BIOPL11.11 - 11/11/2008 11:58:00 Community Structure...

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Unformatted text preview: 11/11/2008 11:58:00 Community Structure -structure or spatial distribution of individuals or populations -Large communities have variable vegetation patches, with large transition zones between ecosystems-edges can have difference combination of species than other adjacent patch more variability=more survivability when conditions/environments change transition zones more variability in terms of number of species; survive best on edges of vegetation area example: trees as fences of a neighborhood, some flowers grow there and certain animals can live there Edges are increasing due toe fragmentation Measure Species Diversity Greater diversity in aquatic ecosystems-greater diversity with dept down t 2000 meters then decline Decline in plant life, because sunlight to a certain level Actually more diversity in deep ocean than we thought because it wasnt studied well before The most Species-rich environments are Tropical rainforests Coral reefs Sunscreen may be poisoning coral reefs. When we put sunscreen on and go swimming Deep sea up to 2000 meters Large tropical lakes-tend to have high species richness but low abundance Native Species Natural species, occupied area for long period of time, incorporated in ecosystems Non-native Species moved into system over recent time, can be introduced by humans or natural migration tend to disrupt ecosystem because they are not part of natural ecosystem and have no predators to keep tings in check. Can causes damage Keystone Species Tend to play a vital role in ecosystem. If keystone species is removed, the whole ecosystem can fall apart and crash. Maintain ecosystem Indicator Species Used by ecologist to assess health of ecosystem. Decline in their numbers is indicative of ecosystem in decline First signal of habitat/environmental change Measuring Extinction Rates Curve is not linear, curves and kind of flattens out with a slight increase Y axis: number of species X axis: Area Species/area curves-90% loss in area results in 50% decline in species Getting rid of last 10% then, species =0 Minimum viable population estimates Smallest number of individuals necessary to ensure population survival in region for specific time period Most indicate a dew thousand individuals are necessary for survival beyond a few decades Minimum dynamic area Minimum area required for species to survive (maintain MVP) Most small animals require 100-1000 square km 50 grizzly bears-49,000 sq km o tend to roam Population Viability analysis-risk assessment analysis to determine persistence...
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This note was uploaded on 01/26/2009 for the course BIOPL 2400 taught by Professor Silva,t. during the Fall '08 term at Cornell University (Engineering School).

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BIOPL11.11 - 11/11/2008 11:58:00 Community Structure...

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