Chap13 Flashcards
(26 cards)
Landscape ecology
the study of how the spatial patterning of landscapes affects the behavior, populations, and diversity of organisms as well as the functioning of ecosystem
Landscape ecology forms…
the ecological framework around which conservation biologists study the effects of habitat fragmentation
- habitat size
- Edge effects
- connectedness
Habitat fragmentation
an umbrella term describing the complete process by which habitat loss results in the division of large, continuous habitats into a greater number of smaller patches of lower total area, isolated from each other by a matrix of dissimilar habitats, and is not just the pattern of spatial arrangement of remaining habitat
Ecological impacts of habitat fragmentation are complex
patch area edge effects patch shape complexity isolation landscape matrix contrast
Species-area relationship
smaller fragments (islands or patches) harbor fewer species
Species-area relationship can be formalized in the equation
S=cA^z
Where: S=the number of spp A= the area c=a constant z=the rate at which species accumulate as A increases
because relationship is _____ habitat destruction will initially cause only a small percentage of species to become extinct
nonlinear
as habitat loss continues, the rate of species loss _______
increases
Equilibrium theory of island biogeography
states that the number of species within a habitat patch is determined by a balance between local colonization of a new species not already present and local extinction of existing species
Theory of island biogeography: rates
the rate of colonization and extinction depends on island size and degree of isolation
Theory of island biogeography: area
larger areas can support larger populations of each species, so extinction is less likely on large islands than small ones
Theory of island biogeography: distance
islands that are far from sources of colonizing individuals will have lower colonization rates than islands that are close to those sources
Faunal relaxation
reduction in diversity following a reduction in habitat area or the creation of a habitat island within formerly contiguous habitat
Extinction debt
the difference between the large number of species doomed to extinction because of habitat loss and fragmentation and the smaller number of extinctions that have already occurred
habitat fragmentation shifts the colonization-extinction balance in favor of _____
extinction
Process of species loss can take a long time, especially true for ________
long-lived species
Single large or several small (SLOSS) debate
is it possible to maintain more species in a reserve consisting of a single large area or in one consisting of several small areas summing to the same total area?
Answers to SLOSS
it depends
if the smaller patches each represent a unique species assemblage, then several smaller reserves are preferable
if the patches are close to one another and species composition is similar, then a single large reserve is best
In general, reserves should be:
large intact situated close together connected by corridors round contain buffer zones of intermediate use
in reality, land usually gets protected _______
haphazardly
There are also other reasons besides species protection to create reserves
urban nature centers
edge effects
differences in both the environmental and biotic conditions between the edges and the interiors of habitat patches
edge effects conditions
light humidity temperature wind incidence of fire invasive species disease brood parasites
edge effects can greatly reduce the amount of ______
high quality habitat
especially true for fragmented habitats
