Lecture 21 CH 58 - Communties and Ecosystems on Large Scales

Community

Grouping of many populations that live in the same place at the same time

Community ecology

Studies the factors that influence the number and abundance of species in a community

Ecosystem

System formed by the interaction between a community of organisms and its physical environment

Ecosystem ecology

Studies the flow of energy and the production of biomass(total mass of living matter in a given area)

Species richness

Number of species in each community and number of species of most taxa varies according to geographic range

Species-time hypothesis

The proposal that temperate regions have less species rich communities than tropical ones because they are younger

Species-area hypothesis

The proposal that larger areas contain more species than smaller ones because they can support larger populations and a greater range of habitats

Species area effect

The observation that the number of species tends to increase with the amount of available area

Species productivity hypothesis

The proposal that greater production by plants results in greater overall species richness

Evapotranspiration rate

The rate at which water moves into the atmosphere through the processes of evaporation from the soil and other surfaces and transpiration by plants

Relative abundance

How common a species is compared to others in the community

Species diversity

A measure of biological diversity that incorporates both the number of species in an area and the relative distribution of individuals among species

Shannon diversity index (Hs)

A means of measuring the diversity of a community using the formula

Effective number of species

A measure of diversity that converts values from species diversity indices into equivalent number of species

A community is stable when there is a little to no change in

-# of species

-their abundance

-community in equilibrium

Eltons diversity stability hypothesis

Disturbances in a species-rich community would be cushioned by large numbers of interacting species and would not produce as drastic an effect as it would on a less diverse community

Succession

The gradual and continuous change in species composition of a community following a disturbance

Primary succession

Succession on a newly exposed site that has no biological legacy in terms of plants animals or microbes

Secondary sucession

Succession on a site that has previously supported life but has undergone a disturbance

Climax community

A distinct end point of sucession

Facilitation

A mechanism for succession in which a species facilitates or make the local environment more suitable for subsequent species

Inhibition

A mechanism is for sucession in which early colonist exclude subsequent colonists

Tolerance

A mechanism for succession in which any species can start the succession, but the eventual climax community is reached in a somewhat orderly fashion; early species neither facilitate nor inhibit subsequent colonists.

Competition intolerant

Species appear later and at climax

Competition tolerant

Species appear later and at climax

Key distinction between three models is in the manner succession proceeds

Facilitation - species replacement facilitated by previous colonist

Inhibition - species replacement is inhibited by previous Colonist

Tolerance - species replacement is unaffected by previous colonists

Equilibrium model of island biogeography

A model that explains the process of succession on new islands, proposing that the number of species on an island tends toward an equilibrium number that is determined by the balance between immigration rates and extinction rates.

Predictions of island biogeography model

-species area effect

-species distance relationship

-species turnover

Species area effect

Number of species should increase with increasing island size

Source pool

The pool of potential species available to colonize an island

Food chain

A linear depiction of energy flow between organisms with each organism feeding on and deriving energy from the preceding organism

Trophic level

Each feeding level in a food chain

Autotrophs (primary producers)

Harvest light or chemical energy and stores it in carbon bonds

Herterotrophs

Eat other organisms

Primary vs secondary consumers

Primary - eat primary producers - herbivores

Secondary - eat primary consumers - carnivores

Tertiary consumers

An organism that feeds on secondary consumers also called a secondary carnivore

Detritus

Unconsumed plants that die and decompose, along with the dead remains of animals and animal waste products

Detritvore

An organism that gets it energy from consuming detritus

Food web

A complex model of interconnected food chains in which there are multiple links among different species

Production efficiency

The percentage of energy assimilated by an organism that becomes incorporated into new biomass

Tropic level transfer

The amount of energy at a trophic level that is acquired by the trophic level above and incorporated into biomass

Ecological pyramids

Pyramid of numbers, biomass, energy

Pyramid of numbers

A graphic representation of trophic levels in a food web in which the number of individuals decreases at each trophic level, with a large number of individuals at the base and fewer individuals at the top.

Pyramid of biomass

A graphic representation of trophic levels in a food web in which the organisms at each trophic level are weighed.

Biomass

Is the estimate of the total mass of living matter in a given area, usually measured in grams per square meter

Pyramid of energy

A graphic representation of trophic levels in a food web in which rates of energy production are used rather than biomass.

Gross primary production (GPP)

The measure of biomass production by photosynthesis organisms equivalent to the carbon fixed during photosynthesis

Net primary production (NPP)

Gross primary production minus the energy lost in plant cellular respiration

Primary production

Production by autotrophs normally green plants

Nutrient

Any substance that is metabolized by or incorporated into a living organism and is required for survival, growth, development, tissue repair, or reproduction.

Limiting factor

A factor whose amount or concentration limits the rate of biological process or a chemical reaction

Liebig law of minimum

The principle that states that species biomass abundance is limited by the scariest factor

Upwelling

In the ocean, a process that carries mineral nutrients from the depths to the surface

Primary productivity varies

Highest in tropical rainforests