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High school biology
Community ecology review
Key terms
| Term | Meaning |
|---|---|
| Community | All the populations of all the different species that live together in a particular area |
| Species richness | The number of species present in a community |
| Species diversity | A measure of both species richness and relative number of species |
| Foundation species | Species that plays an essential role in creating and defining a community |
| Keystone species | Species that has a disproportionately large effect on community structure relative to their abundance |
| Invasive species | Non-native species whose introduction causes, or can cause harm in their new area |
| Ecological succession | A series of progressive changes in the composition of an ecological community over time |
| Pioneer species | The first species to populate an area during succession |
| Climax community | Community which has reached a steady state after ecological succession |
Community structure
Community structure describes the composition of a community, and includes the number of species in that community, along with their relative numbers. Different ecological communities can be pretty different in terms of the types and numbers of species they contain.
Communities with the highest species richness tend to be found in areas near the equator, and communities with the lowest species richness lie near the poles.
Larger numbers of species and more even abundances of species lead to higher species diversity. The higher species diversity in a community is, the more stable and able to recover from disturbances that community is.
Several factors that influence community structure include climate patterns, geography, disturbances, and interactions between organisms.
Foundation, keystone, and invasive species
Some species tend to have stronger effects on community structure than others.
Foundation species usually modify the environment so that it can support the other organisms that form the community.
Keystone species generally act in more diverse ways than foundation species, and are more likely to belong to higher trophic levels.
Invasive species may outcompete native species for resources or habitat, altering community structure and potentially leading to extinctions.
Ecological succession
Succession can occur for many different reasons. In most cases, each species affects their environment in a way that allows other species to colonize. Over time, this increases the complexity of the environment, usually increasing species diversity as well.
There are two types of succession, which differ in their starting points:
- In primary succession, newly exposed or newly formed rock is colonized by living things for the first time. Certain hardy plants and lichens with few soil requirements, called pioneer species, colonize the area first.
- In secondary succession, an area that was previously occupied by living things is disturbed, then re-colonized following the disturbance.
Over a long period of time, and assuming no further disturbances, a climax community may form when a community reaches a steady, mature state.
Mistakes and misconceptions
- Not all non-native species become invasive. Invasive species are damaging, or have the potential to be damaging, to their new environment. They displace other species by competing with them, affecting their health, or destroying the habitat.
Want to join the conversation?
How come this article doesn't mention the seral stages?(3 votes)
What is a climax community?(2 votes)
"Community which has reached a steady state after ecological succession" the terms are on the top of the page.(3 votes)
Durante un largo período de tiempo, y suponiendo que no haya más disturbios.¿Se puede formar una comunidad clímax ?(2 votes)- What are the main questions of community ecology?(1 vote)
como no entiendo srry(1 vote)
In my area there's a non native plant. It's not invasive and actually serves the community. Is there a term to describe a helpful non native species?(1 vote)- Are the organisms going to move to a new population(1 vote)
- Are invasive species danger for a habitat?(0 votes)
Yes and no, because they might help soil and vegetation but, they might kill off species.(3 votes)