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ecology exam 2 and 3 > module 14 > Flashcards

module 14 Flashcards

1
Q

Communities are in

A

constant flux

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2
Q

communities appear

and what changes

A 
Appear stable in short-term
Change over Long-Term
Environmental Conditions
Competition 
Facilitation
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3
Q

community development is

A

chaotic, cyclical, or directional (succession)

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4
Q

Succession

A

Gradual, Ordered, Directional change in plant and animal communities in an area following a disturbance or the creation of new substrate

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5
Q

Basic Succession – F.E. Clements

A

follows orderly series of species replacement

does not guarantee outcome (single climax)

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6
Q

Primary Succession

A

Sequence of communities developing in newly exposed habitat devoid of life

Succession only from Immigrants

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7
Q

Secondary Succession

A

Sequence of communities developing in habitats in which the climax has been disturbed or removed

Succession from Immigration or Seed Bank

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8
Q

Autogenic Succession
organisms change environment to
time scale

A

Temporal succession of species at a location driven by processes operating within community

  • Organisms Change Environment to harm/favor others
  • Time Scale – Life of Organisms
  • biotic factors
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9
Q

Allogenic Succession

A

Temporal succession of species at a location driven by external influences which alter conditions

  • Massive Disturbances, Environmental Shifts
  • Time Scale – Time scale of disturbance
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10
Q

Sere

A

A series of stages of community development in a particular area leading to a stable state, or Climax

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11
Q

final Seral Stage

may be….

A
  • Climax
  • -Final Seral Stage
  • -Endpoint of a successional sequence
  • -A Community that has reached a steady state under a particular set of environmental conditions
  • May be definitive or Tenuous
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12
Q

Seres are different for and are determined by

A

-Different for each environment
-Determined by surrounding:
Vegetation
Nutrients
Soil Characteristics
Etc.

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13
Q

Sand Dunes

A
  • Soils Unstable/Shifting
  • Low Nutrient Content
  • 1st colonizers:
  • -Stabilize soil
  • -Add Organic material
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14
Q

old fields

A

Old Fields

  • -Soils More Stable
  • -Higher Nutrients
  • quicker to colonize
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15
Q

closed community

A

Closed Community

  • Clementsian View
  • Species closely associated
  • Ecological limits of Individual Species = Ecological Limits of Community
  • Ecotones Distinct
  • -Transition between communities well defined
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16
Q

open community

A
  • Gleasonian View
  • Species distributed independently
  • No Natural Boundaries
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17
Q

Climax – Early Studies

A

Determined solely by
climate
-Similar Climaxes within the Same Regions

18
Q

Clementsian Climax

-how many climaxes

A

Identified 14 climaxes in North America
-2 grasslands, 3 scrub, and 9 forest
All others were interrupted seral stages
-Fire, animals, soils, topography
Sub-climaxes could persist unchanged for long periods
-Due to “unnatural” disruptions to seral stages

19
Q

Present Day Climax

A

Early Ideals Questioned or Dismissed for Open Community Concept
-local climaxes

Communities Vary Continuously over Gradients

20
Q

Continuum Index

A

change in community composition based on environmental gradient

21
Q

Succession begins with

A

disturbance or creation of new habitat

-Opens areas for Colonization of New Species

22
Q

succession driven by

A

Driven By Plants Differential Ability to:

  • colonize
  • compete
23
Q

Disturbances definitions

A
  • Any Process that limits plants by destroying plant biomass (Grimes 1977)
  • Any discrete, punctuated, killing, displacement, or damaging of ≥ 1 individuals that creates opportunity for new individuals (Sousa 1984)
  • Any relatively discrete event that disrupts structure & changes resources, substrate availability, or physical environment (White & Pickett 1985)
24
Q

types of disturbances

A
  • Physical Disturbance

- Biological Disturbance

25
Q

succession disturbances

A

Set Back Succession
Remove all Life from area
Eruption of Mt. St. Helens

26
Q

Old Field Succession

A

Changes Fast Initially
Slows over time
Slow Growing Plants

27
Q

Colonization occurs from:

A

areas surrounding disturbed area

areas some distance away from disturbed area

seed bank

Disturbance may leave individuals remaining alive

28
Q

Colonization Primary Force in Succession

-Succession directed by Species’ Ability to:

A

Cope with Environmental Conditions
Often Low Nutrients
Disperse into Disturbed Areas
Modify Environment

29
Q

Pioneer species

have the best combination of what

A

Species that are among the first to become established
Best combination of Coping & Dispersal
Often Determine Successive Colonizers

30
Q

best colonizers are

slower colonizers are

A

Best Colonizers often worst Competitors

  • Weeds
  • -Invade Quickly But are short lived
  • -Generally do not persist past 1 year
Slower Colonizers (grasses) Do persist
-Thrive After death of weeds
31
Q

Major determinants of organisms in seral stage

A

Life History of Organisms
Are Organisms Built for dispersal or competition?
Evolutionary History of Species
Nature of Changes

32
Q

Mechanisms of Succession

A

Pioneer Species Effect Future Colonizers

Clements – 1 Mechanism

Connell & Slayter (1977) 
Presence of one species effects the probability of establishment of a second in 3 ways:
Facilitation
Inhibition
Tolerance
33
Q

Facilitation

A

Many species may attempt to colonize newly available space.
-Only certain species will establish.
Pioneer Species modify environment so it becomes:
-Less suitable for themselves
-More suitable for species of later successional stages.
Autogenic processes inherent in driving process
-Addition of Organic Material
-Breakdown of Substrate to Soil
Key process in Primary Succession

34
Q

Tolerance

A

Initial occupants neither increase nor decrease the ability of other species to colonize
-Initial stages of colonization are not limited to pioneer species.
–Generally Better Nutrients & Soil remain
Change driven primarily by Allogenic Processes
-Early successional species do not facilitate later successional species.

35
Q

Inhibition

A

Early occupants modify the environment in ways that makes it less suitable for both early and late successional species.

  • Early arrivals inhibit colonization by later arrivals.
  • Assures late successional species dominate an area
  • They live a long time & resist damage by physical and biological factors.

Succession driven Primarily by Allogenic Processes
-Autogenic Processes present but impede change

36
Q

Founder Effect

A
  • Two Supremely Competitive Species Colonize area
  • Propogules of neither species competes with adults of other
  • The species that establishes first determines community structure & direction of succession
37
Q

animal species _____ with plants

A

-Continuation of Succession
–Woody Species Increase
1st small shrubs -> Small Trees ->Large Trees
-Animal Species Increase with Plants

38
Q

Primary Succession in Glacier Bay

A

4 Stages

  • Pioneer Stage – blue-green algal mats, lichens, liverworts, forbs, limited willows, cottonwoods, spruce, & Dryas
  • Dryas stage – Thick mat of Dryas, few willows, alders, spruce. ~ 30 years after Retreat
  • Alder Stage – Alder dominated, ~ 50 YAR
  • Spruce Climax – ~ 100 YAR
39
Q

Ecosystem Changes During Succession

-soil depth and organic content

A
  • Substantial changes in ecosystem structure during succession at Glacier Bay.
  • Total soil depth and depth of all major soil horizons show significant increase from pioneer community.
  • organic content, moisture, and N concentrations all increased.
  • Physical and biological systems are inseparable.
40
Q

Climax & Environment

rate of change and rate of adaptation

A

-Climax occurs when Community & Physical Environment reach Equilibrium

Rate of Change of Environment < Rate of adaptation of Existing Organisms

  • Climax Remains Until Disturbance Occurs
  • Subtle Changes Continue even at Climax
  • -Births, Deaths, & Growth Processes
  • -Less Dramatic than succession

ecology exam 2 and 3 (10 decks)

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