AEC 360 Exam 3

Canopy gaps change local forest composition primarily by increased

Canopy gaps change local forest composition primarily by increased

light

If we assess the number of trophic groups and the abundance of individuals per group in a community, we are measuring

Functional diversity

Net primary productivity is calculated as

GPP – respiration.

Which of the following factors is NOT used for quantifying primary productivity over time?

the change in consumer biomass

What is a meta-community?

A set of local communities linked by the dispersal.

One of the traits common in late-succession plant species is

few seeds.

In aquatic ecosystems, trophic pyramids of biomass are inverted because

the standing biomass of algae is lower than the standing biomass of consumers.

Assimilation energy is the percentage of consumed energy that is

digested and absorbed.

Food web interactions depicted in the figure represent a systems that is 

Top-down controlled

Which diagram represents a food web controlled from the bottom up?

A

The presence of fish has a positive effect on shoreline flowering plants. Which lines in the diagram reflect a negative direct effect?

fish→larval dragonfly

Food chain efficiency is the percentage of _____ from one trophic level compared to the next_____ trophic level.

net production; lower

How does an ecologist determine the presence of an ecotone?

Measure the abundance of plant species over space and abrupt changes in species composition.

The rate at which solar or chemical energy is captured and converted to chemical bonds by photosynthesis or chemosynthesis is called

primary productivity

Keystone species

can affect community structure regardless of population size.

In hiking up a mountain you are likely to pass through various community types as you proceed from the low-elevation lands to the summit. This change in community is called

zonation.

According to Clements, an interdependent community is

A community in which all species depend on each other to exist

In community ecology, what is an assemblage within a community?

All populations of a type of organism (e.g., fishes) living together in a particular area.

Energy that an organism uses to add to its biomass is

assimilated.

Which is an example of an ecosystem engineer?

beavers, which build dams on streams

The biomass of producers in a given area of an ecosystem at a particular moment is called

the standing crop.

What is a trophic guild (local guild)?

Any group of species that exploit the same type of resources within the community.

Which of the following is NOT a low-productivity aquatic ecosystem?

coral reef

A climax community that is not persistent is called a _____ climax community.

transient

The number of species in a relatively small area of homogeneous habitat is called

local diversity.

The average energy residence time is calculated as

energy in a trophic level divided by net productivity.

What community measure does Shannon's index quantify?

species diversity

What accounts for the pyramid shape of the diagram that represents energy in trophic groups in an ecosystem?

Energy is lost as it moves from one trophic level to the next.

Communities with _____ species are _____ stable.

many; more

Succession is change in _____ over time.

species composition

All of the species in all of the habitats that constitute a large geographic area are called

regional diversity.

Primary succession

usually begins with lichens and mosses.

Biomass residence time is the length of time that

biomass spends in a given trophic level.

Regional species diversity is also called _____ diversity.

gamma

A mechanism of succession in which the presence of one species increases the probability that a second species can become established is

facilitation.

The percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level is called _____ efficiency.

consumption

What would be the most likely species richness–productivity relationship for a community in which the species were not resource limited?

negative

The plot shows that most species in this community are

moderately abundant.

Terrestrial primary succession begins with

lichens and mosses.

Which of the following is NOT an example of a habitat that could undergo primary succession?

tree-fall gap

What term describes the total mass of trees, shrubs, herbaceous plants, and grasses present in a given forest on a given day?

standing crop

What is a major distinction between direct and indirect effects in a community?

Indirect effects always include more than two species; direct effects do not.

A researcher removed predatory starfish from sections of intertidal rock and found that the number of prey species decreased by 50 percent relative to control plots within a short time. This indicates that

starfish predation increases prey diversity.

Terrestrial NPP is greatest in _____ ecosystems, and aquatic NPP is greatest in _____ ecosystems.

tropical; coastal

When an animal eats fruit with hard seeds that cannot be digested and are excreted whole as a waste product, the seeds constitute _____ energy.

egested

The study of the balance of nutrients in ecological interactions is called

ecological stoichiometry.

Each stage of community change during succession is called a _____ stage.

seral

Changes in North American forest climax communities

can occur but may happen very slowly.

To apply the concept of chronosequence, ecologists assume that

older sites and younger sites have undergone the same disturbances.

The graph shows the rank-abundance curve for two communities. 

Community B has higher diversity and evenness than community A