Textbook: Chapter 17 - Community Structure

Question 1

Aphotic zone

Answer 1

A deepwater area of marine ecosystems below the depth of effective light penetration

Question 2

Benthic zone

Answer 2

The area of the sea bottom

Question 3

Basal species

Answer 3

Species that feed on no other species but are fed upon by others

Question 4

Canopy

Answer 4

Uppermost layer of vegetation formed by trees; also the uppermost layer of vegetation in shrub communities or in any terrestrial plant community where the upper layer forms a distinct habitat

Question 5

Continuum concept

Answer 5

THe view, first proposed by H.A. Gleason,t hat vegetation is a continuous variable in a continuously changing environment; therefore, no two vegetational communities are identical, and associations of species arise only from similarities in requirements.

Question 6

Community

Answer 6

A group of interacting plants and animals inhabiting a given area

Question 7

Diversity index

Answer 7

The mathematical expression of species richness of a given community or area

Question 8

Dominant

Answer 8

Population possessing ecological dominance in a given community and thereby governing type and abundance of other species in the community

Question 9

Functional type (group)

Answer 9

A collection of species that exploit the same array of resources or perform similar functions within the community

Question 10

Forest floor

Answer 10

Term describing the ground layer of leaves and detritus; site of decomposition

Question 11

Food web

Answer 11

Interlocking pattern formed by a series of interconnecting food chains

Question 12

Food chain

Answer 12

Movement of energy and nutrients from one feeding group of organisms to another in a series that begins with plants and ends with carnivores, detrital feeders and decomposers

Question 13

Guild

Answer 13

A group of populations that utilize a gradient of resources in a similar way.

Question 14

Herb layer

Answer 14

Lichens, moss, ferns, herbceous plants and small woody seedlings growing on the forest floor

Question 15

Individualistic concept

Answer 15

The view, first proposed by HA gleason, that vegetation is a continuous variable in a continuously changing environment; therfore, not two vegetational communities are identical and associations of species arise only from silarities in requirements

Question 16

Intermediate species

Answer 16

Species that feed on other species and they themselves are prey of other species

Question 17

Keystone species

Answer 17

A species whose activites have a significant role in determining community structure

Question 18

Link

Answer 18

In a foodweb, the arrows leading from a consumer to a species being consumed

Question 19

Organismic concept of community

Answer 19

Idea that species, especially plant species, are integrated into an internally interdependent unit; upon maturity and death of the community, another identical plant community replaces it

Question 20

Photic zone

Answer 20

Lighted water column of a lake or ocean, inhabited by plankton

Question 21

Percent base saturation

Answer 21

The extent to which the exchange sites of soil particles are occupied by exhcnagable base cations or by cations other tha hydrogen and aluminum, expressed as percentage of total cation exchange capacity; compare cation exchange capacity

Question 22

Rank-abundance diagram

Answer 22

Plots of relative abundance of each species against rank, defined as the order of species from the most to the least abundant

Question 23

Relative abundance

Answer 23

Proportional representaiton of a species in a community or sample of a community

Question 24

Simpson’s index

Answer 24

A measure of the probability that two individuals randomly selected from a sample will belong to the same species

Question 25

Shannon index

Answer 25

An index of diversity that considers both species richness and evenness

Question 26

Species richness

Answer 26

Number of species in a given area

Question 27

Species evenness

Answer 27

A component of species diversity index; a measure of the distribution of individuals among total species occupying a given area

Question 28

Sorensen’s coefficicent of community

Answer 28

Index of similarity between two stands of communities. The index ranges from 0 to indicate communities with no species in common to 100 to indicate communities with identical sepcies composition

Question 29

Trophic level

Answer 29

Functional classification of organisms in an ecosystem according to feeding relationships, ranging from first-level autrophs through succeeding levels of herbivores and carnivores

Question 30

Top predator

Answer 30

Species not subjected to predators; they prey on intermediate and basal species

Question 31

Understory

Answer 31

Growth of medium-height and small trees beneath the canopy of a forest; sometimes includes a shrub layer as well

Question 32

Zonation

Answer 32

Changes in the physical and biological structures of communities as one moves across the landscape; spatial changes in community structure