![Page 1: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/1.jpg)
Why does succession take so long?
• Different plant species have different ecological requirements. A beech or live-oak needs shade as a seedling.
• They also need soil moisture which means the soil must have a high organic content.
• So succession is also the development of soil and colonization by soil organisms.
![Page 2: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/2.jpg)
3 models of successionConnell and Slatyer (1979)
![Page 3: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/3.jpg)
Facilitation
• Initially thought that all succession was due to facilitation.
Example of facilitation: shade provided by pines allows seedlings of broad-leaved trees to survive.
Or
Growth of a nitrogen-fixing plant on sandy (nutrient poor) soils such as alder enriches the soil sufficiently for other species to colonize.
![Page 4: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/4.jpg)
Tolerance
• All species could live at all stages of the succession, but differing dispersal abilities/adaptations ensures earliest stages occupied by pioneer-type species.
• As succession proceeds fewer and fewer of the early successional species can tolerate the new conditions and so the system matures toward D.
• Dispersal distance is therefore also a big factor to be considered.
![Page 5: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/5.jpg)
Inhibition
• Species mutually inhibit one another through competition. System can only change when an individual dies an is replaced.
• What will influence that replacement?
![Page 6: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/6.jpg)
Soil maturity and succession
• Soil accumulates organic matter as succession proceeds.
• Increased ability to hold moisture.
• Pioneer species are shaded out.
![Page 7: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/7.jpg)
The balance
• Now understood that facilitation, tolerance, and inhibition all combine to produce succession.
![Page 8: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/8.jpg)
Clements vs Gleason
• We now know that species respond individualistically to change.
• Communities are not superorganisms and will not always return to a predictable equilibrium.
![Page 9: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/9.jpg)
Colonization of new areasPrimary Succession: Colonization of new areas
![Page 10: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/10.jpg)
Colonization of a new area
• Follows succession from pioneers to competitors…..but all have to disperse there.
• Distance from source is important…can larvae survive long enough to be transported there? Can seeds be blown there? Can mammals swim there? Can birds fly there?
![Page 11: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/11.jpg)
Two ways to study succession
• Follow one location from disturbance to maturity, ex. Krakatau, Mt St Helens.
• Select similar habitats at different times since similar disturbance, ex. Glacier Bay, building riverbank
![Page 12: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/12.jpg)
• Macroalgal succession over 30 months on experimental concrete blocks.
UlvaSea lettuce
Intertidal succession
![Page 13: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/13.jpg)
• Steadily retreating glacier since 1850s.
• New land surface revealed…primary succession.
• Oldest succession where ice first retreated.
1850
1912
Primary succession in Glacier Bay, Alaska
![Page 14: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/14.jpg)
Glacier Bay Succession
• Retreating glaciers expose new land surface of till.
• Rate of retreat ca. 65 km in 200 years
• Succession follows broadly predictable path
![Page 15: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/15.jpg)
![Page 16: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/16.jpg)
Nutrient changes at
Glacier Bay• The initial soil is nutrient
poor.• Alder is an N-fixer, spruce
and hemlock are not.• “forest floor” reflects N in
leaf and wood litter.• Why is there a peak in
forest floor N at the transition to spruce-hemlock.
• Why does soil N decline in the spruce-hemlock zone?
![Page 17: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/17.jpg)
![Page 18: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/18.jpg)
AT least that has been the accepted story..BUT!
• Fastie (1995, Ecology) shows that alder may actually slow the succession through competition.
• The succession to Sitka Spruce was much faster in the sites deglaciated in the 1780s-1840s than the later sites.
• And hemlock has not begun to grow at any site that initiated after 1840.
![Page 19: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/19.jpg)
![Page 20: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/20.jpg)
Simulation showing nitrogen inputs during 2ndry succession
Importance of alder (ALRU) as a nitrogen fixer and Ceanothus (CEVE), early in succession.
![Page 21: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/21.jpg)
Nitrogen sources
![Page 22: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/22.jpg)
Rotmoos Glacier, Italian alps 1895
![Page 23: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/23.jpg)
Rotmoos Glacier, Italian alps 1999
![Page 24: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/24.jpg)
Rotmoos Glacier, Italian alps
• 1895 glacial tongue evident in valley
• 1999 2km of retreat evident
• Following is work by Kauffman, Ecology (2001)
![Page 25: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/25.jpg)
First 50 yrs
• Sparse vegetation means little local productivity.
• Surprisingly, insects are primarily predators relying on allochthonous (derived from elsewhere) sources of prey
5 yrs: Harvestman- a glacial specialist Predator.
10 yrs: 4 spp. Of ground beetle, occupying separate niches.
20 yrs: assorted spidersAbundant.
30 yr Centipedes, under rocks50 yrs: herbivorous beetles as vegetation density increases.
![Page 26: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/26.jpg)
50-150 yrs first
appearances
• As vegetation increases in density a more normal insect spectrum is represented with food chains supported by herbivores. Detrital cycle also evident. System now autochthonous (productivity is local).
70 yr: millipedes are important decomposers.
100 yrs: 1 sp. Of ant occupies sunniest locations
140 yrs: Densest Vegetation supportsgrasshoppers
![Page 27: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/27.jpg)
Effect of succession on adjacent waters
• Shading of margins• As succession increases soil organic content will
also increase dissolved organic carbon (DOC), e.g. humic acids and tannins.
• Leaching into waterways these chemicals color the water and reduce transparency.
![Page 28: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/28.jpg)
![Page 29: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/29.jpg)
Dissolved Organic Carbon, e.g humic acids influences aquatic
foodchainsMacroZooplanktonSpp.#
2
3-4
5
DOC
Low
Moderate
High
![Page 30: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/30.jpg)
Mt St. Helens example of interference
• Lupins are N fixers and were colonists after the Mt St. Helens eruption.
• Lupin expansion rapid at first but slowed after a few years.
Fagan & Bishop(American Naturalist 2000)
![Page 31: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/31.jpg)
• At expansion edge Lupin expansion limited by herbivory.
• In center of lupin range herbivory limited by predation.
Interactive effects of
herbivory and predation
![Page 32: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/32.jpg)
This river is building a spit
• As the spit grows the youngest vegetation will be on the tip.
• Often a clear succession, both in terms of age and species composition, is evident.
![Page 33: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/33.jpg)
Succession in streams &rivers
• Note the change in size and species composition beside the channel
![Page 34: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/34.jpg)
Can we make predictions about the colonization process?
• Here is an island.
• Most plants are going to arrive either by wind, sea, or bird/bat.
![Page 35: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/35.jpg)
Krakatau case study
• Krakatau is an island group in Indonesia.
• A volcanic eruption sterilized the islands in 1883.
![Page 36: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/36.jpg)
Krakatau: The best example of primary succession
• Aug 27th 1883 Volcanic explosion sterilized islands
• 2000 times the power of the bomb dropped on Hiroshima.
• Generated tsunami that killed 36,000 people• 100 m thickness of new ash coated the
islands…new land surface. A natural laboratory.
• Colonization of plants and animals documented since 1884.
Krakatau is west of Java
![Page 37: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/37.jpg)
Immediately after the eruption• 1884: no plant life found, some blue-green algae growing
on ash.
• 1896: there were some coastal shrubs, scattered grasses and shrubs in the interior.
• 1908: Interior a “parkland” of grasses and clumps of trees.
![Page 38: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/38.jpg)
The succession continues
• 1928-1932: forests close over the grassland.• 1979-1992: forests changing in species composition.
Earliest trees now 60-80 years old.
![Page 39: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/39.jpg)
Increase in species diversity• Plant species
continue to colonize the islands.
• New plants provide new opportunities for animals.
• Animals cannot colonize until foodplant is present.
![Page 40: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/40.jpg)
Pattern evident in dispersal
mechanism of arrivals
• At first wind and sea dispersed species.
• Later trees dominated by bird and bat dispersed species.
• Wind dispersal still brings orchids and ferns.
![Page 41: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/41.jpg)
Large pigeons and bats regularly move between islands and
mainland
![Page 42: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/42.jpg)
Development of structure
• As succession proceeds the physical structure of the vegetation becomes more complex, offering more niches. Trunk-cavities, vines, larger limbs.
• How would this affect recruitment?
![Page 43: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/43.jpg)
Why structure matters
• The more layers in the canopy the higher the animal diversity.Offer different feeding opportunities.
• Trunk-cavities provide nest sites for birds and insects.
• Vines provide food, cover and nest sites.• Dead wood for decomposers • Larger limbs better attachment sites for
epiphytes.
![Page 44: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/44.jpg)
Biotic and abiotic influences
• Nitrogen likely to be limiting nutrient early in succession….why?
![Page 45: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/45.jpg)
Source of recovery will be different in
primary and secondary succession
![Page 46: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/46.jpg)
How habitat quality
influences succession
• Walker and Chapin’s model considers the importance of major ecological factors in succession in terms of severe and favorable landscapes.
![Page 47: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/47.jpg)
Walker and Chapin Cont.
• Note how differently facilitation and competition influence succession.
![Page 48: Why does succession take so long? Different plant species have different ecological requirements. A beech or live- oak needs shade as a seedling. They](https://reader036.vdocuments.us/reader036/viewer/2022081520/5697bf701a28abf838c7da69/html5/thumbnails/48.jpg)