ROLE OF CACAO IN THE CONSERVATION OF
BIODIVERSITY
The development of shade-grown agriculture systems presents
both opportunities and challenges for biodiversity
protection. Agro-ecosystems generally harbour more
biodiversity than crops grown in monocultures and can
retain a significant component of the biodiversity that
occurs in adjacent, ecologically similar reserves. However,
cacao farms without necessary habitat elements can be
depauperate of vertebrate biodiversity, particularly arboreal
mammals such as sloths and primates (Rolim & Chiarello
2004). Moreover, the continued clearing of original
forests for agriculture, even when grown underneath an
overstorey of native trees, continues to erode tropical biodiversity.
In such cases, remnant animal communities are
typically biased toward generalist species at the expense of
species with specialized habitat or foraging requirements
(Harvey, Gonzalez & Somarriba 2006). Nevertheless, our
results indicate that some species with specialized habitat
requirements, not to mention limited dispersal abilities,
such as C. hoffmanni, can be self-sustaining within an agroecosystem
of modest size (c. 4 km2) given that required
habitat elements are retained. Similarly, maned sloths in
the Brazilian Atlantic forest have been found to use biologically
rich cacao farms for foraging and can produce offspring
in this habitat, although they may require adjacent
tracts of intact forests to persist (Cassano, Kierulff & Chiarello
2011). In contrast to C. hoffmanni, our results indicated
that B. variegatus did not appear to be self-sustaining
in the absence of immigration, perhaps due to its more
specialized dietary needs and sedentary behaviour. The
differences in demography between these two ecologically
similar species emphasizes that even subtle variation in lifehistory
strategies can interact with environmental conditions
present in an agro-ecosystem and lead to different
levels of vulnerabilities among species. Clearly, features
within agricultural systems required to maintain sensitive
tropical species will vary according to the life-history strategy
of the species in question. More broadly, the value of
human-modified landscapes for biodiversity may be overestimated
when some species are dependent on immigration
from intact habitats.