444 Richard T. Corlett and Richard B. Primack
recently,honeybees.Conversely,somefunctionally
important groups are found in only one region,
such as leaf-cutter ants in the Neotropics and
cassowaries in New Guinea. Equally significant
are cases where separate evolutionary radiations
have occupied superficially similar niches, such as
the pteropodid fruit bats of the Old World and
the very different phyllostomid bats of the New
World.
Inherent biological differences between rain-
forest regions interact in various ways with
anthropogenic threats to rainforests worldwide.
In some cases, the influence of biogeography on
a key driver of deforestation is direct: Southeast
Asia’s dipterocarp forests are logged indirect pro-
portion to the density of these large trees. In
most cases, however, the effects are less clear. In
our book (Primack and Corlett 2005), we doc-
ument differences in pollination, seed dispersal,
folivory, and predation, but in the absence of cross-
continental comparisons of the community-level
consequences of these differences we can only
speculate about the forests’ differing responses
to human impacts. One likely difference is in
the impact of hunting on key ecological pro-
cesses. Hunters are selective by size and ease of
capture, with kills dominated by different taxa
belonging to different functional groups in dif-
ferent rainforest regions (Robinson and Bennett
2000). For example, hunters favor pigs in Asia
(Robinson and Bennett 2000), frugivorous ungu-
lates in Africa (Faet al. 2005), and large rodents
in the Neotropics (Wright 2003): animals that
interact with fallen fruits and seeds in very dif-
ferent ways, with potentially very different con-
sequences for forest regeneration (Primack and
Corlett 2005). Another potentially important dif-
ference is in the role of frugivorous vertebrates in
forest succession on abandoned land. The early
stages of woody succession in the Neotropics
are dominated by tiny-seeded pioneers dispersed
by fruit bats and emberizid birds (tanagers and
their relatives), which swallow only the small-
est seeds, whereas in the rainforest regions of
Africa and Asia, larger-seeded pioneers are dis-
persed by bulbuls and other birds that swallow
most seeds (Corlett 2002). Bats defecate in flight
while birds defecate from perches, so we would
predict differences in the spatial pattern of pioneer
establishment in each region.
The message for conservation is that there are
many threats and many rainforests. Although
conservationists in one region can learn from
experiences in another, they must acknowledge
not only the obvious differences in political
and social factors, but also the less obvious
biological differences. These differences provide
an additional motivation for saving not just
“the rainforest,” but the many rainforests. In
this chapter we first review the major threats to
rainforests, and then examine how these threats
differ among rainforest regions. Finally, we evalu-
ate various approaches to rainforest conservation.MANY THREATS
Rainforests are threatened throughout the trop-
ics by human activities, but the intensity of each
threat varies by region.LoggingCommercial logging is often the primary driver
of forest degradation and loss (e.g., Curranet al.
2004). Official statistics on tropical timber pro-
duction and trade, though readily available (ITTO
2004; Table 26.1), are an unreliable measure of
logging impacts (Asneret al. 2005). Most tropical
logging harvests at least some trees illegally (illegal
sites, species, or tree sizes) (Barberet al. 2002,
Curranet al. 2004, Ravenalet al. 2004, Richards
2004),andinmanycountries,poorlydocumented
internal markets are much more important than
exports (e.g., Laschefski and Freris 2001).
In most cases only a few species are exported, so
logging intensities are low, but in Southeast Asian
dipterocarp forests many species are grouped into
a few market categories, resulting in more intense
logging (Whitmore 1998). Domestic markets are
usually far less fussy about the species, size, and
quality of logs. This can greatly increase initial
logging intensities in accessible forest areas and
encourages re-logging for smaller, less desirable
trees (Corlett personal observations).