Topic 28 Flashcards
Habitat patch
homogeneous area containing suitable conditions and resources needed to sustain a population
Populations of many species (community) occur within a..
habitat patch
Habitat patches are..
heterogeneously distributed over landscape separated by unsuitable habitat (results in many local isolated communities)
Local communities may interact through..
dispersal (emigration and immigration)
Degree of interaction (dispersal) depends on
ability storage disperse between habitat patches
Landscape ecology
study of the causes and consequences of the spatial variation
Landscapes are a collection of
communities that exist as patchwork assembly called mosaic
Landscape ecology focus on..
features such as distribution, shape, and spatial arrangement of patches.
Naturally occurring patches reflect ..
regional variations in geology, topography, soil and climate. (conducted at different scales)
3 Landscape ecology basis
- landscape composition
- landscape structure
- landscape scale
Landscape structure includes
- large vs small patches
- how dispersed patches are
- shape of patches
- how fragmented the landscape is
Landscape scale includes
- grain
- extent
Grain =
smallest homogenous unit that is the focus of the study
Extent =
total area/time period covered
Island biogeography theory
larger islands (habitat patch) hold more spices than smaller islands
Number of species on an island (habitat patch) is determined by dynamic equilibrium between..
- colonization (immigration) of species to island
- extirpation of species from the island
As the number of species increase..
the rate of species successfully colonizing decreases because early arrivals use up available habitats and resources (fundamental niches)
As the number of species increases..
the rate of species being extirpated increases due to competition increases (Completely dominant species outcompete otherS)
Equilibrium species richness (S) is reached when
colonization = extirpation (species richness is stable but species composition can change)
Distance between islands (habitat patches) and island size influences..
colonization, extirpation rates and equilibrium species richness(S)
1st prediction for island biogeography theory
-as the distance between patches increase the colonization rates will decrease leading to lower S per patch. species become less likely to successfully make journey as distance increases
2nd prediction of island biogeography
-larger patch of island will have lower rates of extirpation leading to higher S. more resources and available habitats on lager island , smaller patches will have lower S
Application of IBT
important cause anthropogenic extinction is because of habitat destruction/loss.
Habitat destruction results in
highly fragmented landscapes leaving much smaller habitat patches that are farther apart relative to natural conditions.
In fragmented landscapes ..
apply IDT to determine size of patches and distance between patches appropriate to maximizing biodiversity
Human activities fragment existing patches into..
smaller and more isolated patches. conversion to grassland and forests to agriculture. roads/infrastructure, settlements
Each habitat patch is composed of..
- interior
- edge or border
Interior
habitat has its own environment conditions and community structure
Edge or border (transition zone)
where community structure and environmental conditions of adjacent patches are blended.
Edge effect
diverse environmental conditions allow edges to support high species diversity
Interior species
requires stable environmental conditions of interior habitats, no abrupt changes
Edge species
can survive under unstable conditions with edge habitat
Size and shape of patches together affect the..
edge:interior habitat ratio
As patch size increases..
edge: interior habitat decreases.
- small patch mostly edge habitat,
- larger patch mostly interior habitat
As patch width increases..
edge: interior habitat decreases.
- long narrow, mostly edge habitat
- square, circle, mostly interior habitat
As the ratio of edge:interior habitat changes ..
should have higher diversity with increasing edge habitat but only if interior habitat remains
Transition zones
patches border each other creating transition zones (Edges) from one patch to the next. area of contact, separation and transition connect patches allowing flows of energy, material and organisms
Corridors
connect different patches together. strips of habitat that contain favourable conditions. contain similar vegetation to the patches they connect or contain similar conditions
Corridors act as..
travel lanes connectedly subpopulation and aid in colonization of new patches
Corridors important in landscape dominated by human activities and ..
road partition and fragment populations alter movement, reproduction, induce stress and increase mortality
Artificial corridors may be one solution to ..
reconnect populations. bridges contain vegetation to mimic natural habitat
Ecosystem management in general for..
preserving endangered interior species
Best spatial configuration for core natural area
- larger is better than smaller
- closer together is better than farther apart
- better if connected by habitat corridors
- compact shapes are better for minimizing boundary length
- buffer zone is preferable
