Disturbance Ecology: Complex Interactions

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Disturbance Ecology Complex Interactions

• Kyle Apigian Christa Dagley Igor Lacan
• 18 November 2003

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Disturbance Ecology Complex Interactions
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Complex Interactions

• Longleaf
  Pine
• (Pinus
  palustris)

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Complex Interactions

• Fire-dependent ecosystem
• summer lightning fires
• 2-8yr FRI
• Most species rich vascular
  plant communities found in
  the temperate zone
• Pine savannas - highest level of
  endemism in N. America
• Today only 3 of its original acreage remains

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Complex Interactions

• Contributing factors include
• naval stores
• logging
• competition
• feral hogs
• intensive forestry
• fire exclusion

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Complex Interactions

• First product
• Uses seal cracks on wooden ships, preserve ropes
  and sails.

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Complex Interactions

• Contributing factors include
• naval stores
• logging
• competition
• feral hogs
• intensive forestry
• fire exclusion

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Complex Interactions

• Competition
• loblolly and other pines
• large seeds eaten by birds, rodents and insects
• irregular seed production

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Complex Interactions

• Contributing factors include
• naval stores
• logging
• competition
• feral hogs
• 20 seedlings/ha vs. 14,826 s/ha
• intensive forestry
• fire exclusion

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Complex Interactions

• Contributing factors include
• naval stores
• logging
• competition
• feral hogs
• intensive forestry
• very poor survival
• perceived slow early growth
• fire exclusion

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Complex Interactions

• Contributing factors include
• naval stores
• logging
• competition
• feral hogs
• intensive forestry
• fire exclusion
• grass stage
• thick bark
• good self pruner

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Complex Interactions McCay (2000)

• Effects of chronic human activities on invasion
  of longleaf pine by sand pine
• Florida Panhandle
• Landscape Level aerial photography to quantify
  the extent and expansion of sand pine.
• Population Level 12 stands sampled to verify
  photo interpretation and assess successional
  trends
• To assess past vegetation patterns and land-use
  activities, qualitative data for the area was
  collected

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Complex Interactions
Total 41,900 ha
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Complex Interactions
Distribution of SP establishment in 5-yr intervals

• Noninvasive - Stands with no longleaf pine in the
  canopy.

Turpentining ceased
Fire suppression
Grazing discont.
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Complex Interactions

• Conclusions
• sand pine invasion occurred b/c of the complex
  interaction of several factors that increased the
  susceptibility of LL to enchroachment
• Turpentining
• competition
• LL crop failures
• fire suppression
• logging

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Complex Interactions Glitzenstein et. al (1995)

• Effects of fire regime and habitat on tree
  dynamics
• 8 year study
• sandhills and flatwoods sites
• Fire frequency (annual or biennial)
• Fire season (8 different times throughout
  the year)
• Limited fire temperature and intensity
  data taken
• Looked at recruitment, growth, mortality,
  change in density and
  BA, and species
  composition.

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Complex Interactions

• Results
• No systematic or predictable effects of season
  or frequency of
  burning on LL dynamics.
• Deciduous oaks were most vulnerable to burning in
  the early growing season (higher mortality,
  decline in BA and density).
• Spring/summer burns LL dominated forests
• Dormant season burns gradual decrease in LL and
  shift to oak dominated

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Complex Interactions

• Take Home Message
• Long-term persistence of LL, and perhaps other
  fire-adapted species in frequently burned
  LL-dominated communities, may be determined by
  complex interactions between habitat factors and
  fire regimes.

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Complex Interactions

• References
• Glitzenstein, J.S., W.J. Platt, and D.R. Streng.
  1995. Effects on fire regime and habitat on
  tree dynamics in N. Florida longleaf pine
  savannas. Ecological Monographs. 65(4)441-476.
  
• McCay, Deanna. 2000. Effects of chronic human
  actvities on invasion of longleaf pine forests
  by sand pine. Ecosystems. 3 283-292.
• Outcalt, Kenneth. 2002. The Longleaf pine
  ecosystem of the south. Native Plants Journal.
  1(1) 42-51.

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Southern California reef Kelp, sea urchins, and
surfperch behavioral responses of urchins and
fish after storms Galapagos Islands
Darwins finches behavioral and phenotypic
responses to drought and El Nino
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• Severe storm disturbances and reversal of
  community structure in a southern California kelp
  forest

A.W. Ebeling, D.R. Laur and R.J. Rowley. 1985.
Marine Biology 84, 287-294
From Ebling et al 1985
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From Ebling et al 1985
Post storm 1 Kelp canopy removed drift kelp
lost Urchins left crevices
to find food ate standing kelp and algal turf
Urchin population poorly
regulated reef became a barrens Post storm 2
Storm killed off exposed urchins
Kelp resettled in great abundance Same
disturbance resulted different (reverse) effects
depending on prior community structure

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From Ebling et al 1985
Surfperch feed on benthic arthropods that live in
the algal turf Loss of algal turf caused a
decline in surfperch populations
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From Stouder 1987
Storm effects were not equal across reef, some
microhabitats (reef slope, reef crest) retained
algal turf 5 surfperch species converged in
terms of microhabitat usage Diet was not
significantly affected Less aggressive,
generalist fish left early in season ?
competitive exclusion?
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From Stouder 1987
Storm effects were not equal across reef, some
microhabitats (reef slope, reef crest) retained
algal turf 5 surfperch species converged in
terms of microhabitat usage Diet was not
significantly affected Less aggressive,
generalist fish left early in season ?
competitive exclusion?
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Darwins finches effects of climactic
disturbances on population structure and natural
selection
From Grant 1986
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Rainfall on the Galapagos
From Grant et al 2000
Galapagos islands high inter-annual variability
in rainfall drought years little or no
rain El Niño years excessive rain
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Ex. 1. Geospiza conirostris large cactus finch
From Grant and Grant 1989
High intraspecific variation in beak size and
shape in this species From long and pointed to
shorter and deep. Beak shape is related to
foraging success in one of 3 foraging modes
during the dry season 1. Hammering Opuntia
(cactus) fruits ? long, pointed bills 2. Seed
cracking ? long, deep bills 3. Stripping bark (to
obtain arthropods) ? deep bills
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Ex. 1. Geospiza conirostris large cactus finch
Extreme rain followed by drought affected food
supply (cactus fruit and flowers) Birds with
long, pointed bills were at a selective
disadvantage. Birds with deep bills could
exploit other foods
From Grant and Grant 1989
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Ex. 1. Geospiza conirostris large cactus finch
Primary foraging mode
Small seeds
Large hard seeds
Ripping Opuntia cactus pads to obtain arthropods
From Grant and Grant 1989
From disruptive to directional selection
Variety of beaks favored in normal years ? large
deep bills favored after disturbance
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Ex. 2. Geospiza fortis medium ground finch -
DROUGHT
From Boag and Grant 1981
Drought of 1977 resulted in 85 decline in finch
population on Daphne Major Decline was highly
correlated with a decline in seed abundance
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Ex. 2. Geospiza fortis medium ground finch -
DROUGHT
From Boag and Grant 1981
Effects of this disturbance on population
structure were non-random large birds more
likely to survive than small birds Large, hard
seeds became proportionally more abundant during
the drought, as competition for small seeds
became intense Large birds (with large bills)
could crack the remaining hard seeds
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Ex. 2. Geospiza fortis medium ground finch -
DROUGHT
Proportional increase in fitness
Body size
Bill pointedness
From Boag and Grant 1981
The drought of 1977 resulted in phenotypic
changes to the G. fortis population
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From Grant et al 2000
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Ex. 3. Geospiza fortis and G. scandens EL NINO
From Grant et al 2000
Caterpillar abundance is significantly greater
during El Niño events
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Ex. 3. Geospiza fortis and G. scandens EL NINO
From Gibbs and Grant 1987a
Exceptional rains resulted in increases in total
seed biomass The proportion of small seeds in
the environment increased significantly
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Summary. Geospiza fortis and G. scandens
Selection during drought years is for large
birds Selection during El Niño is for smaller
birds with smaller beaks. Why? More efficient
handling of small seeds? Better competitors with
smaller finches?
From Gibbs and Grant 1987b
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Conclusions Behavioral shifts following a
disturbance event can have effects on multiple
trophic levels Individuals with phenotypic
traits far to one end of the population
distribution may be favored following a
disturbance Climactic disturbances, such as
droughts and El Nino, can exert strong selection
pressure on populations.
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References

• Boag, P. T. and P. R. Grant. 1981. Intense
  natural selection in a population of Darwins
  finches. Science 214 82-85.
• Ebeling, A. W., D. R. Laur, and R. J. Rowley.
  1985. Severe storm disturbances and reversal of
  community structure in a southern California kelp
  forest. Marine Biology 84 287-294.
• Grant, B. R. 1985. Selection in bill characters
  in a population of Darwins finches Geospiza
  conirostris on Isla Genovesa, Galapagos.
  Evolution 39(3) 523- 532.
• Grant, B. R. and P. T. Grant. 1989. Natural
  selection in a population of Darwins finches.
  American Naturalist 133(3) 377-393.
• Grant, P. R. 1986. Ecology and Evolution of
  Darwins Finches. Princeton University Press,
  Princeton, NJ.
• Grant, P.R., B. R. Grant, L. F. Keller, and K.
  Petren. 2000. Effects of El Nino events on
  Darwins finch productivity. Ecology 81(9)
  2442-2457.
• Gibbs H. L. and P. R. Grant. 1987. Ecological
  consequences of an exceptionally strong El Nino
  event on Darwins finches. Ecology 68(6)
  1735-1746.
• Gibbs H. L. and P. R. Grant. 1987b. Oscillating
  selection on Darwins finches. Nature 327
  511-513.
• Price, T. D., P. R. Grant, H. L. Gibbs, and P.
  T. Boag. 1984. Recurrent patterns of natural
  selection in a population of Darwins finches.
  Nature 309 787- 789.
• Stouder, D. J. 1987. Effects of a severe-
  weather disturbance on foraging patterns within
  a California surfperch guild. Journal of
  Experimental Biology and Ecology 114 73-84.17

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Complex Interactions Aquatic Ecosystems - General

• Pringle and Hamazaki, 1997
• Effects of Fishes on Algal Response to Storms in
  a Tropical Stream
• or
• how trophic factors interact with disturbance
  to affect community response.

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Complex Interactions Aquatic Ecosystems -
GeneralPringle and Hamazaki, 1997

• Methods
• Colonization tiles
• For algae, macroinvertebrates
• Fish exclosures (electric!) vs. controls
• Sampled tiles for algae, macroinvertebrates
• Three large storms during the experimental period
• On days 10, 26, and 39-40
• ANOVA

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Complex Interactions Aquatic Ecosystems -
GeneralPringle and Hamazaki, 1997

• Results 1 Algal Biovolume

Fig. 2
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Complex Interactions Aquatic Ecosystems -
GeneralPringle and Hamazaki, 1997

• Results 2 Algal Community Composition

Fig. 4
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Complex Interactions Aquatic Ecosystems -
GeneralPringle and Hamazaki, 1997

• Results 3 Percent Change in Ecosystem Parameters

Table 4
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Complex Interactions Aquatic Ecosystems -
GeneralPringle and Hamazaki, 1997

• Discussion
• Fish present diatoms ? cyanobacteria ?
• Storms regularly remove diatoms
• No trophic cascade
• Omnivory in fishes. Or regular storms
• Omnivorous fishes play a key role in maintaining
  stability of benthic algal communities and their
  resistance to hydrologic disturbance

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Complex Interactions Aquatic Ecosystems -
Pollutants

• Johnston and Keough, 2003
• Competition Modifies the Response of Organisms to
  Toxic Disturbance
• or
• Ascidians vs. Serpulids
• Toxic and Indirect
• Effects of Copper

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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Methods
• 2 Experiments
• Frequency and Intensity dose toxicant
• 2 doses, 2 frequencies
• Space dose toxicant remove competitors
• Sampled for density of Ascidians and Serpulids
• ANOVA

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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Results 1 Ascidians reduced

from Fig. 2
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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Results 2
• Most Serpulids increased

from Fig. 3
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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Results 3 Space

from Fig. 4
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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Results Summary

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Complex Interactions Aquatic Ecosystems -
PollutantsJohnston and Keough, 2003

• Discussion
• Frequency substitutes for intensity
• Copper effects on serpulids an integration of
• Indirect effects releases space
• Direct effects toxicity (species-specific)
• Good Competitor vs. Good Disperser tradeoff
• Episodic pollution favors

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Complex Interactions Aquatic Ecosystems More
PollutantsCourtney and Clements, 2000

• Sensitivity to acidic pH in benthic invertebrate
  assemblages with different histories of exposure
  to metals
• A microcosm experiment
• Interaction between 2 disturbance forces
  (pollutants) that are sequential in time
• Previous exposure to metals increases sensitivity
  to low pH
• A species-level response scales up to assemblage
  level

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Complex Interactions Aquatic EcosystemsReferenc
es

• Courtney, L. A., and W. H. Clements. 2000.
  Sensitivity to acidic pH in benthic invertebrate
  assemblages with different histories of exposure
  to metals. J. N. Am. Benthol. Soc. 19(1)
  112-127
• Johnston, E. L., and M. J. Keough. 2003.
  Competition modifies the response of organisms to
  toxic disturbance. Mar. Ecol. Prog. Ser. 251
  15-26
• Pringle, C. M., and T. Hamazaki. 1997. Effects
  of fishes on algal response to storms in a
  tropical stream. Ecology 78(8) 2432-2442
• Salminen, J., B. T. Anh, and C. A. M. Van Gestel.
  2001. Indirect effects of zinc on soil microbes
  via a keystone Enchytraeid species. Env.
  Toxicology and Chemistry 20(6) 1167-1174
• Morrison, H. A., D. M. Whittle, and G. D.
  Haffner. 2000. The relative importance of
  species invasions and sediment disturbance in
  regulating chemical dynamics in western Lake
  Erie. Ecological Modelling 125 279-294