1 / 15

Section 4 – Community Stability

Section 4 – Community Stability. Ecological Succession. Equilibrium : stable and balanced Disequilibrium : unstable and off balance Limiting factors shift – carrying capacities altered Population sizes change Succession : a somewhat predictable series of changes over time in a community

preston-raymond
Télécharger la présentation

Section 4 – Community Stability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Section 4 – Community Stability

  2. Ecological Succession • Equilibrium: stable and balanced • Disequilibrium: unstable and off balance • Limiting factors shift – carrying capacities altered • Population sizes change • Succession: a somewhat predictable series of changes over time in a community • Following a Disturbance • Ex. Fire, Flood, Natural Disasters

  3. Primary Succession • Primary Succession: the somewhat predictable series of changes in a community that follows a disturbance so severe that no vegetation or soil life remains • Starting from scratch – from rock, sand or sediment • Glaciers retreat, lakes dry up, volcanic lava or ash spreads across a landscape • Pioneer Species: one of the first species to colonize newly exposed land • Well adapted for colonization • Seeds can travel long distances to spread quickly

  4. Primary Succession • Lichens: formed by a mutualistic relationship between algae and fungi • Algae provides food and energy – photosynthesis • Fungi holds onto rocks and captures moisture • Lichen grows – releases acid the breaks down rock • Soil begins to form, small plants, insects and worms move in

  5. Secondary Succession • Secondary Succession: the somewhat predictable series of changes in a community that follows a disturbance (e.g., a fire, logging, or farming) that dramatically alters the community but does not destroy all vegetation or soil life • Occurs faster than primary succession

  6. Succession in Water • Primary Aquatic Succession: when an area fills with water for the first time • Glaciers retreat and leave depressions in the ground • Over time, aquatic communities are established • Secondary Aquatic Succession: follows disturbance to aquatic community • Pond fills with organic matter • Pond may fill in completely, and a terrestrial system begins

  7. Climax Communities • Climax Community: stable community that “completes” the succession process • Climate, Soil Conditions and other factors influence a community’s composition • These factors can also promote or inhibit a community’s progression between succession stages. • Communities – temporary, ever-changing associations among species

  8. Invasive Species • Invasive Species: a nonnative (exotic) species that spreads widely in a community • A community DISTURBANCE. • Do not have sufficient limiting factors, and end up taking over.

  9. What makes a species Invasive? • Some nonnative species are NOT invasive • Populations remain Small and Localized, eventually dying out. • Others exist without causing problems • Invasive when limiting factors are not present in their new environment. • Limiting Factors: predators, parasites, competitors • Population growth of exotic species is not held in check. • Community thrown out of balance.

More Related