1 / 54

Disturbance Ecology: Complex Interactions

Disturbance Ecology: Complex Interactions. Kyle Apigian Christa Dagley Igor Lacan 18 November 2003. Disturbance Ecology: Complex Interactions. Complex Interactions. Longleaf Pine ( Pinus palustris ). Complex Interactions. Fire-dependent ecosystem

ciqala
Download Presentation

Disturbance Ecology: Complex Interactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Disturbance Ecology: Complex Interactions Kyle Apigian Christa Dagley Igor Lacan 18 November 2003

  2. Disturbance Ecology: Complex Interactions

  3. Complex Interactions • Longleaf Pine • (Pinus palustris)

  4. 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

  5. Complex Interactions • Contributing factors include: • naval stores • logging • competition • feral hogs • intensive forestry • fire exclusion

  6. Complex Interactions • First product • Uses: seal cracks on wooden ships, preserve ropes and sails.

  7. Complex Interactions • Contributing factors include: • naval stores • logging • competition • feral hogs • intensive forestry • fire exclusion

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

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

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

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

  12. 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

  13. Complex Interactions Total = 41,900 ha

  14. Complex Interactions Distribution of SP establishment in 5-yr intervals • Noninvasive - Stands with no longleaf pine in the canopy. Fire suppression Turpentining ceased Grazing discont.

  15. 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

  16. 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.

  17. 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

  18. 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”.

  19. 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.

  20. Southern California reef – Kelp, sea urchins, and surfperch behavioral responses of urchins and fish after storms Galapagos Islands – Darwin’s finches behavioral and phenotypic responses to drought and El Nino

  21. A.W. Ebeling, D.R. Laur and R.J. Rowley. 1985. Marine Biology 84, 287-294 Severe storm disturbances and reversal of community structure in a southern California kelp forest From Ebling et al 1985

  22. 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

  23. 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

  24. 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?

  25. 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?

  26. Darwin’s finches: effects of climactic disturbances on population structure and natural selection From Grant 1986

  27. 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

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. From Grant et al 2000

  35. Ex. 3. Geospiza fortis and G. scandens – EL NINO From Grant et al 2000 Caterpillar abundance is significantly greater during El Niño events

  36. 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

  37. 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

  38. 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.

  39. References • Boag, P. T. and P. R. Grant. 1981. Intense natural selection in a population of Darwin’s 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 Darwin’s 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 Darwin’s finches. American Naturalist 133(3): 377-393. • Grant, P. R. 1986. Ecology and Evolution of Darwin’s 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 Darwin’s 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 Darwin’s finches. Ecology 68(6): 1735-1746. • Gibbs H. L. and P. R. Grant. 1987b. Oscillating selection on Darwin’s 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 Darwin’s 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

  40. 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.”

  41. 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

  42. Complex Interactions: Aquatic Ecosystems - GeneralPringle and Hamazaki, 1997 Results 1: Algal Biovolume “Fig. 2”

  43. Complex Interactions: Aquatic Ecosystems - GeneralPringle and Hamazaki, 1997 Results 2: Algal Community Composition “Fig. 4”

  44. Complex Interactions: Aquatic Ecosystems - GeneralPringle and Hamazaki, 1997 Results 3: Percent Change in Ecosystem Parameters “Table 4”

  45. 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”

  46. 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

  47. 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

  48. Complex Interactions: Aquatic Ecosystems - PollutantsJohnston and Keough, 2003 Results 1: Ascidians reduced from “Fig. 2”

  49. Complex Interactions: Aquatic Ecosystems - PollutantsJohnston and Keough, 2003 Results 2: Most Serpulids increased from “Fig. 3”

  50. Complex Interactions: Aquatic Ecosystems - PollutantsJohnston and Keough, 2003 Results 3: Space from “Fig. 4”

More Related