- Allow epiphytes and parasitic plants to grow on the canopy trees
•Retain dead limbs and snags in the plantation to provide additional
resources for birds - Allow the tree canopy to attain at least 12 m in height
•Ensure that coffee fields are bordered with a living fence or border strip of
trees and shrubs or natural second-growth vegetation (Smithsonian Migra-
tory Bird Center 1999).
In commercial polyculture and specialized shade systems where the shade
canopy is planted by the farmers, a variety of nondeciduous Ingaspecies
(rather than Erythrinaand Gliricidia,which are deciduous part of the year)
have been suggested as the dominant shade species to ensure that flowers and
fruits are available for longer periods of time and that the coffee plantation has
shade in the dry season when canopy cover for both migrant and resident birds
is most critical (Smithsonian Migratory Bird Center 1999). There are hopes
that the higher price of these certified products will entice farmers to conserve
shaded coffee plantations and the species in them.
Biodiversity in coffee plantations can be further increased; for instance,
species richness in the ground cover plant layer can be promoted by creating
a mosaic of shade conditions and applying selective management. Native
species suitable for shading coffee and producing useful products could be
identified, propagated, and introduced into coffee plantations (Linkimer
2001; Yépez 2001). Useful diversity can also be increased by exchanging man-
agement information and perhaps germplasm between coffee-growing areas.
For instance, very few timber species are used in Central American coffee
plantations despite the high potential to use many other native species. It is
worth noting that earlier attempts to diversify coffee production systems have
failed because no market or processing facilities were concurrently developed
with the planting of useful species in the coffee plantations (Godoy and Ben-
nett 1989). Special efforts should be made to diversify big farms because many
small coffee farms already maintain high levels of useful diversity.
Conclusions
The concern about the environmental impacts of agriculture, the global loss
of forests and biodiversity, the valorization of environmental services (e.g.,
water, soil conservation, carbon sequestration to mitigate global warming, and
aesthetic and recreational aspects), and the fall of international coffee prices
caused by overproduction have changed the value of coffee plantations grown
under diverse shade canopies. In shaded coffee plantations production costs
can be reduced, coffee grain and cup quality can be increased (Guyot et al.
1996), plantation longevity can be increased, and new markets with preferen-
tial prices can be accessed (i.e., organic markets, markets for environmentally
218 III. The Biodiversity of Agroforestry Systems