Chapter 13: Communities Through Time Flashcards
Define “community”
A group of interacting species in the same location
Define “climax community”
A predictable and permanent assemblage of species that occurs in a location after a long period of succesion.
Describe “environmental gradient”
A change in the abiotic conditions across distance in a landscape.
Clementian View
- Species in a particular community worked together over time to facilitate a shift in community composition toward the climax version of that community, and once the climax is reached it would be stable for thousands of years.
- All species within a community responded in the same way to environmental gradients
- There should be sharp boundaries between communities, with little overlap in plant species distributions among communities
- Coevolution and close interactions create interdependencies between plant species that lead to predictable sets of co-occurring species and distinct and separate plant communities with fairly sharp boundaries dividing them
Describe Clements’s “climax communities”
co-evolved
clearly identifiable
largely unchanging in their species composition
Gleason’s View
An individualistic concept of plant associations suggests that species respond to environmental factors according to their own unique physiology. Thus, species do not consistently co-occur.
Biome
A biome is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. Biomes may span more than one continent. A biome encompasses multiple ecosystems within its boundaries.
True or False
Plant communities shift in composition across climate or soil gradients
True
Define (ecological) “succession”
The series of changes in a community through time at a particular location that occur in a fairly predictable way as the location goes from bare rock or lifeless water to being filled with interacting species.
Define “sere”
A plant community at a particular point in the process of succession.
Each sere is distinguished by…
dominant plant species
Plant successional processes correspond with changes to…
animal, fungal, bacterial and protist communities as well
Succession starts with
the initial colonization of a new habitat or follows a disturbance event such as flood, fire or bulldozing.
Define “primary succession”
The temporal sequence of changing communities that begins on substrates containing no organisms and no organic material, meaning that the community assembles completely from scratch.
Define “secondary succession”
The temporal sequence of changing communities that occurs on already established soils following a disturbance from the previous habitat.
