Transcript The Effect of Perching Availability on Density of Dragonflies at Taylor

Comparison of Odonata Populations in Natural and
Constructed Emergent Wetlands in the Bluegrass Region of
Kentucky
Brittany A. Brookshire, Department of Biological Sciences, Eastern Kentucky University
Dr. David Brown, Mentor
Introduction
Results
Wetlands provide valuable hydrological functions and provide valuable niches for many
small species of animals, including dragonflies (Biebighauser 2011). Without wetlands
serving as reproductive habitat the dragonfly population would decrease exponentially.
Research has shown that in the past forty years Kentucky has lost up to 80% of its own
natural wetlands (Brown & Richter 2012).
My data collection ran over a six month period of time, from May2013-October2013. Over that
period of time I:
 Performed 60 Odonate Surveys
 Completed 20 KY-WRAM surveys
 Counted a total of 1275 Odonates (883 dragonflies & 392 damselflies)
 Saw of total of 32 Odonate species (Some of which were new species records for Madison
county)
The wetlands differed in diversity and species richness from season to season, with the artificial
wetlands having more species and more Odonates per wetland for almost every season.
Wetlands provide:
 Niches for small mammals, insects, amphibians and birds
 Hydrology and flood prevention for surrounding areas
 Habitat and resting areas for Migratory Waterfowl.
Separated Simpsons Diversity
Separated Shannon Diversity
0.3
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
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0
0.25
Diversity
OBJECTIVES- My objective in this research is to measure the Odonata populations at
various natural and artificial emergent wetlands and to compare these populations to
biotic and abiotic variables such as hydrology, vegetation types and wetland condition. I
believe that if the wetlands being studied prove to be healthy then the dragonfly and
damselfly populations at the individual wetlands will be high in species richness and
diversity, while the wetlands that are less healthy will have a low species richness and
diversity.
Diversity
Odonates could be important to discovering many of the variations between natural and
artificial wetlands. Dragonflies and Damselflies are sensitive to environmental
conditions, therefore they can act as biological indicators.
0.2
0.15
0.1
0.05
0
Spring
Summer
Season
Fall
Art
Spring
Nat
Summer
Season
[Figure 4]
Fall
Artifical
Natural
[Figure 5]
The wetlands were also assessed using the KY-WRAM, with artificial wetlands scoring an average of
46.3 out of 99 and natural wetlands scoring an average of 51.8 out of 99. The scores were compared
using a t-test and were not found statistically significant (T= 1.183, P = 0.252). In scatter plot [Figure
6],the relationship between wetlands condition as measured by KY-WRAM and odonate species
richness is trending negative, but is not statistically significant (T-2.16, P=0.044, df = 1, R^2 = 0.06).
KY-WRAM and Richness
80
70
KY-WRAM
60
[Figure 1]
Methods
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20
In this study, that extended from January 2014- December 2014. I collected data on the
population size of Odonates in 20 different wetlands in the Bluegrass Region of Kentucky.
Ten of these wetlands were natural emergent wetlands and ten were constructed
emergent wetlands. All of this data will be gathered during three different sampling
periods: spring (May-June), summer (July-Aug), and fall (Sept-Oct).
The KY-WRAM rapid wetland assessment method was also used at the 20 wetlands to
surmise the health of the wetlands being surveyed.
Below [Figure 2] is a map of all twenty wetlands. The green dots represent natural sites and red dots
represent constructed sites. Also [Figure 3] is one of the twenty wetlands.
10
0
0
50
100
150
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250
Richness
[Figure 6]
Discussion
My results differed from my original hypothesis in that the artificial wetlands had higher Odonata
numbers and a higher number of species. I believe this is partially due to the hydrology and plant
communities of the artificial wetlands. They are typically filled with water for longer periods of time
than natural wetlands. Odonata are dependent on year-round water availability. Some of the natural
wetlands likely dry out completely during late-summer. Thus, the artificial wetlands may be more
suitable to odonates because of a more stable hydrology.
Another surprising result was that the season with the higher diversity was the autumn, and not the
summer, as was expected. This may be because many Meadowhawk dragonflies and some other
species were detected in the autumn but not during the summer.
In regards to the imitations to this study, animal interference and alterations to study sites was an
interesting change. Some of my study sites were altered and Odonates killed due to the
interference. Weather was another limitation, with a high year of rainfall and the early frost in
October killed many odonates early.
Possible Management implications for this project is the use of Odonates in Urban areas, and its
implications for wetland conservation by gathering more information.
[Figure 3]
[Figure 2]
Works Cited
Biebighauser TR (2011) A Guide to Creating Vernal Ponds. Morhead (KY): USDA Forest Service. 6 p.
Brown DR and Richter SC (2012) Meeting the Challenges to Preserving Kentucky's Boidriversity. Sustain 25: 27 p.