A Comparison of Spider Populations
Between Remnant and Reconstructed Prairies
Gregory R. VanNostrand and Rupert Giles
Department of Entomology, Iowa State University, Ames, Iowa
Abstract
As Iowa land is restored to natural prairie, we need to know just
how similar the reconstructed prairie areas are to the natural prairie
areas still in Iowa in terms of biodiversity. In this study, an attempt
is made to compare the biodiversity between remnant and
reconstructed prairies by looking at spider populations as
indicators. Spiders were identified from sweepnet samples taken
monthly from eight prairies. The study was conducted from MayAugust 2006 and May-August 2007. The data showed a difference
between individual numbers within spider families between the two
prairie types. In addition, there was a slight difference in overall
numbers of spiders caught (favoring the remnant prairies) but the
difference was not large enough to make a solid conclusion and we
determined that further research is needed.
Introduction
Much of the land in the state of Iowa was originally prairie. Today, very little of
that original prairie is left and as it disappears the natural flora and fauna of Iowa
diminishes. Many have seen the value of maintaining the natural biodiversity in
the ecosystem. As such, laws are in place to ensure that no more prairie is lost
in Iowa. As a condition of the conservation laws in the state, if prairie land is
developed an equal amount of natural prairie must be constructed elsewhere to
compensate. In addition, many private land owners have converted land back to
prairie to increase natural habitat in Iowa.
With these events happening in Iowa, a question that should be addressed has
arisen. Do the reconstructed prairies have the same quality and biodiversity as
remnant prairies in Iowa? In an effort to answer this question, we will look at
members of the Arachnida class. We theorize that reconstructed prairies will
contain fewer arachnid populations than comparable remnant prairies.
2
Materials and Methods
Eight prairies were selected for this study. There were four reconstructed
prairies and four remnant prairies. The reconstructed prairies we sampled are
Stargrass prairie located in central Iowa near the city of Ames, Colo Bogs prairie
near Colo, IA, Mama prairie near Newton, Iowa, and Airport prairie located in the
Chichaqua bottoms area of Polk County. The prairies sampled to represent
remnant prairies are Liska Stanek prairie near Fort Dodge, IA, Turtlehead Fen
prairie located in the Chichaqua bottoms, and two prairies from the Story County
area – Doolittle prairie and Boone Railroad Prairie. These prairies not only
represent reconstructed and remnants, but are also examples of both private and
state maintained prairies. Each of the eight prairies was sampled during the
summer months of May through August. This study was conducted for two
years; year 2006 and 2007.
When sampling for each prairie, three random locations were selected in the
prairie that maintained a distance of at least fifty feet from the borders. For each
location, a tape measure was extended in a random direction to a length of
eighty feet. Once the tape was laid down, we took a sweep net sample of twenty
sweeps spaced evenly over our eighty-foot sampling area. The contents of the
samples were placed into ziplock bags and labeled appropriately. The arachnid
specimens were later sorted out of each sweepnet sample, identified to Families,
and placed in ethyl alcohol containers in labeled for each sample. The data
obtained from the sweepnet samples spanning the two summers was analyzed
and is shown next in the results section.
Results
Table 1.1 2006 Sweepnet Samples
Remnant
Reconstructed
Salticidae
76
81
Thomisidae
76
46
Oxyopidae
23
19
Araneidae
150
62
Linyphiidae
61
15
Lycosidae
5
1
Philodromidae
12
17
Tetragnathidae 11
2
Anyphaenidae
0
0
Clubionidae
0
1
Dyctinidae
0
0
Unkown Spider 1
2
*Opiliones
5
1
Total
421
247
Table 1.1 compiles the number of specimens from each Family from the remnant and
reconstructed prairie sweepnet samples in 2006
3
Table 1.2 2007 Sweepnet Samples
Remnant
92
45
5
211
5
1
6
11
2
0
22
Reconstructed
175
52
7
154
1
1
19
8
9
1
2
Salticidae
Thomisidae
Oxyopidae
Araneidae
Linyphiidae
Lycosidae
Philodromidae
Tetragnathidae
Anyphaenidae
Clubionidae
Dyctinidae
Unkown
Spider
6
8
*Opiliones
3
2
Total
409
439
Table 1.2 compiles the number of specimens from each Family from the remnant and
reconstructed prairie sweepnet samples in 2007
Table 2 Combined 2006-2007 Sweepnet Samples
Salticidae
Thomisidae
Oxyopidae
Araneidae
Linyphiidae
Lycosidae
Philodromidae
Tetragnathidae
Anyphaenidae
Clubionidae
Dyctinidae
Unkown Spider
*Opiliones
Total
Remnant
168
101
28
361
66
6
18
22
2
0
22
7
9
810
Reconstructed
256
98
26
216
16
2
36
10
9
2
2
10
8
691
Table 2 shows the combined specimen count from each Family for both years
Specimens Identified
Specimens Identified
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
60
70
80
90
Thomisidae
Oxyopidae
Araneidae
Linyphiidae
Lycosidae
Philodromidae
Araneae Families
Tetragnathidae
Thomisidae
Oxyopidae
Araneidae
Linyphiidae
Lycosidae
Philodromidae
Aranea Families
Figure 1.2 shows specimen samples collected in 2007 from remnant prairies only.
Salticidae
Tetragnathidae
Figure 1.2 2006 Remnant Praires
Figure 1.1 shows specimen samples gathered in 2006 from reconstructed prairies only.
Salticidae
Figure 1.1 2006 Reconstructed Prairies
Anyphaenidae
Anyphaenidae
Clubionidae
Clubionidae
Dyctinidae
Dyctinidae
Spider Unknown
Spider Unknown
*Opiliones
*Opiliones
4
S p e c im e n s Id e n tifie d
lt
d
ic i
ae
o
Th
m
d
isi
ae
Ox
yo
d
pi
ae
Ar
an
a
e id
e
y
L in
ph
a
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co
r
od
om
Te
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e
i da
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ag
at
ha
yp
ae
An
d
hi
Aranea Families
h il
e
P
a
sid
e
ub
Cl
e
da
ni
io
d
ni
ae
Dy
c
ae
id
Sp
id
ti n
e
n
rU
k
w
no
n
Figure 1.3 displays the information from the previous two figures for a side-by-side comparison.
Sa
0
20
40
60
80
100
120
140
160
Figure 1.3 2006 Sweepnets
*O
p
ne
il io
s
Rconstructed
Remnant
5
Specimens Identified
Specimens Identified
0
50
100
150
200
250
0
20
40
60
80
100
120
140
160
180
200
ae
id
is
m
o
Th
ae
id
op
xy
O
ae
id
ne
ra
A
ae
id
hi
yp
n
Li
e
da
si
co
y
L
ae
id
th
na
g
tra
Te
Aranea Families
ae
id
m
ro
d
lo
hi
P
ae
id
is
m
o
Th
ae
id
op
xy
O
ae
id
ne
a
r
A
ae
id
hi
p
ny
Li
e
da
si
co
y
L
e
da
hi
at
n
g
tra
Te
Aranea Families
ae
id
om
r
d
lo
hi
P
Figure 2.2 shows specimen samples gathered in 2007 from remnant prairies only.
ae
id
tic
al
S
e
da
ni
ae
h
p
ny
A
ae
id
en
a
ph
ny
A
Figure 2.2 2007 Remnant Prairies
Figure 2.1 shows specimen samples gathered in 2007 from reconstructed prairies only.
ae
id
tic
al
S
Figure 2.1 2007 Reconstructed Prairies
e
da
ni
io
b
lu
C
ae
id
on
bi
u
l
C
e
da
ni
ty
ic
D
e
da
ni
ty
ic
D
n
w
no
nk
rU
de
pi
S
n
w
no
nk
rU
de
pi
S
s
ne
lio
pi
*O
s
ne
lio
pi
O
*
6
Specimens Identified
0
50
100
150
200
250
S
ae
id
om
Th
is
ae
id
i
op
xy
O
e
da
A
e
da
ei
n
ra
ae
id
hi
p
ny
Li
ae
sid
o
c
Ly
ae
id
ae
id
th
a
gn
tra
e
T
Aranea Families
il
Ph
m
ro
od
yp
An
i
en
ha
e
da
Cl
ae
id
on
i
ub
Figure 2.3 displays the data from figures 2.1 and 2.2 for a side-by-side comparison.
tic
al
Figure 2.3 2007 Sweepnets
Di
ae
id
yn
t
c
U
er
id
p
S
wn
no
nk
*O
s
ne
lio
i
p
Reconstructed
Remnant
7
id
lt ic
T
m
ho
ae
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isi
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ae
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d
pi
a
Ar
ae
n
p
in y
e
L
a
e id
h
a
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e
e
di a
d
hi
t
a
ae
Aranea Families
a
sid
e
e
es
ae
wn
n
in d
o
in da n ida
ilio
m
y
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kn
e
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t
i
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dr
gn
Ly
*O
Di
ph C lu
rU
y
ih lo
rt a
e
n
id
A
P
Te
Sp
e
Figure 3 combines the information from Figure 1.3 and from Figure 2.3 to show the full data summary of the study.
Sa
400
350
300
250
200
150
100
50
0
Figure 3 Two-Year Sweepnet
Remnant
Reconstructed
8
S p ecim en s Id en tified
9
*Opiliones is included, but not an Araneae family. It represents another order of
arachnids and contains the closely related “harvestmen” spiders that were counted
in this study.
Discussion
Tables 1.1, 1.2, and 2 show the numbers of spiders identified sorted by Araneae
family. As shown in the results section, there were eleven families found in the
sweepnet samples. The spider unkown category consists of specimens that
couldn’t be identified to family due to one of several reasons; and as noted at the
end of the results section, Opiliones are a different order of arachnids that are
closely related and were also counted in the study.
There was a significant difference between remnant and reconstructed prairie
data from 2006. With about one hundred-seventy more spiders caught in
remnant prairies, it appeared as though remnants contained larger populations
than the reconstructed prairies. However, there was little difference between
spider populations from either group of prairies in samples from 2007. When
combined, the data from the two-year sampling still shows more individual
spiders caught in remnant prairies, but the difference is low enough that no
strong conclusion can be made. Our original theory that remnant prairies contain
higher populations of spider due to higher biodiversity may still hold, but further
research is required. Sampling from an even greater selection of prairies and
conducting it for several more seasons would be ideal for gathering data to
confirm or reject our theory.
One interesting trend that can be seen with the data is the apparent difference
between the families that are found within each prairie. The major representation
of this can be seen between the families Salticidae and Araneidae. Salticidae is
the family that claims the jumping spiders and is the largest family of spiders.
Araneidae is the family for the orb weavers and many are familiar with the large,
round webs theses spiders make in their gardens. The two families display two
different hunting strategies, Salticidae are active hunters while Araneidae are
trappers. From this data, it seems that Araneidae are better competitors than the
Salticidae in remnant prairies. Likewise, Salticidae do better in the reconstructed
prairies. One possible explanation for this relationship could be that web-building
spiders are slower to establish in an area than the spiders that actively hunt.
Again, further study like what is discussed above will be more conclusive as to
why this difference appears.
10
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To: W. Scott Thune
From: Greg VanNostrand
Subject: Individual Project Scenario
Date: May 1, 2009
In my scenario, I am a researching Entomologist for Iowa State University. My
interest as a conversationalist has led me to conduct field research on
differences in spider populations between natural prairies that have never been
disturbed, and prairies that were once developed and are now restored back to
prairie.
This is a paper for publication in a scientific journal that details my research thus
far. This being the case, this is written for the biological science community and
will probably not be read outside that community.
I have structured to fit the standard of most scientific publications. It includes the
sections: Abstract, Introduction, Material and Methods, Results, Discussion, and
References.
While this scenario is fictitious, the data I used came from data collected for a
different study conducted here at Iowa State that I was a part of.