Environmental Engineering Reference
In-Depth Information
how species come to occupy different regions of a landscape via two eco-
logical processes: migration across landscapes, and interactions such as com-
petition and predation within local areas (Leibold et al. 2004). The
metacommunity is represented by the set of local species assemblages or
local communities.The constellation of local communities on a landscape
is shaped by the rate of species migrations among locales relative to the
strength and nature of species interactions within a locale.
The metacommunity allows evaluation of another form of diversity,
known as beta (
) diversity.Technically, beta diversity quantifies the rate at
which species compositions turn over or become dissimilar across incre-
mental distances on landscapes. A high turn over rate or high dissimilarity
between adjacent locations implies that the species composition across the
landscape is highly heterogeneous, or is highly diverse.
The implication here is that areas
deemed by humans to be representa-
tive of a certain environmental state
or a local hotspot could very well be
the outcome of landscape-scale
processes that produce a local con-
centration of species rather than,
what is usually implicitly assumed,
that they represent local sources of
diversity for the landscape. Accord-
ingly, a conservation strategy that
creates parks and permits land devel-
opment within the matrix between
parks can disrupt the flow of species across landscapes and alter beta diver-
sity. Moreover, such disruption could eventually doom even the hot spot
species pool to extinction.This insight underscores that effective conserva-
tion requires thinking about protecting dynamic ecological processes lead-
ing to diversity patterns across landscapes, rather than simply identifying and
protecting diversity concentrations locally within landscapes.
β
Beta diversity quantifies the rate at
which species compositions
turnover or become dissimilar
across incremental distances on
landscapes. A high turnover rate
or high dissimilarity between adja-
cent locations implies that the
species composition across the
landscape is highly heterogeneous,
or is highly diverse.
Temporal Dynamics of Habitats
Habitat, being comprised of living organisms, may not persist indefinitely
in any one location (Sinclair et al. 1997). Dominant vegetation in a location
passes through different stages of a developmental cycle including aging,
dying back, and regenerating.This process is known as ecological succes-
