Arthropod Communities: A Comparison between Invaded and Native Grassland Habitats

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Arthropod Communities A Comparison between
Invaded and Native Grassland Habitats

• Hannah Kistner Nicole Molinari Carla
  DAntonio
• Ecology, Evolution, and Marine Biology

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California Grasslands

• Once occupied 25 of the state
• Grasslands and inhabitants reduced by
• Agriculture
• Urban development
• Invasion of exotic species

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California Grasslands

• Exotic Species
• a species from another geographic region
• can be accidentally or intentionally introduced
• can exert negative effects

1980
2000
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Native vs. Exotic Grasslandsat the Sedgwick
Reserve
Mixed Species of Grasses

• Exotic Species of Grass
• Annual grass
• Homogenous
• Herbaceous species rare

• Native species of Grass
• Perennial bunchgrass
• Heterogeneous
• More herbaceous species

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Native vs. Exotic Grasslandsat the Sedgwick
Reserve
This invasion has negatively impacted PLANT
species diversity in the Sedgwick Reserve.
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Why arthropods?

• 1. Important food source
• 2. Functionally important
• -pollinators
• -decomposers
• -herbivores
• -predators

variety of arthropods
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Why arthropods?

• 1. Important food source
• 2. Functionally important
• -pollinators
• -decomposers
• -herbivores
• -predators

variety of arthropods
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Does Plant Invasion Impact Arthropod Diversity?

• Hypotheses
• 1. Pollinators Higher Diversity in Native
  Grassland
• 2. Herbivores Higher Diversity in Native
  Grassland
• 3. Predators Higher Diversity in Native
  Grassland
• 4. Decomposers Higher Diversity in Native
  Grassland
• The Number of Individual Insects and the Species
  Diversity will be greater in the Native Grassland
  because arthropods are dependent on plant
  populations, which are more diverse in the Native
  Grassland.

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Methods to Collecting Arthropods

• 5 100 m transects
• Each transect has 3 grassland types
• 1. Native
• 2. Mixed
• 3. Exotic

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Insect Collection in the Field

• Pit-Fall Trap

Anti-freeze
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Arthropod Classification
1. Pick a bug from the tray.
2. Pick a book that corresponds.
Pit-Fall Trap Tray
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Arthropod Classification
3. Beetles are Order COLEOPTERA in a dichotomous
key.
4. Follow the dichotomous key to Family. 11
antennomeres 4-5-5 tarsal segment pattern is
the Family TENEBRIONIDAE.
5. Use the key until functional group
(pollinator, herbivore, predator, or decomposer)
is determined.
biological classification levels
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Results
2. Which grassland type has the most insect
diversity?
The Exotic grass type has a lower diversity than
Mixed and Native grassland types.
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Results
2. Which grassland type has the most insect
diversity?
Mixed and Native grass types do not appear to be
different from one another.
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Comparing Data
They are very similar in that the Exotic type
tends to be smaller, and the Mix and Native types
are equal.
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Results
3. Which grassland type has the greatest number
of insects?
The Exotic grass type has a lower diversity than
Mixed and Native grassland types.
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Results
3. Which grassland type has the greatest number
of insects?
The Native grass type is higher in insect
individual numbers than the Mixed and Exotic
vegetation types.
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The Big Picture (Why do we care?)

• 95 of grasslands have exotic species
• If exotic species continue to expand, plant and
  arthropod species will be lost
• Impacts may continue up the feeding (trophic)
  levels
• Plants and Arthropods are affected
• Next could be birds, snakes, lizards, mammals,
  and arthropod dependent organisms.
• After thatwho knows?

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Reflections

• A scientist must curious enough about the world
  and how it works to answer her own questions.

6/15/08 Before

• Researched data takes patience to collect and
  perseverance to analyze.
• University research is a collaborative effort.
• Bugs are WAY cooler and more complicated than I
  thought (just put one under a microscope).

7/11/08 After
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Acknowledgements

• Nicole Molinari
• Carla DAntonio
• AR staff
• Lubi
• Anthony
• Leila
• Evelyn
• Barry Zhong