Invasive Species Impacts

Transcription

1 Invasive Species Impacts

2 Quiz: Gallardo et al., The meta-analysis suggests a negative impact with the introduction of primary producers. Why is this result unexpected? Give one possible explanation for this result.

3 Vocab: Gallardo et al., 2016 Mesocosm medium sized recreation of environment Macrophyte aquatic plant (submerged, floating or growing from bottom to surface) Bioturbation sediment disturbance by organism Phytoplankton vs. zooplankton plant vs. animal microorganisms (floating) Benthic invertebrate bottom of water body Facultative vs. obligate herbivore optional vs. compulsory food choice (plant eaters)

4 Competition Invasive species impacts Community changes (biotic effects) Direct predation Ecosystem functioning (abiotic effects) Importance of impact is in the eye of the beholder

5 Plant competition experiments

6 Invasive plants are good competitors Based on a meta-analysis of plant competition experiments: Competition from native plants reduces invasive plant biomass by ~18% Competition from invasive plants reduces native plant biomass by ~47% Vila & Weiner, 2004

7 Invasive plants are good competitors Competition also affects reproduction First year With competition Without competition Inflorescence Lockwood, 2007

8 Invasive plant impacts on biodiversity Vila et al., 2011

9 Invasive Species as Competitors Fire ants compete for food with all native ants Reduced numbers of native ants and local extinction of several species (reduced species richness) Mack et al., 2000

10 Invasive Species as Competitors Extinction debt in native plant communities caused by habitat and connectivity losses from invasive plants Gilbert & Levine, 2013

11 Economic consequences invasive plants $35 Billion annually associated with invasive plant damage & control (mostly herbicides) Pimentel et al., 2005

12 Community change: biotic homogenization Regional loss of diversity, even though local diversity is maintained Olden, 2006

13 Community change: indirect effects Proportion of seeds remaining Ants No ants Field mouse foraging declines when fire ants are present

14 Community change: indirect effects - Earthworms may increase N deposition (break down litter faster) increasing resources - Burrowing may disrupt soil mycorrhizae (symbiots of native plants) Nuzzo et al., 2009

15 Community change: indirect effects Nuzzo et al., 2009

16 Invasive Species as Predators Towns et al., 2006

17 Invasive Species as Predators Wiles et al., 2003

18 Invasive Species as Predators At least 1 billion birds (best guess 2.4 billion) At least 5 billion mammals (best guess 12.3 billion) Loss et al., 2013 Nature Communications

19 Economic consequences $45 Billion for vertebrates Pimentel et al., 2005

20 Ecosystem function (abiotic effects) Invaded Un-invaded Mack et al., 2000 after Vitousek & Walker, 1989

21 Ecosystem function (abiotic effects) Zavaleta, 2000

22 Ecosystem function (abiotic effects) Buffelgrass (Pennisetum ciliare) Cogongrass (Imperata cylindrica) D Antonio & Vitousek, 1992

23 Invasive grass-fire cycle

24 Invasive Plants as Ecosystem Engineers Lambrinos & Bando, 2008

25 Invasive species impacts on ecosystem function Vila et al., 2011

26 Sogge et al., 2005 Positive impacts

27 Economic consequences $20 Billion annually in invasive insect damage & control Pimentel et al., 2005

28 Economic consequences $47 Billion for pathogens Pimentel et al., 2005

29 Discuss remaining questions from Gallardo et al Give one example of a biotic and an abiotic impact of an invasive species. 2. This study presents another meta-analysis. Define a metaanalysis and explain why the results are more reliable than a single study. 3. The authors describe accounting for publication bias. What publication bias do they refer to and why might it occur in invasion biology? 5. Describe one other piece of information you thought was interesting in this paper.