Northwestern Thailand has a higher proportion of natural
forest landscapes (Fig. 1D) and protected nature reserves (e.g.,
Gray et al. 1991; see http://www.trekthailand/net/list/ for
latest data) than the rest of Thailand. However, we did not
find a relation between habitat disturbance (in three classes)
and local diversity for the eight sites with habitat descriptions
available (data not shown). In Borneo, local sphingid diversity
is not significantly influenced by human habitat disturbance
(i.e., agricultural landscapes do not have a lower sphingid
diversity than primary forests, Beck et al., 2006b), but species
composition is. Thus, large, forested habitats might allow the
persistence of forest specialists that are not found elsewhere,
and hence increase regional species richness (we do not have
detailed enough data to test this at continental sites). However,
species richness decreases in Malaysia although large forests
can be found there.