Environmental Engineering Reference
In-Depth Information
sion.Thus, landscapes may be considered mosaics of habitats that locally
fluctuate among successional stages. So, the exact location of a particular de-
velopmental stage of habitat will vary in time. So too will the animal species
composition as species move across the landscape to follow the changes in
habitat. High beta diversity can arise in this case because different animal
species associate with these different successional habitat stages.
Thus, a park or protected area strategy that safeguards a fixed parcel of
land in one location may doom its species to extinction simply because it
ignores the consequences of successional change. One solution then is to
actively manage to arrest succession. But arresting succession will require
“fighting nature” and history has repeatedly shown us that humankind is
doomed to lose at this game. How then do we work with nature? We do
this by thinking about habitat and biodiversity conservation in the context
of landscape-scale habitat renewal (Sinclair et al. 1995).
Habitat of a specific type in a specific location is lost over time because
of the natural ecological processes described above, but the rate of habitat
loss can be exacerbated by exploitation. If habitat facing exploitation is pre-
served at a particular time, such preservation will slow the decay rate. But,
it will still decay. So, parks and protected areas are essential because they buy
time. But, to maintain a constant availability of habitat, we must actively plan
for renewal across the landscape within and outside of protected areas.
The idea of including habitat renewal in conservation derives from the
fundamental principles of population processes presented in chapter 4.
Namely, a population remains at an equilibrium if birthrate exactly balances
death rates.We can extend this simple concept to this case by recognizing
that habitat decay is effectively a form of mortality.Thus, habitat of a par-
ticular type will be preserved if the habitat decay rate is exactly balanced
by habitat renewal. So, the decay rate and the renewal rate determine how
much habitat can be saved in perpetuity—a form of sustainable manage-
ment. But, unlike population birth and death processes that may occur si-
multaneously within a locale, habitat decay and renewal occur in different
locations on a landscape. Moreover,
to maintain habitat, we must either
replace it before or (at the very least)
at the same time as other portions of
the habitat are exploited or decay.
The implication here is that long-
term conservation requires a portfo-
Habitat of a particular type will
be preserved if the habitat decay
rate is exactly balanced by
habitat renewal.
