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Effects of Simulated Herbivory on Alliaria petiolata

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Effects of Simulated Herbivory on Alliaria petiolata Ashley Paschal, Brian Scott, Kyle Burns, and Tyler McPheters – PowerPoint PPT presentation

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Title: Effects of Simulated Herbivory on Alliaria petiolata


1
Effects of Simulated Herbivory on Alliaria
petiolata
  • Ashley Paschal, Brian Scott,
  • Kyle Burns, and Tyler McPheters

2
Background
  • Problems with invasive species
  • Cause a decline in native populations
  • Leads to a loss of biodiversity
  • Difficult and expensive to manage

3
Garlic mustard invasion
  • Eradication might be nearly impossible for
    colonized sites
  • Autogamous breeding system, high seed production,
    and rapid growing season (Anderson et al. 1996)
  • Successful in outcompeting other plants (Meekins
    and McCarthy 1999)
  • High tolerance to environmental variation
    (Meekins and McCarthy 2001)

4
How do we get rid of them?
  • Non-biological eradication
  • Fires, herbicides, floods, and mowing
  • Possibly effective, but damaging to surrounding
    environment
  • Biological controls
  • Host-specific herbivores might be a suitable
    solution (Blossey et al. 2001)

5
Deciding on a control
  • Simulated herbivory
  • Benefit from controlling multiple variables
  • Better understanding what types of herbivores are
    effective (Baldwin 1990)
  • Rebek and ONeil (2005)
  • Simulated herbivory shortens lifespan and
    decreases biomass of garlic mustard

6
Our study
  • How does simulated herbivory affect garlic
    mustard populations in the DePauw Nature Park?
  • Hypothesis Increased herbivory will reduce
    survival, growth, and reproduction of garlic
    mustard
  • Indicated by differences in height, above-ground
    biomass, and flower number

7
Methods
  • Location DePauw Nature Park Creekside Trail.
  • Initially labeled 40 plots that contained at
    least three (3) rosettes of garlic mustard
  • (Hula-hoop sized plots)
  • Labeled one plant in each plot as control, low,
    and high.
  • Counted leaves on each plant and then performed
    treatments.

8
Methods Treatment
  • Standard holepunch
  • Half of leaves from the two treatment levels were
    punched
  • Low One fourth of leaf area removed.
  • High Half of leaf area removed

9
Methods
  • Measured light intensity using a light meter
  • Measured soil moisture levels
  • Post-treatment
  • Number of flowers, height of plants, and
    above-ground biomass.

10
Methods
  • Statistical Analysis
  • Pearson Correlations
  • ANOVA

11
Results
F 0.530 P gt 0.05
12
F 2.861 P gt 0.05
13
F 0.229 P gt 0.05
14
Correlation Data
15
Significant Correlations
  • Initial height was correlated with density, total
    number of leaves, number of flowers, final
    height, and biomass.
  • Final height was correlated with number of
    flowers, and biomass.
  • Biomass was correlated with number of flowers.
  • There was also a correlation between initial
    number of leaves and amount of sunlight.
  • Flowering date was not correlated with the
    different treatments. Most plants had flowered
    by March 20, 2006 and the remainder had flowered
    by March 27, 2006.

16
Discussion
  • Our low herbivory and high herbivory treatments
    showed no significant effects on garlic mustard
    plant height, biomass, or number of flowers
    (pgt0.05)
  • No significant ANOVA tests, so plants started off
    comparably and treatments did not detectably
    affect growth or reproduction

17
Discussion
  • Many obvious correlations between response
    variables and initial variables
  • i.e. initial number of leaves and initial height
  • Less expected but significant correlation seen
    between plant density and height

18
Discussion
  • Published results have used different methods
  • Rebek and ONeil 2005 Effects of simulated
    herbivory on A. petiolata.
  • Study on manual flower shoot damage
  • Led to decreased plant size and reproduction.
  • Bossdorf et al. 2004 Leaf removal led to
    reduced production of seeds and fruits.
  • 75 of leaf removal reduced fitness to 81 of
    that of controls.

19
Implications
  • Results imply that the level of simulated
    herbivory used was not effective
  • Currently there are no herbivores in the Nature
    Park that eat garlic mustard
  • If we were to introduce an herbivore, it would
    have to more drastically affect garlic mustard to
    be successful in controlling the garlic mustard
    population

20
Implications
  • Garlic mustard is currently affecting the native
    species of plants at the DePauw Nature Park, so
    it is important to control garlic mustard
  • Control of garlic mustard important also for
    regeneration of forest
  • New York Times article (May 2, 2006) says that
    GM disrupts interactions between tree seedlings
    and soil mycorrhizae

21
Recommendations
  • Other strategies for removal of garlic mustard
  • pulls, herbicides, controlled fire
  • Small, isolated patches that are more manageable
    should be controlled to prevent spread
  • Rim trail patches in contrast to rail trail
    flourishing populations

22
Works Cited
  • Baldwin, I.T. 1990. Herbivory simulations in
    ecological research. TREE 5 91-93.
  • Bossdorf, O., S. Schroder, D. Prati, and H. Auge.
    2004. Palatability and tolerance to simulated
    herbivory in native and introduced populations of
    Alliaria petiolata (Brassicaceae). American
    Journal of Botany 91 (6)856-862.
  • Blossey, B., V. Nuzzo, H. Hinz, E. Gerber. 2001.
    Developing biological control of Alliaria
    petiolata (M. Bieb.) Cavara and Grande (garlic
    mustard). Natural Areas Journal 21 357-367.
  • Meekins, J.F., and B.C. McCarthy. 1999.
    Competitive ability of Alliaria petiolata (garlic
    mustard, Brassicaceae), an invasive,
    nonindigenous forest herb. International Journal
    of Plant Sciences 160 743-752.
  • Meekins, J.F., and B.C. McCarthy. 2001. Effect
    of environmental variation on the invasive
    success of a nonindigenous forest herb.
    Ecological Applications 11 1336-1347.
  • Rebek, K.A., and R.J. ONeil. 2005. Impact of
    simulated herbivory on Alliaria petiolata
    survival, growth and reproduction. Biological
    Control 34283-289.
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