caused concern among
those interesting in conserving tropical biodiversity
through more traditional agroforestry.
Traditional coffee production, in what are called
rustic coffee plantations, involves replacement of
understory species with coffee plants. Forests remain
relatively unchanged, aside from the dominance of
coffee plants throughout the understory (plate 17- 10).
But coffee plants grow more rapidly with more sun,
so in many cases some canopy trees are taken out to
open the forest and permit much more light, reducing
the biodiversity value of the rustic coffee plantation(plate 17- 11). Sometimes the coffee is combined with
other crop plants, such as various fruits, vegetables,
and medicinal plants to form a complex polyculture.
A more focused approach, usually called commercial
polyculture, requires additional manipulation and
simplification of the ecosystem to permit greater
sunlight and faster growth of coffee. This approach
may be extended to create reduced or specialized shade
by replacing canopy tree species with select species of
Inga, Erythrina, Gliricidia, or other genera. Inga is a
canopy- level species, but the others are small trees that
allow far more sunlight to penetrate. Finally, there is the
full- sun coffee plantation, a monoculture that appears
identical to those of traditional large- scale agriculture.
Sun- coffee plantations have been simplified to thePlate 17- 9. Cacao fruits grow from cauliflorous flowers
(chapter 3) on understory trees. Photo by John Kricher.Plate 17- 8. Coffee beans ripening on the plant. Photo by John
Kricher.chapter 17 human ecology in the tropics 371