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ecology > ch. 19: community succession > Flashcards

ch. 19: community succession Flashcards

1
Q

succession

A

process by which species composition of community changes over time
- can take weeks, months, or hundreds of years

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2
Q

seral stage

A

each stage of community change during process of succession

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3
Q

pioneer species

A

earliest species to arrive at site
- usually have ability to disperse long distances and arrive quickly at a disturbed site

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4
Q

climax community

A

final seral stage in process of succession
- generally composed of group of organisms that dominate in a biome

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5
Q

2 ways to observe succession:

A

direct observations (easiest way), indirect observations

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6
Q

chronosequence

A

sequence of communities that exist over time at a location
- when direct observations is not possible

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7
Q

primary succession

A

development of communities in habitats devoid of plants and organic soil
- colonized by species that require no soil and can live on the surfaces of rocks and sand
- ex: sand dunes, lava flows, bare rock

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8
Q

secondary succession

A

development of communities in habitats that have been disturbed and include no plants but still have organic soil
- ex: abandoned agricultural fields

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9
Q

3 mechanisms of succession

A

facilitation, inhibition, and tolerance

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10
Q

facilitation

A

presence of 1 species ↑ probability that a 2nd species can become established

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11
Q

inhibition

A

1 species ↓ the probability that a 2nd species will become established

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12
Q

tolerance

A

probability that a species can become established depends on its dispersal ability and ability to persist under physical conditions

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13
Q

priority effect

A

arrival of 1 species at a site affects subsequent colonization of other species

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14
Q

transient climax community

A

climax community that is not persistent
- frequently disturbed sites = climax community can’t persist
- ex: small wetlands

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15
Q

fire-maintained climax community

A

successional stage that persists as final seral stage due to periodic fires
- Biomes in which fires occur at regular intervals favor the persistence of fire-tolerant species

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16
Q

grazer-maintained climax community

A

successional stage persist as final seral stage due to intense grazing
- Grazers consume the most palatable plants, leaving behind less palatable or better-defended species
- ex: plants won’t eat cheatgrass (inedible) AND cheatgrass is fire resistance, so cheatgrass = climax community

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17
Q

Frederick Clements view on biological communities:

A
  • communities are stable, integrated, and orderly entities with a highly predictable composition
  • communities develop by passing through a series of predictable stages dictated by extensive interactions among species and this development culminates in a stable final stage called a climax community
  • Closed community
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18
Q

Henry Gleason believed that…

A
  • a community found in a particular area is neither stable nor predictable
  • it is largely a matter of chance whether a similar community develops in the same area after a disturbance occurs
  • Open Community
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19
Q

Clements vs Gleason- who was more correct?

A
  • Clements’s position was too extreme
  • Gleason’s view is more correct
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20
Q

clement hypothesis

A

identical communities will always develop in identical environments

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21
Q

Gleason hypothesis

A

identical communities will not always develop in identical environments

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22
Q

disturbance definition

A

an event that removes some individuals or biomass from a community

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23
Q

disturbance always…

A

alters some aspect(s) of resource availability

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24
Q

impact of a disturbance is based on (3 things):

A
  • type of disturbance
  • frequency
  • severity
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25
Q

6 types of disturbances

A
  • fire
  • windstorms
  • floods
  • deforestation
  • disease epidemics
  • herbivore outbreaks
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26
Q

intermediate disturbance hypothesis

A

biodiversity is highest when disturbances are not rare or frequent (disturbances occur at an intermediate rate)
- low disturbance = exclusion
- high disturbance = only tolerant survive

27
Q

ecological succession

A

recovery of communities after a severe disturbance
- transformation of communities over time

28
Q

ways of chronosequencing

A
  • pollen in lake/pond sediments
  • fossils
  • carbon dating
29
Q

primary succession

A

development of communities in habitats that are initially devoid of plants and organic soil, such as dunes, lava flows, and bare rock
- ONLY on ROCK
- must start from “scratch”
- where no plant has gone before

30
Q

primary succession are colonized by…

A

species that require no soil and can live on rocks
- early colonizers produce organic matter to create soil (more hospitable for other species)
- ex: algae, lichen, mosses

31
Q

Secondary succession

A
  • development of communities in disturbed habitats that contain no plants but still contain organic soil
  • specific sequence of species that appears over time is the successional
    pathway
  • ex: plowed fields, forests harmed by hurricane, etc.
32
Q

terrestrial succession

A

sequence of seral stages that a site passes on its way to a climax community can differ depending on the initial conditions.

33
Q

Similar sites can pass through different ___ stages due to variation in ____________.

A
  • seral stages
  • variation in historic abiotic conditions, soil fertility, and disturbances
34
Q

chronosequence assumes that…

A

older and younger sites pass through similar serial stages
- this assumption is not always met

35
Q

The best approach to analyzing succession is to use a combination of methods, including….

A

chronosequence’s, pollen records, and long- term studies of single sites

36
Q

animal succession

A

Changes in the plant community can change the habitats that are available to animals
- causes changes in the animal community

37
Q

succession of intertidal communities

A

succession in intertidal communities can occur rapidly after a disturbance due to short generation time of dominant species

38
Q

why can intertidal communities recover rapidly?

A

after a disturbance, the populations will experience rapid succession, due to short generation time of dominant species

39
Q

stream succession

A

rapid succesion; organisms move downstream (away from more disturbed sites)
- quicker moving streams do not have submerged vegetation

40
Q

type of extreme disturbance streams can face

A

heavy rainfall
- increases volume and speed of water
- causes sand and rocks to move downstream (killing/wiping out plants, animals, and algae downstream)

41
Q

heterotrophic river

A

respiration > photosynthesis

42
Q

autotrophic river

A

photosynthesis > respiration

43
Q

rivers always start as…and usually end as…

A

start: heterotrophic
- initially not large amounts of photosynthesis/plant life
end: autotrophic
- longer life = erosion and mud; less submerged vegetation (no light) = less photosynthesis

44
Q

lake/pond succession occurs at…

A

slow transformation rates

45
Q

most lakes are…

A

oligotrophic (nutrient-poor)
- little submerged vegetation

46
Q

mesotrophic

A

lake w/ more nutrients than oligotrophic
- some submerged vegetation

47
Q

eutrophic lake

A

lots of nutrients (fish die-off from bacteria digesting algae and lack of CO2)
- LOTS of nitrogen and phosphorous
- LOTS of submerged vegetation

48
Q

lake succession: model 2: years w/ little succession, w/ episodes of rapid change

A
  • drought (dries up)
  • new plants colonize bottom of lake (from bottom up)
  • as drought ends, lake fills and plants detach from bottom
  • sediments eventually fill basic and plants float to surface
49
Q

Succession does NOT always produce…

A

a single climax community.

50
Q

in early stages of succession, abiotic conditions are…

A

rapidly altered
- once a community contains the largest plants it can support, changes will occur more slowly

51
Q

When environmental conditions are stable, the composition of plant species in a community…

A

also becomes stable
-the species in a climax community can continue to change.

52
Q

When environmental conditions are stable, the species in a climax community can….

A

continue to change

53
Q

as one moves along an environmental gradient, composition of ___ can ____

A

composition of climax communities can vary

54
Q

Except for oceans, most aquatic systems are…

A

considered temporary (NOT climax community)
- all receive inputs of soil particles and organic matter from surrounding land

55
Q

routine lake succession (model 1)

A

gradual filling of shallow bodies of water
- roots/stems accumulate below water

56
Q

Small-scale disturbances in an area with a climax community can allow growth of…

A

species that are not considered climax species
- ex: break in tree canopy (climax tree species die); lots of plants colonize to try and get sunlight (competition for sunlight)

57
Q

Climax Community Characteristics

A
  • Maintain species diversity for extended time
  • Multiple specialized ecological niches
  • High level of organism interactions
  • Nutrients recycled & biomass levels remain constant
58
Q

The only thing differentiating a climax community from a successional community is…

A

time scale

59
Q

After a disturbance occurs, a succession of species and communities…

A

replaces the individuals that were lost

60
Q

The composition of a community is primarily a function of…

A

climate and history

61
Q

Jaccard’s index measures…

A

how similar 2 communities are

62
Q

Jaccard’s index equation:

A

J = X / (A+B+X)
- X = # of species in BOTH communities
- A = # of species in ONLY community (A)
- B = # of species in ONLY community (B)

63
Q

Jaccard’s index range:

A

0–>1
- 0 = no species in common
- 1 = identical species composition

64
Q

succession depends on…

A

the ecosystem
- habitat
- environment
- climate

ecology (33 decks)

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