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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
6 types of disturbances
- fire - windstorms - floods - deforestation - disease epidemics - herbivore outbreaks
26
intermediate disturbance hypothesis
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
ecological succession
recovery of communities after a severe disturbance - transformation of communities over time
28
ways of chronosequencing
- pollen in lake/pond sediments - fossils - carbon dating
29
primary succession
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
primary succession are colonized by...
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
Secondary succession
- 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
terrestrial succession
sequence of seral stages that a site passes on its way to a climax community can differ depending on the initial conditions.
33
Similar sites can pass through different ___ stages due to variation in ____________.
- seral stages - variation in historic abiotic conditions, soil fertility, and disturbances
34
chronosequence assumes that...
older and younger sites pass through similar serial stages - this assumption is not always met
35
The best approach to analyzing succession is to use a combination of methods, including....
chronosequence's, pollen records, and long- term studies of single sites
36
animal succession
Changes in the plant community can change the habitats that are available to animals - causes changes in the animal community
37
succession of intertidal communities
succession in intertidal communities can occur rapidly after a disturbance due to short generation time of dominant species
38
why can intertidal communities recover rapidly?
after a disturbance, the populations will experience rapid succession, due to short generation time of dominant species
39
stream succession
rapid succesion; organisms move downstream (away from more disturbed sites) - quicker moving streams do not have submerged vegetation
40
type of extreme disturbance streams can face
heavy rainfall - increases volume and speed of water - causes sand and rocks to move downstream (killing/wiping out plants, animals, and algae downstream)
41
heterotrophic river
respiration > photosynthesis
42
autotrophic river
photosynthesis > respiration
43
rivers always start as...and usually end as...
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
lake/pond succession occurs at...
slow transformation rates
45
most lakes are...
oligotrophic (nutrient-poor) - little submerged vegetation
46
mesotrophic
lake w/ more nutrients than oligotrophic - some submerged vegetation
47
eutrophic lake
lots of nutrients (fish die-off from bacteria digesting algae and lack of CO2) - LOTS of nitrogen and phosphorous - LOTS of submerged vegetation
48
lake succession: model 2: years w/ little succession, w/ episodes of rapid change
- 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
Succession does NOT always produce...
a single climax community.
50
in early stages of succession, abiotic conditions are...
rapidly altered - once a community contains the largest plants it can support, changes will occur more slowly
51
When environmental conditions are stable, the composition of plant species in a community...
also becomes stable -the species in a climax community can continue to change.
52
When environmental conditions are stable, the species in a climax community can....
continue to change
53
as one moves along an environmental gradient, composition of ___ can ____
composition of climax communities can vary
54
Except for oceans, most aquatic systems are...
considered temporary (NOT climax community) - all receive inputs of soil particles and organic matter from surrounding land
55
routine lake succession (model 1)
gradual filling of shallow bodies of water - roots/stems accumulate below water
56
Small-scale disturbances in an area with a climax community can allow growth of...
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
Climax Community Characteristics
- Maintain species diversity for extended time - Multiple specialized ecological niches - High level of organism interactions - Nutrients recycled & biomass levels remain constant
58
The only thing differentiating a climax community from a successional community is...
time scale
59
After a disturbance occurs, a succession of species and communities...
replaces the individuals that were lost
60
The composition of a community is primarily a function of...
climate and history
61
Jaccard's index measures...
how similar 2 communities are
62
Jaccard's index equation:
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
Jaccard's index range:
0-->1 - 0 = no species in common - 1 = identical species composition
64
succession depends on...
the ecosystem - habitat - environment - climate

Ecology (33 decks)

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