The Abisko Ant (Formica exsecta )

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The Abisko Ant(Formica exsecta )

• Can the presence and abundancy of ant hills be
  predicted by looking at characteristics of the
  area

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Introduction

• The Abisko Ant Formica exsecta (or Narrow-headed
  wood ant)
• Nests found at open heath land or moorland as
  well as scrub and forest clearings
• Nests are smaller than at other species (30x30
  cm) and are partly under the ground
• Nests made of vegetation fragments, in Abisko
  mainly Andromeda and Equisetum
• Dinner other insects or honey dew

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Introduction

• For Formica exsecta, much research is done on
  subjects like sex-ratios, but not on variables
  that are important for population bigness. So not
  much is known about that except for this common
  knowledge.
• But with this knowledge you would expect that you
  could predict the presence and abundancy of ant
  hills by looking at characteristics of the area
  (vegetation to build nests, other insects for
  food, enough room for building underground, etc.
  )

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Hypothese

• In Abisko, you have open moorland with High, Low
  and No population of Ant nests
• We expect that this is the result of that Ants
  choose their area by looking at characteristics
  of the area
• Thereby
• We expect that there is a correlation between the
  characteristics of the area and the occurrence of
  the ants

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Methods

• Flora
• Fauna
• Soil-depth
• C/N-ratio
• pH
• Temperature
• Soil Moisture

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Methods

• Flora
• Braun-Blanquet scale
• 1 plot near each hill
• 40x40 cm
• No visible influence of the ants
• Close enough to predict the same characteristics
  at the real ant spot
• Fauna
• 1 Pitt-Fall at each hill in same plot
• Fauna determination counting

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Methods

• Soil depth
• Measure depth
• 5 times at each plot
• Random places
• C/N ratio
• Take 1 soil sample at each plot
• Standard procedure

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Methods

• pH
• 1 soil sample at each plot
• Extraction of liquid with centrifuge
• Standard pH measurement
• Temperature
• 5 times at each plot
• Random places
• Soil Moisture
• 1 soil sample at each plot
• (total weight - dry weight)/ total weight

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Methods

• We used ANOVAs to look to the variance of the
  characteristics of the plots within the areas
  and between the areas

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Results Flora
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Results Fauna
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Results Soil Depth
Sum of Squares df Mean Square F Sig.
Between Groups 144.649 2 72.324 .516 .621
Within Groups 841.787 6 140.298
Total 986.436 8
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Results C/N-ratio
Sum of Squares df Mean Square F Sig.
Between Groups 1301.238 2 650.619 .500 .630
Within Groups 7800.821 6 1300.137
Total 9102.060 8
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Results pH
Sum of Squares df Mean Square F Sig.
Between Groups .280 2 .140 .112 .895
Within Groups 7.465 6 1.244
Total 7.745 8
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Results Temperature
Sum of Squares df Mean Square F Sig.
Between Groups .740 2 .370 1.708 .259
Within Groups 1.300 6 .217
Total 2.040 8
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Results Soil Moisture
Sum of Squares df Mean Square F Sig.
Between Groups .000 2 .000 .037 .964
Within Groups .018 6 .003
Total .018 8
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Discussion Results

• Flora ? much variation in areas themselves
• ? variation between also great, but not
  significant
• Fauna ? much variation in the areas and between
  the areas
• ? No significant result
• Soil depth ? high variation in areas, but smaller
  between areas
• No significant result
• C/N ratio ? C/N ratio lower in ant-areas than in
  control
• ? not significant because of high in-area
  variation

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Discussion Results

• pH ? no singificant difference between areas
• Temperature ? Area with high-ant abundancy has
  lower
• temperature, but not significant
• Soil moisture ? little difference between areas
• ? variation in control area greater than in
  ant areas

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Discussion

• The settlement and abundance of ants (hills)
  doesnt seem related to the research variables
• The depth is very variable due to the fact that
  the terrain below the soil is rocky.
• Maybe sunlight (and related place on the mountain
  side) and enough food resources are more
  important
• More research is necessary.

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Discussion

• Fauna has much in-group variation
• Too few fauna samples due to too little pitfalls
• Pitfalls could have had more result if they could
  stand for an extended period of time
• Other catching methods?
• Vegetation has much in-group variation.
• Possible solution? taking more samples per area
  to average (power problem)
• C/N ratio has much in-group variation.
• Possible solution? taking more samples to average
  C/N ratio per area (power problem)

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Discussion

• Variance within areas looks like a factor that
  might be important, but too few freedom degrees
  to proof something
• Maybe Ants don't care about the characteristics,
  its known that ants in a certain amount can
  create there own environment en maintain moist
  and temperature within the nests and the
  population answer must be searched in other
  explanations like relation
• we looked at random locations within the control
  area, but ants might only look at the unsuitable
  border of a terrain
• At last, the examined plots could differ from the
  real plots, but it is impossible to look at the
  former characteristics

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Take Home Message

• No significant results found
• Settlement and abundance of ants isnt related to
  soil depth, pH, soil temperature, soil moisture
• (although variance might be a factor)
• Settlement of ants can be related to flora and
  fauna, but more samples are needed
• Other area characteristics or totally other
  explanations might be important
• So better and more research!

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Time to rest!
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Credits

• Deze powerpoint is gemaakt door
• David van Diepen
• Kijk voor meer powerpoints op
• www.davidvandiepen.nl
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