fire most commonly occur in managed pastures or slash-and-burn fields.
Agroforestry areas normally are less susceptible to fire than pastures and fields
because the closed or semiclosed tree canopy creates a dark, humid environ-
ment with low fuel loads and, especially, because agroforesters tend to protect
their investment in tree planting (e.g., through firebreaks). Therefore, agro-
forestry areas could act as potential fire buffers to remnant habitats and are
more likely to inhibit rather than promote the spread of fire.
Population Sinks
Corridors could act as population sinks by attracting individuals to areas
where they experience reduced survival or reproduction. By aiming to pro-
mote wildlife movement across the landscape, corridors may funnel wildlife
through private lands, increasing their exposure to hunters, poachers, preda-
tors, and domestic animals (see Chapter 13, this volume). Moreover, corri-
dors may maneuver organisms into an environment with limited resources
and potentially superior competitors such as generalist and edge species,
which could reduce their reproductive success (e.g., nest predation; Angel-
stam 1986) and compromise their survival (Simberloff and Cox 1987). To
date most research into increased mortality in corridors has been extrapolated
from edge effect studies in fragmented habitats (Gates and Gysel 1978), and
little evidence is available on mortality rates in corridors compared with other
habitats.
Financial Costs and Benefits of Corridors
There has been some suggestion that the financial cost of corridors may out-
weigh their benefits and that scarce conservation dollars could be better spent
on other initiatives (Simberloff et al. 1992). For example, in areas such as east-
ern Madagascar, where less than 5 percent of original rainforest remains
(Smith 1997), conservation options might include purchasing land for pro-
tecting remnant natural habitat, creating corridors between remnant reserves
(which may not function for all species), and revegetating lands that adjoin
reserves to provide additional habitat area. Given that resources for conserva-
tion are highly limited, funding corridors at the expense of other initiatives
may not invariably be the best option.
Corridor Features That Facilitate Faunal
Movements and Plant Dispersal
As mentioned earlier, the efficacy of movement corridors often is assessed
not only as their ability to facilitate individual movement but also as the suc-
cessful establishment of dispersing individuals as breeding members in a new
- Landscape Connectivity and Biological Corridors 55