Topic 27

Question 1

Environmental conditions change across landscapes too..

Answer 1

alter community structure across a landscape.

Question 2

Zonation

Answer 2

changes in community structure across a landscape. borders between communities can be abrupt or gradual transition. depends on steep vs. gradual changing environmental gradients

Question 3

Environmental conditions also change through ..

Answer 3

time to alter community structure

Question 4

Succession

Answer 4

change in community structure (at specific location) through time. change in species composition and population dynamics. B and D of species change in response to environmental conditions

Question 5

Community structure varies through time so…

Answer 5

gradient of changes (in same place) occur through time. traditionally through of a transition form bare ground to grassland to shrub land to forest

Question 6

Primary succession

Answer 6

process occurs at a site not previously occupied by a community (rocks, cliffs)

Question 7

Secondary succession

Answer 7

process occurs on a site previously occupied by a community after disturbance (natural fire, flood, cold, meteor)

Question 8

Disturbance

Answer 8

any process that results in the removal (either partial or complete) of the existing community

Question 9

Sand is a product of..

Answer 9

pulverized rock

Question 10

Sand is deposited by..

Answer 10

wind and water (become piled to form dunes)

Question 11

Beach grass functions too..

Answer 11

stabilize the dunes with extensive system of roots.

Question 12

Mat forming scrubs to invade and vegetation shifts to,,,

Answer 12

dominance by trees. 1st pines to 2nd hardwoods.

Question 13

Colonizing species modify the local abiotic conditions and generally

Answer 13

making them less extreme (paving the way) for invasion of other species.

Question 14

Succession involves a pattern of..

Answer 14

species colonization* and extirpation from a specific region with species displaying other spices from community over time

Question 15

Early successional species (pioneer/colonizing species) are ..

Answer 15

first to colonize an area

Question 16

r selected life traits ..

Answer 16

high growth rates, smaller size, short lived, high rates of population growth, high degree of dispersal. can often survival under extreme abiotic conditions but poor competitors

Question 17

Laye successional species (‘climax’ species) replace ..

Answer 17

early successional spices in a community overtime.

Question 18

K selected life traits

Answer 18

slower growth rates, larger size, long lived, low rates of population growth, low degree of dispersal. better competitors but couldn’t colonize because can’t survive under extreme abiotic conditions

Question 19

Our understanding of succession is mainly based on..

Answer 19

plant communities

Question 20

3 succession mechanisms

Answer 20

• facilitation
• inhibition
• tolerance

Question 21

Facilitation

Answer 21

pioneers modify the environment in ways that make it suitable to later species to establish. important in primary succession, but also secondary

Question 22

Inhibition

Answer 22

no one species is competitively superior but which ever arrives first hold the site making it less suitable for other species. species are replaced only as they die (short lived to long lived)

Question 23

Tolerance

Answer 23

later species aren’t suppressed or aided by earlier species. grow, establish and mature independently of other species

Question 24

Some ecologists prefer to focus on ..

Answer 24

attributes rather than mechanisms

Question 25

Community structure typically become..

Answer 25

more complex during succession. species richness tends to peak mid succession. food chains tend to increase in length

Question 26

Biomass and total organic matter increases and progressively more…

Answer 26

nutrients are stored in organic form, greater important on decomposers for the release of nutrients from organic matter

Question 27

Disturbance

Answer 27

any process resulting in removal of existing community

Question 28

Disturbance event

Answer 28

relatively discrete event that disrupts community structure and function (fire, flood)

Question 29

Disturbance regime

Answer 29

pattern of disturbance events that characterize a landscape over longer period of time.

Question 30

Intensity

Answer 30

proportion of a species population that the disturbance kills or eliminates

Question 31

Scale

Answer 31

spatial extent of the impact of disturbance relative to the size of the affected landscape

Question 32

Frequency

Answer 32

mean number of disturbances that occur within a particular time interval

Question 33

Small scale disturbance creates a..

Answer 33

gap which provides access to physical space for colonization by new individuals. often enhances diversity by increasing environmental heterogeneity. (wind storm, death on an individual tree. can occur frequently)

Question 34

Large scale disturbance reduces or eliminates ..

Answer 34

local populations and significantly modifies physical environment then secondary succession (large scale fires, occurs more rarely)

Question 35

Disturbance can both ..

Answer 35

reduce and enhance species diversity

Question 36

Succession is driven by ..

Answer 36

processes of species colonization and extirpation

Question 37

Intermediate disturbance hypothesis 2 theories

Answer 37

1. colonization increases species richness

2. extirpation decreases species richness

Question 38

Extirpation decreases species richness and ..

Answer 38

diversity peaks during middle stages. after arrival or later species but before replacement of early species,

Question 39

Extirpation without disturbance

Answer 39

later species will replace early species (diversity declines)

Question 40

Extirpation with high disturbance

Answer 40

succession is kept at early stages (low diversity)

Question 41

Extirpation with intermediate disturbance

Answer 41

colonization is maintained and competitive replacement is minimal.

Question 42

Intermediate disturbance hypothesis

Answer 42

pattern of high diversity at intermediate frequencies of disturbance

Question 43

Disturbance acts as ..

Answer 43

a reset on a community. reduces size of populations promoting coexistence by reducing competition.

Question 44

Disturbance allows a site to be..

Answer 44

colonized by pioneer species again

Question 45

If disturbance is frequent later successional stages will..

Answer 45

never be reached

Question 46

Traditional view of communities

Answer 46

in a state of equilibrium or stable balance (climax state) unless seriously disturbed.

Question 47

Stability/resilience

Answer 47

tendency of a community to reach and maintain an equilibrium or constant condition regardless of disturbance

Question 48

Reality is most communities often have a ..

Answer 48

certain level of disturbance occurring normally all the time

Question 49

Current thought of communities

Answer 49

communities are generally in a state of recovery from disturbance (not usually climax state)