Factors Affecting Biodiversity in Coffee
Plantations
The ability of coffee plantations to harbor wildlife depends on a variety of fac-
tors, including the diversity and density of trees, the presence of wild plants in
the understory, plantation management (especially the use of agrochemicals),
and the composition and structure of the surrounding landscape.
The floristic and structural complexity of shaded coffee plantations is of
utmost importance in ensuring the sustainability of biodiversity, given that
positive relationships have been found between vegetational complexity and
insect diversity, mammal diversity, and birds (Perfecto and Snelling 1995;
Greenberg et al. 1997; Wunderle and Latta 1998). Consequently, coffee plan-
tations that have a structurally and floristically diverse tall tree layer generally
host a higher animal abundance and species richness than plantations of low
stature and low diversity. For example, studies in Mexico found up to 184 bird
species in shaded coffee plantations (Moguel and Toledo 1999), compared
with only 6–12 bird species in nonshaded plantations (Martinez and Peters
1996). More than 30 species of terrestrial ants have been encountered in the
traditional, shaded coffee agroecosystem of the Central Valley in Costa Rica,
whereas only 6 species were found in the modern, unshaded systems (Perfecto
and Vandemeer 1996). This pattern of higher diversity in diverse, shade-
grown coffee plantations than in sun-grown coffee is consistent among bird,
insect, and mammal populations (Perfecto et al. 1996; Moguel and Toledo
1999).
Differences in the fauna present in different types of coffee plantations
may also reflect differences in food availability in individual coffee plantations.
For example, coffee plantations shaded with Ingatrees are likely to have high
numbers of nectarivorous and omnivorous bird species because Ingaflowers
are important sources of nectar (Greenberg et al. 1997; Wunderle and Latta
2000); in addition, the wide variety of insects found on Ingaleaves (including
grasshoppers, katydids, lepidopteran larvae, beetles, and spiders) makes them
key foraging sites for insectivorous species (Koptur 1983; Wunderle and Latta
2000). In contrast, rustic coffee plantations that contain high densities of
fruit-producing trees are likely to support high numbers of frugivorous bird
species (Greenberg et al. 1997). The number of butterflies in coffee planta-
tions is similarly influenced by the abundance and diversity of wild plant
species that provide nectar and larval food sources.
The presence of fauna in coffee plantations may also be related to manage-
ment aspects such as the thinning or pollarding of shade trees and the use of
pesticides. It is to be expected that coffee plantations that are more intensively
managed or use greater quantities of pesticides would have lower populations
and lower species richness (Perfecto and Vandermeer 1994; Perfecto et al.
1997). However, no exact data are available about these relationships,
216 III. The Biodiversity of Agroforestry Systems