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Impacts of Invasions

Impacts of Invasions. Measuring impact is complex What should be measured and how?. For individual plant, individual species, or multiple species?. Over what time frame?. Lack of comprehensive data. Impacts of Invasions. Ecology Species replacement Ecosystem functions

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Impacts of Invasions

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  1. Impacts of Invasions • Measuring impact is complex • What should be measured and how? • For individual plant, individual species, or multiple species? • Over what time frame? • Lack of comprehensive data

  2. Impacts of Invasions • Ecology • Species replacement • Ecosystem functions • Threatened & endangered species • Economic • Total environmental damage estimates • Social • Water quantity and quality • Human health

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

  4. Ecological Impacts • Types of impacts (Parker et al. 1999) • Impacts on ecosystem properties • Impacts on community structure • Impacts on individual species

  5. Ecological Impacts • Impacts on ecosystem properties 1. Disturbance regimes

  6. D’Antonio in Mooney & Hobbs (2002)

  7. Ecological Impacts • Impacts on ecosystem properties 2. Resource dynamics

  8. Ehrenfeld (2003) Ecosystems 6: 503-523

  9. Ecological Impacts: Nitrogen Question: How is N cycling affected by exotic grass invasion? Method: Examined rates of N mineralization & nitrification, and characterized soil microbial communities • Hawkes et al. (2005) Ecology Letters 8:976-985

  10. Hawkes et al. (2005) Ecology Letters 8:976-985

  11. Ehrenfeld (2003) Ecosystems 6: 503-523

  12. Ecological Impacts: Carbon • Woody plant invasion into grasslands is thought to increase amount of C stored

  13. Ecological Impacts: Carbon Question: Does woody plant invasion increase C sequestration? Method: Examined 6 sites along precipitation gradient • Jackson et al. (2002) Nature 418:623-626

  14. Jackson et al. (2002) Nature 418:623-626

  15. Jackson et al. (2002) Nature 418:623-626

  16. Ehrenfeld (2003) Ecosystems 6: 503-523

  17. Tamarix ramosissima Ladenburger et al. (2005) J. of Arid Env 65: 111-128.

  18. Ecological Impacts: Water Kulmatiski et al. (2006) Plant & Soil 288: 271-284 Question: Does plant invasion shift timing of water use? Method: Used stable isotope ratios in soil and plant tissue

  19. Ecological Impacts Ecosystem engineers: species able to physically alter habitats (Crooks 2002) • Alter ecosystem physical processes (sedimentation, water availability, N cycling) • Change habitat structure (more or less complexity) • Effects cascade through community

  20. Crooks (2002) OIKOS 97: 153-166

  21. Question: What is the long-term impact of C. pubescence invasion on Galapagos vegetation? Methods: Monitoring permanent plots over 7 years Jager et al (2009) J of Ecology 97:1252-1263 Ecosystem Impacts: Transformers

  22. Jager et al (2009) J of Ecology 97:1252-1263

  23. Jager et al (2009) J of Ecology 97:1252-1263

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