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Understanding Ecological Impacts of Invasive Species and Measurement Challenges

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lanza
74 diapositives · 891 Views · Aug 28, 2014

The measurement of ecological impacts caused by invasive species is a complex endeavor involving various factors. Observations highlight the need to determine what criteria should be measured—whether for individual plants, species, or ecosystems, and over what time frames. Invasive species like Helianthus tuberosus and Delairea odorata disrupt community dynamics, nutrient and water availability, and primary productivity, resulting in decreased species richness both for natives and non-natives. This article delves into the nuances of measuring these ecological impacts within conceptual frameworks established in prior research.

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  1. Impacts

  2. Impacts • Some observations: • Measuring impact is complex • What should be measured and how?

  3. Impacts • Some observations: • Measuring impact is complex • What should be measured and how? • For individual plant, individual species, or multiple species?

  4. Impacts • Some observations: • Measuring impact is complex • What should be measured and how? • For individual plant, individual species, or multiple species? • Over what time frame?

  5. Impacts • Some observations: • Measuring impact is complex • Lack of comprehensive data

  6. Impacts • Ecological • Conceptual model: From Walker & Smith in Lukens & Thieret (1997) • Invasive species affect different community & ecosystem processes

  7. Impacts • Ecological • Conceptual model: From Walker & Smith in Lukens & Thieret (1997) • Invasive species affect: • Nutrient & water availability

  8. Impacts • Ecological • Conceptual model: From Walker & Smith in Lukens & Thieret (1997) • Invasive species affect: • Nutrient & water availability • Primary productivity

  9. Impacts • Ecological • Conceptual model: From Walker & Smith in Lukens & Thieret (1997) • Invasive species affect: • Nutrient & water availability • Primary productivity • Disturbance regimes

  10. Impacts • Ecological • Conceptual model: From Walker & Smith in Lukens & Thieret (1997) • Invasive species affect: • Nutrient & water availability • Primary productivity • Disturbance regimes • Community dynamics

  11. Impacts • Ecological • i) Species replacement • Direct competition From Sherer-Lorenzen in Mooney & Hobbs (2000) • Moist, nutrient rich, disturbed sites in central Europe

  12. Impacts • Ecological Urtica (native) Helianthus (invasive) • i) Species replacement • Direct competition From Sherer-Lorenzen in Mooney & Hobbs (2000) • Moist, nutrient rich, disturbed sites in central Europe • Typically dominated by native herbUrtica dioica (stinging nettle) • Helianthus tuberosus(Jerusalem artichoke) invading

  13. Impacts • Ecological Urtica (native) Helianthus (invasive) • i) Species replacement • Direct competition From Sherer-Lorenzen in Mooney & Hobbs (2000) • Moist, nutrient rich, disturbed sites in central Europe • Typically dominated by native herb Urtica dioica (stinging nettle) • Helianthus tuberosus (Jerusalem artichoke) invading • Helianthus undermines and outshades Urtica, displacing it

  14. Impacts • Ecological • i) Species replacement • Direct competition • Large scale species displacements From Alvarez & Cushman (2002) Ecological Applications 12:1434-1444 • 3 coastal habitats in SF Bay Area • Invasive = Delairea odorata (Cape ivy) evergreen vine native to South Africa

  15. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Decreases species richness for natives (36%)

  16. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Decreases species richness for natives & non-natives (37%)

  17. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Decreases species richness for natives & non-natives and species diversity (31%)

  18. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) Cape ivy invading coastal habitats • Fewer native & non-native species • Decreases occur across all habitat types

  19. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Fewer native & non-native species across all habitats and for all plant life forms

  20. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Fewer native & non-native species • Experimentally removed Cape ivy: • Control = no removal • Disturbance = insert pitchfork into soil to simulate soil disturbance that accompanies plant removal • Reduction = hand weeded Cape ivy

  21. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Fewer native & non-native species • Experimentally removed Cape ivy: • Natives richness ↑ (10%)

  22. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) Cape ivy invading coastal habitats • Fewer native & non-native species • Experimentally removed Cape ivy: • Natives richness ↑ (10%) • Non-natives richness ↑ (43%)

  23. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Fewer native & non-native species • Experimentally removed Cape ivy: • Natives richness ↑ (10%) • Non-natives richness ↑ (43%) • Diversity ↑ (32%)

  24. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements From Alvarez & Cushman (2002) • Cape ivy invading coastal habitats • Fewer native & non-native species • Experimentally removed Cape ivy: • Other species recover, • especially forbs (other life forms NS)

  25. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors • From D’Antonio et al. (2000) Austral Ecology 25: 507-522 • Series of 14 study sites (#’s) from eastern coastal lowlands to seasonal submontane zone on Big Island, Hawaii

  26. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors • From D’Antonio et al. (2000) • Series of 14 study sites (#’s) from eastern coastal lowlands to seasonal submontane zone on Big Island, Hawaii • Lowlands: warm tropical zone with 1500-2000 mm yr-1, but dry summers; elevation from sea level to 400 m • Submontane: several °C cooler, but similar amount and seasonality of precipitation; 400 – 1200 m elevation

  27. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors • From D’Antonio et al. (2000) • Series of 14 study sites (#’s) from eastern coastal lowlands to seasonal submontane zone on Big Island, Hawaii • Lowlands: warm tropical zone with 1500-2000 mm yr-1, but dry summers; elevation from sea level to 400 m • Submontane: several °C cooler, but similar amount and seasonality of precipitation; 400 – 1200 m elevation • In both zones, fires occur; most ignited by lava or by humans • Do fires consistently favor invasives across this elevational gradient?

  28. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Measured cover of native species

  29. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Measured cover of native and exotic species

  30. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Measured cover of native and exotic species in adjacent unburned

  31. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Measured cover of native and exotic speciesin adjacent unburned and burned sites along gradient

  32. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Measured cover of native and exotic speciesin adjacent unburned and burned sites along gradient Individual sites

  33. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • For seasonal submontane: • For 26 of 35 (74%) occurrences, native had ↓ cover in burned areas Individual sites

  34. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • For seasonal submontane: • For 26 of 35 (74%) occurrences, native had ↓ cover in burned areas • For 28 of 41 (68%) occurrences, exotics had ↑ cover Individual sites

  35. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Submontane: Many natives ↓ & many exotics ↑ with fire Individual sites

  36. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Submontane: Many natives ↓ & many exotics ↑ with fire • For coastal lowlands: • 14 of 26 (54%) natives ↓ • 6 of 29 (29%) of exotics ↑ Individual sites

  37. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Submontane: Many natives ↓ & many exotics ↑ with fire • Lowlands: Fewer natives ↓ & fewer exotics ↑ with fire Individual sites

  38. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Yes, but not uniformly Individual sites

  39. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Yes, but not uniformly • Not due to differences in rainfall amount or seasonality Individual sites

  40. Impacts • Ecological • i) Species replacement • Direct competition • Large scalespecies displacements • Interacting factors From D’Antonio et al. (2000) • Do fires favor invasives across elevational gradient? • Yes, but not uniformly • Not due to differences in rainfall amount or seasonality • Appears to be due to differences in native species composition: some of the species in coastal lowlands appear to be fire tolerant Individual sites

  41. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes

  42. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  43. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  44. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  45. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  46. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  47. Impacts • Ecological • ii) Ecosystem functions • Overview • From Walker & Smith in Lukens & Thieret (1997) • Summarized: Typical effects of invasive on specific processes • And how this change on a specific process then feeds back and affects community function or structure

  48. Impacts • Ecological • ii) Ecosystem functions • Overview • Specific example: Ecosystem C storage • From Jackson et al. (2002) Nature 418:623-626 • Woody plant invasion into grasslands thought to increase amount of C stored • If so, then woody plant invasions are good for C sequestration

  49. Impacts • Ecological • ii) Ecosystem functions • Overview • Specific example: Ecosystem C storage • From Jackson et al. (2002) • Does woody plant invasion increase C sequestration? • Examined 6 sites along precipitation gradient (200 – 1100 mm)

  50. Impacts • Ecological • ii) Ecosystem functions • Overview • Specific example: Ecosystem C storage • From Jackson et al. (2002) • Does woody plant invasion increase C sequestration? • Examined 6 sites along precipitation gradient (200 – 1100 mm) that had similar age of woody plant invasion