11. Communities are Always Changing Flashcards
What is “succession” in an ecological context?
directional and continuous patters of colonization and extinction at a site, (not random changes)
Why does succession happen?
changes in resources and microclimate (ex. ecological niches)
What is primary succession?
development from barren land, includes the development of the pioneer species
What are the steps in secondary succession?
pioneer species (they get there faster than others) -> intermediate species -> climax community
What does secondary succession of an oak and hickory forest entail?
pioneer species: annual plants grow and are succeeded by grasses and perennials
intermediate species: shrubs, then pines, and young oak and hickory begin to grow
climax community: the mature oak and hickory forest remains stable until the next disturbance
What do balance and flux mean pertaining to nature?
balance of nature: disturbance is infrequent
flux of nature: disturbance is frequent (this is the state most communities are in)
What is the intermediate disturbance hypothesis?
no disturbance: climax community, high biodiversity (but not the highest - natural disturbance keeps biodiversity high)
too much disturbance: pioneer species, low biodiversity
How do humans affect disturbances in forests?
our suppression of fires means less disturbances in forests
we started putting out too many fires and this resulted in an accumulation of ‘fuel’ that has turned into a major wildfire issue
Are fires good for biodiversity?
small fires are because they are able to get rid of the ‘fuel’ without restarting (primary) succession
How did fires occur in a pre-colonial world?
Indigenous peoples knew what we had to learn the hard way, they actively managed the land via controlled fires
What are the implications of this lesson?
the active management of parks is often required
communities can rebound from natural disturbance so they can also rebound from human disturbance