chapter 26 community ecology (community (succession (climax community…
chapter 26 community ecology
a group of species that occur together at the same time and place.
this more-or-less predictable sequence of changes
the disturbed patch undergoes succession until it becomes spruce-fir forest again, which is the climax community, and stability returns.
such as reintroducing wolves into Yellowstone national park and encouraging the migration of bears and mountain lions across the Rio Grande River from Mexico into Big Bend National Park.
habitat loss and habitat fragmentation
by studying community ecology, we may be able to minimize the damage we do. we already realize that wetlands are extremely valuable; not only do they have high species diversity, but they also filter harmful chemicals out of water, prevent erosion, and produce abundant animal life.
often easier to see than to measure. a first approach to quantifying community diversity is done by measuring species richness, which is simply a count of the species present.
larger areas are more diverse than smaller ones. for example, if we consider the entire earth to be our community, it contains every species, every growth form, and so on, whereas a smaller area-the Americas for example-might still have as many growth forms.
the relationship between area and species richness
species abundance distribution
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optimal foraging theory
examine the interactions between these factors in an attempt ot understand why herbivores eat the plants they do while ignoring others.
optimal diet model
makes four predictions.
resource competition occurs when the organisms actually consume a shared resource, thus making it less available for other organisms.
one organism restricts another organism's access to resources even though the first night not be using it.
if a species can increase from very low population density even with its competitor present, then that species can be invasive
any substance or factor that can lead to increased growth rates as its availability is increased and tha tis consumed by an organism.
thus an increase in one plant species is associated with a decrease in others, and they appear to be in competition. because the plants are not actually competing for and using a resource.
mutualism or mutualistic relationship
if two organisms interact such that both benefit
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