{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Study Notes - full set midterm 3

Study Notes - full set midterm 3 - BISC MIDTERM#3 Community...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
BISC MIDTERM #3 10/30/07 Community and Succession - takes about 300 yrs for tropical forest to re-establish itself - dominance: by mass ‘biomass’ , which you can convert in to calories Biodiversity 1) species richness: number of that species per unit area/ volume 2) species diversity: identify and count all of the species. So you have no. of diff species and total number of all of them. You get a value between 0-5 . called the H prime” index. 3) Species ‘evenness’: how many species in an area. Opposite = dominance few species in an area, but big population. Number of species in different geographical locations (breeding of species by latitude). Evolutionary Time : how fast species evolve. Climatic Stability and predictability Spatial Heterogeneity Productivity : e.g more plants produced = more species in each trophic level. (deserts are different, because the productivity of plants etc. aren’t that much, but there are a big number of species.) Competition and Predation : - low intensity of predation = few dominant species there - moderate intensity = large number of species - high intensity = few survivable species. 500 rule: at least have this in a species to avoid ‘inbreeding’. 50: at least this much to have maintainable population. Succession: Replacement of species over time. Each stage of succession = serial stages. 2 concepts of succession - Clements Concept : plant succession development Primary succession: - Plants (mosses) grow on rocks, expands = breaks down into soil over thousands of years. - There are animals living in the mosses (microscopic), which contributes to the ecosystem. Then there will be trees later etc. and soil gets thicker and thicker. Secondary succession: -
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Will edventually reacha climax of community. “climax community” is where it stays for years to come. Gleson says: - succession is a RANDOM process. - Short lived species replaced by long lived species, therefore over time trees in a community are longest living ones. - Competition and Predation determines the outcome of the community. How long does succession last for plant communities? - for weeds etc., just 1 or 2 years. Redwood trees and Douglas Furs - if burned down to the ground, it takes 1000 years to re-establish the community. Tropical Rainforest - takes 300 years to become succession again. Is succession directional? - No. can go everywhere, BUT ends up at the same end point anyway. Stability of Communities: 2 aspects. 1) Resistance: shafforeal burns easily; redwoods are much much harder. 2) Resilience: ability to bounce back. Different kinds of climax communities: - Mono – climax : cold areas. Process of bedrock broken down etc = very slow, since its so cold there. - Poly – climax community: a series of climax communities. Very close to each other. - Dis-climax – when the natural climax community. is prevented; not reached. E.g: sulfuric acid formed in soil near a volcano’s rim/ opening, when the sulfur gas is blown by wind into area around it, thus communities can never reach climax.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}