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Patterns in time. Ecological succession. Frederic E. Clements 1874-1945. Henry A. Gleason 1882-1975. Plant succession is the directional development of the vegetation of a given homogeneous area over a period of time towards a single climax structure (Clements 1916).

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slide1

Patterns in time

Ecological succession

Frederic E. Clements 1874-1945

Henry A. Gleason 1882-1975

Plant succession is the directional development of the vegetation of a given homogeneous area over a period of time towards a single climax structure (Clements 1916)

Plant succession is the historically influenced random process leading to different stable states despite identical environmental conditions (Gleason 1927)

slide3

Primary Successional stages

Bare soil of rocks

Succession is not a deterministic process.

The successional sequence might end in different final stable states

Annual and biannual plants

Soils crusts, Cyanobacteria, Lichen, Mosses

Pioneer species

Shrubs, trees

In manytemperaturesuccessioalseriesforests form the climaxcommunity

Climax community

slide5

Soilcrusts

Cyanobacteria, mosses, lichen

Soilmosses and lichen

Crusts are well adapted to severe growing conditions, drought and waterloss.

Crusts generally cover all soil spaces not occupied by vascular plants, and may be 70% or more of the living cover

Cyanobacteria

Soilcrustsstabilizesoils and increasewaterretention.

slide6

Secondary succession

Secondary succession is the change in faunal or floral composition after severe disturbance

Major disturbances are

Fire

Storm

Flooding

Lava flows

Secondary succession starts mainly from seed banks.

Colonization is often of minor importance.

Seeds remain healthy for some months to more than 1000 years.

In cyclic succession (frequent fires)seed banks allow for fast recover.

slide7

Adaptive strategies

Modified from Brown, Southwood 1987

Plants, herbivorous insects

Generation time

Reproductive effort

Plants, aphids

Plants, birds, some insects

Niche breadth

Morphological diversity

Herbivorous insects

Bees, wasps

Flight ability

Diversity

Plants, insects

Woodlands

Young field

Midfield

Successional stage

Different successional stages filter for different life history strategies (habitat filtering)

slide8

The r – K – A triangle

Habitat templates (Southwood and Greenslade)

slide9

Communitypatternsduringsuccession

Annuals and biannuals

Annuals and biannuals

Shrubs

Speciesrichness

Shrubs

Abundance

Trees

Trees

Time

Time

Speciesrichness, totalabundance, and totalbiomassgenerallypeakatintermediatestages of succession.

Biomass

Time

slide10

Succession of beta diversity

Brown, Southwood 1987

slide11

Intermediate disturbance

Competitiion

New Zealand stream invertebrates (Townsend 1997)

Extinction

Immigration

Number of niches

slide12

The Markov chain approach to succession

Henry S. Horn 1941-

Abundances

Columnstochastic transition probability matrix

Stable state (eigen)vector

slide13

Bertness, Leonhard, Ecology 78: 1976-1989

Positiveinteractions

Joint defences

Habitat amelioration

Frequency of competitiveinteractions

Frequency of positiveinteraction

Increasingphysicalstress

Increasingconsumerpressure

The stress gradient hypothesispredictsincreasedproportions of positive (mutualistic) interactions in plant communitiesatintermediatelevels of stress and herbivorepressure.

slide14

3

3

3

2

2

2

1

1

1

0

0

0

-1

-1

-1

-2

-2

-2

Oulu

Vaasa

Central Finland

-3

-3

-3

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

3

3

3

2

2

2

1

1

1

0

0

0

-1

-1

-1

-2

-2

-2

Häme

Uusimaa

Turku-Pori

-3

-3

-3

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

3

3

3

2

2

2

1

1

1

0

0

0

-1

-1

-1

-2

-2

-2

Lapland

Kuopio

North Karelia

-3

-3

-3

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

3

3

2

2

1

1

0

0

-1

-1

-2

-2

Mikkeli

Kymi

-3

-3

1964

1968

1972

1976

1980

1964

1968

1972

1976

1980

Linkedpatterns in time

Population dynamics (1964 to 1983) of the red squirrel in 11 provinces of Finland (Ranta et al. 1997)

Patrick A.P. Moran (1917-1988)

The Moran effect

Regionalsychronization of localabundancesdue to correlatedenvironmentaleffects

slide15

20

30

40

50

60

70

80

90

Defoliation by gypsy moths in New England states

700000

Maine

600000

500000

Acres Defoliated

400000

300000

200000

100000

0

2500000

New Hampshire

2000000

1500000

Acres Defoliated

1000000

500000

0

140000

120000

Vermont

Lymantria dispar

100000

80000

Acres Defoliated

60000

40000

20000

0

3000000

Massachusetts

Gradation:

The massive increase in density

2500000

2000000

Acres Defoliated

1500000

1000000

500000

0

Year

Data from Williams and Liebhold (1995)

slide16

Taylor’s power law

Assume an assemblage of species, which have different mean abundances and fluctuate at random but proportional to their abundance.

Going Excel

The relationship between variance and mean follows a power function of the form

Taylor’s power law; proportional rescaling

slide17

Ecological implications

Temporal variability is a random walk in time

Abundances are not regulated

Extinctions are frequent

Temporal species turnover is high

Temporal variability is intermediate

Abundances are or are not regulated

Extinctions are less frequent

Temporal species turnover is low

Temporal variability is low

Abundances are often regulated

Extinctions are rare

Temporal species turnover is very low

slide18

Evolutionarytimescales

Nicheconservatismrefers to the tendency of closelyrelatedspecies to havesimilarnicherequirements. The requirementstranslateintosimilarecological, morphologicalorbehaviouraltraitsmediated by genomicsimilarities.

100%

Body size

Female body length

Sex dimorphism

How much variance in importantnichedimensions of Europeanplantsisexplained by taxonomcrelatedness?

Male body length

Dietaryrange

Colours

Migratorybehaviour

50%

Shadingpreference

Abundance

Moisturepreference

German rangesize

Shadingtolerance

Habitat tolerance

Moisturetolerance

Europeanrangesize

0%

Spiders

Birds

Entling et al. 2007, Gl. Ecol. Biogeogr. 16: 440-448

Prinzing et al. 2001. Proc. R. Soc. B 268: 1.

slide19

1

0.8

0.6

Fraction of

singletons

0.4

0.2

0

1

10

100

1000

10000

Number of species

1

0.8

0.6

Fraction of

abundant species

0.4

0.2

0

1

10

100

1000

10000

Number of species

Taxon species richness and local abundances

The case of Hymenoptera

Continental taxon species richness of Hymenoptera is correlated to mean local abundances

Species rich hymenopteran taxa contain more locally rare and fewer locally abundant species

5

4

3

Mean density

per species

2

1

0

1

10

100

1000

10000

Number of species

slide20

Numbers of families and species scale allometrically to floral species richness

60

  • Species richer sites contain relatively less higher taxa.
  • Species richer sites have higher species per genus (S/G) ratios
  • Species richer sites contain higher proportions of ecologically similar species(environmental filtering)

50

40

Number of genera

30

20

0.77

y = 1.78x

10

2

R

= 0.94

0

0

20

40

60

80

Number of species in a flora

35

Darwin’scompetitionhypothesis:

Closelyrelatedspeciesshould be ecologicallymoresimilar and underhigherselectionpressurethanmoredistantlyrelatedspecies

30

25

20

Number of families

15

10

0.61

y = 1.9x

5

2

R

= 0.70

0

0

20

40

60

80

Number of species in a flora

Enquist et al. 2002. Nature 419: 610-613

slide21

Earlysuccession

Regionalpool of species

Regionalpool of species

Facilitation

Regionalpool of potentialcolonizers

Environmentalfilters

Randomcolonization

Phylogeneticsegregation

Phylogeneticclumping

No phylogeneticstructure

No phylogeneticstructure

Localcolonizers

Latersuccession

Competition

Positiveinteractions

Neutralinteractions

Phylogeneticsegregation

No phylogeneticstructure

Phylogeneticclumping

Localcommunitystructure

Zaplata et al. 2013