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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
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
Introduction
• For Formica exsecta, much research is done on subjects like sex-ratio’s, 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. )
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
Methods• Flora
• Fauna
• Soil-depth
• C/N-ratio
• pH
• Temperature
• Soil Moisture
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
Methods
Soil depth
• Measure depth
• 5 times at each plot
• Random places
C/N ratio
• Take 1 soil sample at each plot
• Standard procedure
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
Methods
• We used ANOVA’s to look to the variance of the characteristics of the plots within the area’s and between the area’s
Results Floramost abundant fauna per area
0
0,2
0,4
0,6
0,8
1
High Low Controlarea
cove
rag
e
betula nana (1) empetrum nigrum (2) vaccinium uliginosum (2)festuca ovina (2) equisetum palustre (dead) (2) equistem palustre (alive) (2)andromeda polifolia (2) mosses (3)
Results FaunaFlora (pitfall) per area
0
5
10
1520
25
30
35
High Low Con
area
nr.
of
ind
ivid
ual
s Linypihiidea
Carabidae
Collembola
Staphylinidae (Stenus)
Aphidoidea
Acarina
Results Soil DepthAverage depth per area
0
10
20
30
40
50
High Low Control
area
avera
ge d
ep
th (
cm
)
Sum of
Squares df Mean Square F Sig.Between Groups 144.649 2 72.324 .516 .621Within Groups 841.787 6 140.298
Total 986.436 8
Results C/N-ratioaverage C/N ratio per area
0
50
100
150
200
High Low Control
area
avera
ge C
/N r
ati
o
Sum of
Squares df Mean Square F Sig.Between Groups 1301.238 2 650.619 .500 .630Within Groups 7800.821 6 1300.137
Total 9102.060 8
Results pHaverage pH per area
0
1
2
3
4
5
6
7
High Low Control
area
avera
ge p
H
Sum of
Squares df Mean Square F Sig.Between Groups .280 2 .140 .112 .895Within Groups 7.465 6 1.244
Total 7.745 8
Results TemperatureAverage Temperature per area
0
2
4
6
8
10
High Low Control
area
Avera
ge t
em
pera
ture
Sum of
Squares df Mean Square F Sig.Between Groups .740 2 .370 1.708 .259Within Groups 1.300 6 .217
Total 2.040 8
Results Soil Moistureaverage moisture content in soil
50,0
60,0
70,0
80,0
90,0
100,0
High Low Control
area
averag
e m
ois
ture i
n s
oil
(%
)
Sum of
Squares df Mean Square F Sig.Between Groups .000 2 .000 .037 .964Within Groups .018 6 .003
Total .018 8
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
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
Discussion
• The settlement and abundance of ants (hills) doesn’t 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.
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)
Discussion
• Variance within area’s 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
Take Home Message• No significant results found
• Settlement and abundance of ants isn’t 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!
Time to rest!
Credits:
• Deze powerpoint is gemaakt door:– David van Diepen
• Kijk voor meer powerpoints op:– www.davidvandiepen.nl
Ik vind het leuk als u een berichtje achterlaat op mijn gastenboek!
