BIS 2B Lecture Notes - Lecture 21: Pioneer Species

• School: UC-Davis
• Department: Biological Sciences
• Course: BIS 2B
• Professor: Mark Schwartz; Sharon Strauss

Document Summary

Communities: collections of species that live in the same space. Composition changes as new species invade and existing species resist invasion. Succession: predictable change in species composition through time. Primary: no topsoil, no macro-organisms; created by lava flows so no species have lived there already. Secondary: occurs where species have already lived and have been disturbed, forest fire. Climatic: happens over hundreds of years driven by long term climate change. Facilitation: pioneer species is necessary to modify the environment before later species can colonize. If species a facilitates b, then by removing a, we get less b. Inhibition: pioneer species make the environment less suitable for later species. If species a inhibits b, then by removing a, we get more b. Neutral/tolerance: early species have no effect on later species, species sequence is due entirely to life history. If we remove a, no effect on b.