Ecology Final Unit 3

Is it possible to study an entire community?

No

What kinds of questions are asked at the community level?

What explains patterns of community structure across many lakes in a landscape? Why do lakes vary in terms of how many species are present?

Guild

A guild is a group of species that use the same resources, even though they may be taxonomically distant.

Functional Group

A group a subset of a community that includes species that function in a similar way but may not use the same resources

What mechanisms regulate ecological communities?

Speciation, immigration, immigration, extinction

What are Alpha, beta, and gamma diversity?

Measures of species richness

Alpha

local number of species in a small area of homogeneous habitat

Beta

Number of species turnover between habitats

Gamma

 Regional total number of species in all habitats within geographic area

How do you calculate the Shannon index?

Add all species up, Figure out species proportion by dividing individual # by total number of individuals. Get the natural log of each species proportion. Round to the third place and find the sum. The higher the value, the better the species evenness.

What is a rank abundance curve?

This curve plots the proportional abundance of each species relative to the others.

What is a species accumulation curve?

This curve is the species richness plotted as a function of total number of individuals counted. They help determine when most or all the species in the community have been observed. 

Clemensian Ideas of Communtiy structure

This person believed that species in communities were incredibly interdependent.

Gleason ideas of community structure

Species will adapt to environment. Ecotones.

Are all species equally important? Know about keystone species and dominant species.

Yes all species are important because any species dying out could result in trophic levels becoming messed up. Keystone species are an especially important species as they have a disproportionally large impact on the environment relative to their abundance. Keystone species could be ecosystem engineers, dominant species, predators etc.

What is a trophic cascade?

A carnivore eats an herbivore and it indirectly affects another organism.

How do species interactions restrict or enhance the presence of other species?

If a predator eats an herbivore than more primary producers grow. If a predator dies out, herbivore abundance will rise and primary producers will go down.

Direct vs indirect trophic interactions

Direct is between two species (predation, competition). Predator eats prey.

Indirect is two species need a third or more species. less prey. Predator eats prey- prey doesn’t eat plants, plant abundance rises

Food chains vs food webs vs interaction webs

Food chains are one representation of a few species. Food webs show all interactions and connections.

Ecotone

The area where two ecosystems meet

Ecosystem Resistance

An ecosystems ability to maintain community structure as well as nutrient and energy fluxes (aka ecosystem function) in spite of disturbance

Ecosystem Resilience

The capacity of an ecosystem to return to a pre-disturbed state; ability to recover from disturbance that exceeds resistance.

Succession

Change in species composition in communities over time. Species start out very simple and hardy. Gradually become more niche and complicated

Primary succession

No soil or life at all

Secondary succession

Some soil and life (fires)

What factors lead to succession?

Fires, volcanos, glaciers melting, etc

Assimilated Energy/ Efficiency

The portion of energy that a consumer digests and absorbs. Assimilation/ ingestion

Energy is lost in the form of

Heat

Primary productivity/ production

NPP= GPP- Respiration

How can we measure NPP?

CO2, biomass harvest, isotopes, carbon flux

Where is NPP the greatest on Earth?

The ocean

Where is carbon stored?

Rocks and biomass

What determines the amount of primary productivity?

Light, temperature, nutrients, water

Eutrophication

Excess of nitrogen gets into aquatic ecosystem, blooming plants/ algae which use all the oxygen in the water.

Trophic Pyramid

A chart composed of rectangles that represent the amount of biomass or energy in each trophic group

What is HANPP

Human Appropriation of Net Primary Productivity

Net Secondary productivity

The rate a consumer accumulates biomass in a given area

Egested Energy

the portion of consumed energy that is excreted or regurgitated

Respired Energy

the portion of energy a consumer uses for respiration

Exploitation Efficiency

ingested/ total available.

Production efficiency

Production/assimilation

Trophic efficiency

All energy combined

“Normal” trophic efficiency

Lose 80-90% energy each level

How can we use trophic efficiencies to understand the diets, population sizes, and other information about previous generations of organisms (including t-rex)

How much energy/ food is needed for certain amount of biomass

Biogeochemical cycle

The cycle of physical, chemical and biological factors that influence movement and transformation of chemicals

Sedimentary chemical cycle

Minerals released from rocks. Magnesium, phosphorus, etc

Gaseous cycle

Aerosols in the atmosphere. Nitrogen, carbon

Carbon pools

Fossil fuels, atmosphere, plants and soils, the ocean

Carbon fluxes

Plant and soil respiration, burning fossil fuels, photosynthesis, deforestation, ocean uptake and loss.

Nitrogen stores

The atmosphere and biomass

Phosphorus stores

Fresh water, detritus, sediments, atmosphere

When would nitrogen be limiting?

In early primary succession. No organic matter so no Nitrogen

When would phosphorus be limiting?

In later successional stages. Phosphorus can combine with other elements and become unavailable as nutrients (occlusion).

How do beavers contribute to global warming?

Increase flooding or melting of permafrost which release more methane into the atmosphere