Densities of Arthropods under Different Types of Coverage

at Rice Woods in NE Baldwin CityAndrew Miller

Biology Department, Baker University, Baldwin City, KS 66006

Abstract

Arthropods are invertebrates of the phylum Arthropoda. Arthropod density determines the total

number of organisms within a certain area. The area was determined by the type of coverage the

organisms were found under. The question addressed in this experiment was, are the densities of

arthropods higher under certain coverage than the other. The resulting data from the experiment

showed that more arthropods were denser under the wood coverage than the metal coverage.

Introduction

The density of arthropods has been a heavily focused upon aspect of forest ecology. Previous

experiments have implicated the importance of knowing density of arthropods in different

habitats. The overall effect on wood or deadwood as a cover or source of food has also been a

studied part of past ecology (Jabin 2004). Deadwood is a known habitat for multiple arthropods

and is an effective cover to produce high densities of arthropods. Metal covers were also used in

this experiment and a similar study was done using zinc coverings that showed that large

arthropods were not readily seen as micro invertebrates were (Strojan 1978). The metal or zinc

coverings were supportive of micro invertebrates, but not the large arthropods that were tested in

this study. This relates to the ecology of the rice woods because the coverings placed throughout

the forest floor could now be an effective habitat for the arthropods that are present. If the wood

provides a house and nutrients for the arthropods then it is part of the environment, if the metal

covering has a high density as well that could indicate an effective habitat as well. The

information provided by previous research lead me to create the following hypothesis. My

hypothesis that will be tested will be that wood coverings will have a higher density of

arthropods than the metal covering. My null hypothesis is there will be no difference between the

density of a wood covering and metal covering on the forest floor.

Study Area

The study area was located in the University of Kansas Biological Reserve, Rice Woods, located

two miles Northeast of Baldwin City, in Douglas County, Kansas.

Methods and Materials

Arthropods were sampled within the woods using two different materials as cover (Figure 1).

The two different materials that were tested were wood and metal. These coverings were

randomly place throughout the woods by the University of Kansas research team, so the time

needed for the coverage to become part of the environment was already accounted for. I chose

one metal and one wood piece of coverage for this experiment. When one metal piece and one

wood piece were located, measurements were able to be taken. The measurements were taken by

counting the organisms individually. This ensured an accurate count of organisms so the

densities could be calculated.

The densities of the arthropods were measured using a density calculation that took the number

of organisms per unit area or piece of coverage and divided that by the overall length and width

or area of the coverage. This provided a calculation of the density and provided a number that

could be compared between the two.

Results

The average density of the wood coverage showed to be substantially higher than that of the

metal covering (Table 1). The wood showed to be 61.3 insects per m² while the metal had just

10.6 insects per m². The total numbers of organisms under each individual covering respectfully

are shown using graph 1.

The total organisms might have shown a much higher population density regarding the wood

covering, but the metal coverings had higher numbers of beetles and chilpoda. This could be

random or could show those organisms had a preference for the metal covering. The

armadillidiidae number was much higher on the wood covering and increased the overall

population density greatly.

Discussion

The hypothesis was supported in this case. The different types of coverings did make a

difference on the densities of organisms. The wood covering was more densely filled. The metal

one was sparsely filled with organisms. This could be explained by saying that organisms are

more likely to build a home where there is a wood coverage. Whether it is the wood has nutrients

or the fungus on the wood has nutrients, the wood could just make a more suitable habitat. The

metal could not support nutrients as well as the wood and may have a less suitable habitat. The

research done in the past shows those organisms such as ants and other organisms that live in the

litter layer can use the wood as a source of nutrients or use them to make their home, such as ants

(Keck 2008). This could also explain why the metal covering was not as densely used because it

did not have the benefits that a wood cover could offer. The experiment could also be slightly

unreliable due to the lack of raw data. Only one wood cover and one metal cover were selected.

More than one of each should have been tested to more accurately show the results were valid.

Acknowledgements

Thank you to Dr. Scott Kimball for his help in guiding me through the research process and

feedback on statistical measurements.

Literature CitedJabin M, Mohr D, Kappes H. 2004. Influence of deadwood on density of soil macro-arthropods

in a managed oak–beech forest. Forest Ecology and Management (1) [Internet]. [2004

Jun, cited 2014 Nov 25] (194):(61-69). Available from:

http://www.sciencedirect.com/science/article/pii/S0378112704001161

Keck M. 2008. Good and Bad Bugs [Internet]. **Edition**. San Antonio(TX):AgriLife

Extension; [2008, cited 2014 Nov 25] . Available from:

https://insects.tamu.edu/youth/4H/Junior/Good_Bugs.pdf

Strojan C. 1978. The Impact of Zinc Smelter Emissions on Forest Litter Arthropods. Oikos

(**Edition**) [Internet]. [1978, cited 2014 November 25] (31):(41-46). Available from:

http://www.jstor.org/discover/10.2307/3543382?

uid=18808&uid=3739672&uid=2&uid=3&uid=18807&uid=67&uid=62&uid=3739256&

sid=21104717612821

Figure1. Shows the different types of coverage that was used on the arthropods. The image on the left is a wood cover and on the left is the metal cover.

Arthropod Wood Coverage Metal Coverage Population Density (Wood)

Metal

Diplopoda 4 0 3.5 0Chilpoda 0 1 0 1.125Beetle 2 3 1.7 2.6Ant 22 0 19.5 0Spiders 5 2 4.4 1.7Armadillidiidae 36 6 32 5.3Total 69 12Population Density

61.3 insects per m²

10.6 insects per m²

Table 1. The table shows the total number of arthropods per covering. This is also shows the population density based on the equation number of individuals/unit area.

Diplopoda

Chilpoda

Beetle

Spiders

Armad

illidiid

aeTo

tal05

101520253035404550

Wood CoverageMetal Coverage

Figure 2. Illustrates the total number of arthropods found under different types of coverage. The blue color illustrates the wood coverage and red illustrates the metal coverage. The graph reflects table 1.