Bio 2129 - Ecology
predation and hervivore NOT IN DEAIL, no time.
Bio 2129 - Ecology
Disturbance and Succession Jeremy Kerr Gendron 373 [email protected] http://137.122.14.197/bio2129
Community ecology: Succession • Disturbances can lead to enormous spatial heterogeneity • But, what happens to an ecosystem following disturbance?
-Disturbances can change charac of ecossytems. -Disturbances vary in intensity (hardcore:fires... medium: winds) -Some consequences, habitats are set back to 0... they can sterelize the soils (kill all trees..) -What happesn after the disturbances take place? -Set the system to 0, sometimes take the ecosys. back a lil bit... -Sometimes theres a process of SUCESSION.
Landsat 5 (bands 3,4,5), 1999 Lake Nipigon
-Clements, old fashion, eqwualibrium view, results in a climax organismal community -Gleasons: outcome is change. Dynamic. species are individualistic.
Community ecology: Succession • In the early 20th century, ecologists were divided into two groups, led by Gleason or Clements. • Clements’ advocated the superorganism perspective, while Gleason’s view was that species are individualistic.
Page 1 1
Community ecology: Succession • Clements also suggested that communities were always developing toward a climax equilibrium. – but the “equilibrium” state depends on climate, edaphics, and takes so long to reach it may never be attained!
Community ecology: Succession • So, what happens following disturbance? – it depends on the ecosystem… Tropical forest fire
Prairie fire
Boreal forest fire
Community ecology: Succession – …and it depends on disturbance frequency… Madagascar’s degraded grasslands
Red and yellow patches are recent fires
Page 2 2
Prairies • An ecosystem that is maintained by frequent disturbance
Gallery forest
Fires • Burns every year • Fire every 10 years
Grazing
Page 3 3
Management plan for the Konza Prairie, Kansas
What if you suppress disturbances?
Trees and houses
-disturbances that are frequently that will tend to reduce diverasity. Another way to reduce diversity is to increase intensity of disturbances. -Another way, is too have very low intensityes or frequency of disturbance.
Community ecology: Succession
-system that does not have disturbance at all, u end up w competitive exclusion. They can drive species to local extinction. This process of competitive exclusion can alsp act to reduce diversity
• In theory, species richness should reach a maximum at intermediate frequencies and intensities of disturbance: the Intermediate Disturbance Hypothesis.
-
Molles 1999
Page 4 4
graphs suggest that it isnt necesarily universally true... (hyphothesis)... it might be a way to think about the systems.
Community ecology: Succession • Does disturbance frequency/intensity explain species richness in communities? – Mackey and Currie 2000
Community ecology: Succession • However, “at the limits”, disturbance (or lack thereof) can obviously affect species richness:
High intensity/high frequency disturbances
Coast redwood forest
Community ecology: Succession • A little more about succession: – two main flavours: • primary succession: the chronological change of a biotic community in a newly established area • secondary succession: chronological change of a biotic community following disturbance.
– but the temporal changes of biotic communities is still likely to depend on what is available to colonize a newly available/recently disturbed habitat.
Page 5 5
Mount St. Helen’s Before eruption
After eruption
Succession at Clearwater creek Before Mt.St.Helens eruption
1980 – after Mt.St.Helens eruption
Succession around Clearwater 1982
Page 6 6
Succession at Clearwater 1983
Succession at Clearwater 1984
Succession at Clearwater
1987
Page 7 7
-Ex: disturbance kills a couple of big trees. Now you got a light cap. This is the time where scondaty succession can begin. The species which has the greastest facility for conolizing, dispersing, will live here (ex: weeds). -
Community ecology: Succession • Early successional species are strong dispersers/competitors for nutrients – allocate resources to roots – function for climax species: enrich soil with N
• Later successional species are less good at dispersal but increasingly good competitors for light – allocate resources to shoots – function:
Early succession: low nutrients, lots of light
Late succession: more nutrients, less light
Trade off between competitive ability and colonization ability. Theoretica
Dominance fo each species with respect to time. Theoretical
Community ecology: Succession
In this oeak savannah ecossytem , easliest sucessional species are best dispersers. Limiting resource=nutrients, not light (light comptition usually prevented by fire or frazing) Note: upper left and bottom right graphs have similar things and the scales on their axis are inverted.
Tradeoff between competitive ability and colonization aility. Theoretical
Dominance ofe ach species with respect to time. Observed
Tilman 1993
Andropogon=best nutrient competitior, slowes colonizer. Agrotis=-best colonizer, weakest nutrient comeptitor.
-A species that comes later on is a better competitor for the limiting nutrinent. They take a long time to invade tho.
Community ecology: Succession
Species A has a really slow r start value for nutrients, but a very high r star value for light. What this means is when this speceis arrive to a place that is newley formed (arrived from a destructive location).. this species need to be abl to tolerate low nutrient aviability. These species that can tolerate nutrients at this concentration, then they can initiate the succession process. This is an early suceccional species, usually have rapid generations . what this means is that you got a large ppl that grows fast (plats). As they die, they add nutrients to the soil. This first succession is charaterized of them diying and adding nutrients to the soil. Now, since nutrient aviability is higher, then a new specie can come. -This new specie can push specie A to extinction... since now they are competing for light. -Nutrients supply rates are going up and up, so nutrient aviability is nto an issue anymore. However, light avilibiliy is becoming an issue. -You can graph this in theoretical terms.. where both expecies can coexist in time.. -
Page 8 8
Glacier Bay: a different example of succession
Glacier Bay
water
Glacial retreat shown from 1929 to 1963 (probably due to climate change)
Succession: After glacial retreat
Page 9 9
Forest soil + mineral soil
– organic carbon ↑ – nitrogen ↑ – pH ↓
Mineral soil
6
Organic carbon
• Soil changes
4 2 0 0
100
200
Total nitrogen 2 (gm /m )
Years since glacial retreat 300 150 0 0
100
200
Years since glacial retreat
pH variation in the soil at Glacier Bay 9 Alders
8
It would be difficult for an early successional species to invade a late successional area in Glacier Bay due to increasingly acid soils
Soil horizon from 0 to 2 inches Forest floor
7 pH 6 5 4 0
100
200
Years since glacial retreat
Page 10 10
Bio 2129 - Ecology
Disturbance and Succession Jeremy Kerr Gendron 373 [email protected] http://137.122.14.197/bio2129
Community ecology: Succession • Disturbances can lead to enormous spatial heterogeneity • But, what happens to an ecosystem following disturbance?
-Disturbances can change charac of ecossytems. -Disturbances vary in intensity (hardcore:fires... medium: winds) -Some consequences, habitats are set back to 0... they can sterelize the soils (kill all trees..) -What happesn after the disturbances take place? -Set the system to 0, sometimes take the ecosys. back a lil bit... -Sometimes theres a process of SUCESSION.
Landsat 5 (bands 3,4,5), 1999 Lake Nipigon
-Clements, old fashion, eqwualibrium view, results in a climax organismal community -Gleasons: outcome is change. Dynamic. species are individualistic.
Community ecology: Succession • In the early 20th century, ecologists were divided into two groups, led by Gleason or Clements. • Clements’ advocated the superorganism perspective, while Gleason’s view was that species are individualistic.
Page 1 1
Community ecology: Succession • Clements also suggested that communities were always developing toward a climax equilibrium. – but the “equilibrium” state depends on climate, edaphics, and takes so long to reach it may never be attained!
Community ecology: Succession • So, what happens following disturbance? – it depends on the ecosystem… Tropical forest fire
Prairie fire
Boreal forest fire
Community ecology: Succession – …and it depends on disturbance frequency… Madagascar’s degraded grasslands
Red and yellow patches are recent fires
Page 2 2
Prairies • An ecosystem that is maintained by frequent disturbance
Gallery forest
Fires • Burns every year • Fire every 10 years
Grazing
Page 3 3
Management plan for the Konza Prairie, Kansas
What if you suppress disturbances?
Trees and houses
-disturbances that are frequently that will tend to reduce diverasity. Another way to reduce diversity is to increase intensity of disturbances. -Another way, is too have very low intensityes or frequency of disturbance.
Community ecology: Succession
-system that does not have disturbance at all, u end up w competitive exclusion. They can drive species to local extinction. This process of competitive exclusion can alsp act to reduce diversity
• In theory, species richness should reach a maximum at intermediate frequencies and intensities of disturbance: the Intermediate Disturbance Hypothesis.
-
Molles 1999
Page 4 4
graphs suggest that it isnt necesarily universally true... (hyphothesis)... it might be a way to think about the systems.
Community ecology: Succession • Does disturbance frequency/intensity explain species richness in communities? – Mackey and Currie 2000
Community ecology: Succession • However, “at the limits”, disturbance (or lack thereof) can obviously affect species richness:
High intensity/high frequency disturbances
Coast redwood forest
Community ecology: Succession • A little more about succession: – two main flavours: • primary succession: the chronological change of a biotic community in a newly established area • secondary succession: chronological change of a biotic community following disturbance.
– but the temporal changes of biotic communities is still likely to depend on what is available to colonize a newly available/recently disturbed habitat.
Page 5 5
Mount St. Helen’s Before eruption
After eruption
Succession at Clearwater creek Before Mt.St.Helens eruption
1980 – after Mt.St.Helens eruption
Succession around Clearwater 1982
Page 6 6
Succession at Clearwater 1983
Succession at Clearwater 1984
Succession at Clearwater
1987
Page 7 7
-Ex: disturbance kills a couple of big trees. Now you got a light cap. This is the time where scondaty succession can begin. The species which has the greastest facility for conolizing, dispersing, will live here (ex: weeds). -
Community ecology: Succession • Early successional species are strong dispersers/competitors for nutrients – allocate resources to roots – function for climax species: enrich soil with N
• Later successional species are less good at dispersal but increasingly good competitors for light – allocate resources to shoots – function:
Early succession: low nutrients, lots of light
Late succession: more nutrients, less light
Trade off between competitive ability and colonization ability. Theoretica
Dominance fo each species with respect to time. Theoretical
Community ecology: Succession
In this oeak savannah ecossytem , easliest sucessional species are best dispersers. Limiting resource=nutrients, not light (light comptition usually prevented by fire or frazing) Note: upper left and bottom right graphs have similar things and the scales on their axis are inverted.
Tradeoff between competitive ability and colonization aility. Theoretical
Dominance ofe ach species with respect to time. Observed
Tilman 1993
Andropogon=best nutrient competitior, slowes colonizer. Agrotis=-best colonizer, weakest nutrient comeptitor.
-A species that comes later on is a better competitor for the limiting nutrinent. They take a long time to invade tho.
Community ecology: Succession
Species A has a really slow r start value for nutrients, but a very high r star value for light. What this means is when this speceis arrive to a place that is newley formed (arrived from a destructive location).. this species need to be abl to tolerate low nutrient aviability. These species that can tolerate nutrients at this concentration, then they can initiate the succession process. This is an early suceccional species, usually have rapid generations . what this means is that you got a large ppl that grows fast (plats). As they die, they add nutrients to the soil. This first succession is charaterized of them diying and adding nutrients to the soil. Now, since nutrient aviability is higher, then a new specie can come. -This new specie can push specie A to extinction... since now they are competing for light. -Nutrients supply rates are going up and up, so nutrient aviability is nto an issue anymore. However, light avilibiliy is becoming an issue. -You can graph this in theoretical terms.. where both expecies can coexist in time.. -
Page 8 8
Glacier Bay: a different example of succession
Glacier Bay
water
Glacial retreat shown from 1929 to 1963 (probably due to climate change)
Succession: After glacial retreat
Page 9 9
Forest soil + mineral soil
– organic carbon ↑ – nitrogen ↑ – pH ↓
Mineral soil
6
Organic carbon
• Soil changes
4 2 0 0
100
200
Total nitrogen 2 (gm /m )
Years since glacial retreat 300 150 0 0
100
200
Years since glacial retreat
pH variation in the soil at Glacier Bay 9 Alders
8
It would be difficult for an early successional species to invade a late successional area in Glacier Bay due to increasingly acid soils
Soil horizon from 0 to 2 inches Forest floor
7 pH 6 5 4 0
100
200
Years since glacial retreat
Page 10 10
