The Environmental Science Graduate Students at Watlings Castle, San Salvador, Bahamas.(TME 98)
Bachelor Reserve is a perfect example of ecological succession. From the late1930's and on, portions of the Bachelor Reserve were utilized by farmers forgrazing cattle and for growing crops. Since then the barriers that were chosenfor crops moved and some areas of the reserve were "let go." When aportion of land is "let go" it is no longer tilled, grazed, orutilized for agriculture in any way. A portion of land is "let go"because of a sale of land or possibly an occupational change of the owner.Essentially what results over time is what would have happened had man notinterfered in the first place; a forest is born. All of the sections that wewill be studying at Harker's Run were primarily forest before the 1930's.Farmers utilized these sections of land in the past for agriculture andunknowingly caused a disturbance in the species diversity of invertebrates. Byremoving many of the trees that many invertebrate species rely on, farmersindirectly eradicated many if not all of the insects that relied on them. Ourmission is to find out if there is a correlation between the diversity ofinvertebrates in the leaf litter and the amount of time the land has had toregenerate at Harker's Run. Our hypothesis is that the amount of diversity willhave a positive correlation with the amount of time the area has had to recover.We also think that we will find more invertebrate diversity within the areasthat have had the most time to regenerate. We plan on providing certifiableevidence about the correlation between species diversity and forest regenerationperiods.
This is interesting to us because we are learning how the size of anecosystem impacts the species diversity found there. The Song of the Dodo byDavid Quammen has introduced the idea of island biogeography and shown howlarger islands in general have more species and that older islands often havemore diversity. The closest thing to an island chain near Oxford2C Ohio that wehave found to study is The Joseph M. Bachelor Reserve. We want to try and provethat the areas with the earliest succession in the reserve show the mostdiversity among invertebrates. Although this area is not divided by ocean we canthink of the reserve as a series of islands because over the past 100 yearsdifferent areas have been segmented off and used for different things Üfarming, grazing, agriculture, and let go. In addition it shows us that MiamiUniversity is concerned with protecting nature.
Bachelor reserve and the surrounding areas have over the years gone throughseveral years of natural succession. Succession, according to Mules, is definedas "the gradual change in plant and animal communities in an area followingdisturbance or the creation of new substrate." In this case the disturbancewas the conversion of temperate woodland into farmland. The natural progressionfrom farmland to deciduous forest is called secondary succession. We are goingto observe different levels of succession in three areas around Bachelor reservethrough observations of insect diversity in the leaf litter. The diversity ofall organisms in a community is essential to the stability of that community. Atthis time it is impossible to predict the abundance and types of insects we willsee without having taken any samples. The insects that we will gather will allbe examples of organisms that colonized the areas in Bachelor Reserve during theearly stages of succession and were able to survive and reproduce. Many of theinvertebrates we are going to find at Bachelor reserve will be arthropods.Arthropods are invertebrates with jointed legs such as beetles, ants, spiders,mites, and centipedes. We could possibly find any number of these organisms inour samples taken at Bachelor Reserve. Arthropods are beneficial to the soil andoverall ecosystem of the forest because the cycle nutrients for plants, bacteriaand other fungi. In terms of succession the arthropods are important becausethey feed on bacteria that release nutrients into the soil. When the arthropodsconsume the dominant bacteria it allows other soil bacteria to take it's placethus increasing the amount of organisms breaking down organic matter in thesoil. This process helps prepare soil that was once farmland, sapped of itsnutrients by the crops, to become more hospitable for plant succession and there-establishment of the temperate woodland ecosystem. Early in our experiment wewill provide background information about the organisms that we will bestudying. We will utilize our samples to guide our research of invertebrates.
We plan to look at succession and its relationship with species diversity ina protected landscape owned by Miami University. The Joseph M. Bachelor Reserve,which is 661 acre area just east of Oxford, between state route 73 and BonhamRd. This patch of land has a very important history. Joseph M. Bachelor was anEnglish professor at Miami from 1972 through 1946. His home was the BachelorEstate and accounted for 400 acres of what is now Bachelor Reserve. When hedied, Professor Bachelor, left all the lands and funds associated with theestate to Miami University. In 1947, when Miami acquired the land, 50% was beingfarmed and 20% grazed. Over the years Miami has acquired more land and added tothe reserve. The land has had many uses and therefore gone through many changes.Human disturbances, like the removal of existing plants to turn a field into acropland or an agricultural grazing land fragment the landscape. ThereforeBachelor Reserve can be thought of as many little islands. The fact thatdifferent patches of the land has been used for different things over the past100 years or more creates many little individual ecosystems within one. Thechanges have been recorded since 1938 until the present. Past research has beendone in this area and a Landscape Guide, by a Miami University UndergraduateSummer Scholar's Project in 1995, by Lori M. Gramlich, will be a very importanttool for us. She has divided the reserve into 10 scenes and 2 Ecotones. We willbe using scene 1 and 4 of hers and one we have selected ourselves.
"Scene 1" is a Floodplain Forest. The forest show's the mostsuccessional change we suspect we will find the most invertebrate diversityhere, because it hasn't been grazed or farmed since 1938. The major disturbancein this area would be flooding and changes in the path of Harker's Run (a streambed). There is evidence that the area has been a mature forest since at least1938 and the fact that there is a presence of sycamores and other older trees,shows that no cutting or other drastic human disturbances have taken place. Thesoils in this area change from sand to clay as the distance from the bank of thestream increases. The vegetation in this area can be clearly divided into acanopy, sub canopy, and herb layer. The canopy layer is mostly composed ofsycamores, while the sub canopy trees are smaller and mostly Hackberry, elm, andbox elder. The area receives an abundant amount of light for a forest area andtherefore has a successful herb layer. This layer is made up of native speciessuch as Miami mist, big-leaf waterleaf, maple-leaf waterleaf and a competingexotic herb garlic mustard.
"Scene 4" is a Young Floodplain Forest. It is at the base of adeciduous forest slope. Older forest completely surrounds the young forest andthe young forest's boundaries are marked by fence lines. There is a lowbackwater area to provide moisture to the soils. The soil texture here is muchfiner than that found in Scene 1. A one-year leaf litter layer covers the forestfloor from woody debris of the older trees. The dominant plants in this area areshrubs and saplings. The dominant saplings are young black and sugar maples,while the most abundant shrubs are Amur and honeysuckle. There are some oldertrees similar to those found in scene 1 like: Elm, sycamore, and box elders.However there is a big difference between scenes 1 and 4. The forest found inscene 4 is less than 30 years old. Even the largest sycamores are smaller thenthe smallest ones found at scene 1. The young forest was farmed through 1968 aspart of a plan to farm the bottomlands, by 1976 the land was no longer used forfarming and succession began. In 1983 the scene was classified as a youngforest. There is evidence that farming did not exhaust the nutrients in the soilsince a young forest has generated so quickly. We suspect this scene will have amiddle amount of invertebrate diversity compared to our other two islands.
Our "own" scene is a field used for farming. It is situated about 1mile into the reserve and found to the west between scenes 1 and 2 (as mappedout on the walking tour). The farmland was used for a soybean crop this pastyear and appears to have been used for corn the year before. The soybean is mostlikely part of a crop rotation in order to save the soil from nutrient loss andwind erosion. We will expect to find the least invertebrate diversity herebecause there has been no succession recently and there is little plantdiversity here.
Our experiment ties into a variety of larger themes such as succession,diversity, and human impact on habitat. If we were to study further we wouldfind that these subjects may be correlated in a way to depict how humans haveaffected natural ecosystems. On the positive side Miami seems to have done itspart in trying to preserve the area of land designated presently as the BachelorReserve. Conversely, this landscape was previously impacted by humans foragricultural purposes. Is it true that this reserve is saving this land fromecosystem decay? Humans have turned a forest into farmland and farmland backinto forest. Are we solving a problem or are we, as Quammen implies, making afutile attempt to reconnect the torn patches of nature's quilt?Methods and Materials:
1. 3 Funnels or Gallon milk jugs
2. 3 Lamps
3. 3 Wire screens
4. 3 Small receptacles filled with ethyl alcohol
7. Trash bags
8. Specimen jars
9. Petree dishes
10. Dissecting microscope
11. Cheap Vodka
We surveyed the Bachelor Reserve on the 20th of September and after referringto a study previously done by a Miami graduate, we chose our 3 scenes. Scene 1 and Scene 4 were identified on the walking trail and the soy-field weselected ourselves. We obtained samples on the following dates: October13, November 1, and November 8. At each site we made a 1/2m by .26mtransect and collected the leaf litter into trash bags. Differenttransects were selected from within the scenes for each sample giving us a totalof nine transects. Gathering leaf litter from different transects withineach scene helped to give a better representation of each scene's diversity andeliminate bias. After gathering the leaf litter we returned to the laband sorted the samples utilizing our Burlese Funnels as well hand-sorting.
We set up a Burlese funnel by a piece of wire screen in the bottom of a funnel(or milk jug) to support the soil. We then inserted the leaf litter and waited.Due to the shortage of ethyl alcohol, we placed the receptacle filled with cheapvodka under the funnel. Mounted above the receptacles a light was placed toencourage the insects to move towards the bottom of the funnel and into thevodka. Most organisms in the sample should have crawled through the screen and fall into the ethyl alcohol,thus being preserved, however after several hours passed we resortedhand-sorting the samples. After sorting and preserving all of our sampleswe identified all the organisms into species and recorded our information in adata sheet. The information in the data sheets was used to calculatespecies diversity, via the Shannon-Weiner Diversity Index, and speciesrichness. We also performed a Spearman Rank test on a compiled list of thetop ten species for each scene and created graphic representations of therelative abundance of our top ten species list.
9/19/2002: Project development meeting
9/20/2002: Survey Bachelor Reserve
9/21-10/12: Research background information
10/13/2002: First Sample
11/1/2002: Second Sample
11/8/2002: Third Sample
11/9-12/5: Statistical analysis of data
12/7/2002: Complete Project
After our samples were sorted and classified into a generic species system wecompiled a list of the number of species and individuals per species.
With the data we calculated the percent relative abundance of each speciesand using this data we determined the species diversity and species richness ofeach scene (Table 2). Scene 1 had the highest diversity and richnessvalues, 3.16 and 7.43 respectively. Soy scene had the lowest values ofdiversity and richness, 1.83 and 2.61 respectivley.
Table 1: Diversity Indices of our study sites. Scene 1, the oldest ecological study site, had the highest diversity.
With the large amount of data we could not create a good graphicrepresentation of the percent relative abundance so we formulated a top tenrelative abundance graph. (Figure 1) Based on the recommendation made by Dr. Hays Cummins. We then used our "top ten" data and applied itto a Spearmen Rank test to determine any possible correlations betweenscenes. (Figures 2-4) Scene1 vs. Scene 4 showed a tied p-value of.0017 and a Rho value of -.43. Scene 1 vs. Soy Scene showed a tied p-valueof .6628. Scene 4 vs. Soy scene showed a tied p-value of .1526.
Figure 1:The Realtive Abundance of the Top Ten Species at each Scene. Click on the graph for a larger view.
Figure 2:The Relative Abundance of the Top Ten Species at Scene 1 vs Scene 4. Click on the graph for a larger view. Note that the results are significant--Scene 1 and Scene 4 are inversely correlated with one another. In other words, what is abundant in one scene is typically rare in the other scene.
Figure 3:The Relative Abundance of the Top Ten Species at Scene 4 vs Scene Soy. Click on the graph for a larger view. Note that the results are not significant--Scene 4 and Scene Soy have rank orders of abundance that are independent of each other.
Figure 4:The Relative Abundance of the Top Ten Species at Scene 1 vs Scene Soy. Click on the graph for a larger view. Note that the results are not significant--Scene 1 and Scene Soy have rank orders of abundance that are independent of each other.
Discussion and Conclusion
The results of our experiment show that Scene 1 and Scene 4have an inverse correlation and are not independent of each other. According to the Spearman Rank test a negative Rho value shows an inversecorrelation. Scene 1 contained an abundance of beetles and moths whileScene 4 contained an abundance of spiders. A p value less than .05 indicates indicatesthat we have to reject the null hypothesis and Scene 1 and Scene 4 are thereforenot independent of each other. Scene 1 and Scene 4 are very similar areasthat are not very far apart so it makes sense that these scenes would havesimilar species in them. A comparison between Scene 1 and Scene Soy showsthat they are independent of each other and do not have many similar species.With a tied p-value of .6628 we failed to reject the null hypothesis. Scene 4and Scene Soy were also independent of one another and do not have very manysimilar species. The tied p-value was .1526, again we failed to reject the nullhypothesis.
Our species diversity and species richness values support ourhypothesis that the older successional areas will have the most diversity.
Ourdata could have been effected by many variables. To begin, The periods at whichwe retrieved our sample were not correlated as well as they could have been. Forthe first sample the temperature was very warm and very dry. The second twosamples were both taken near the winter months after some light precipitationand once colder temperatures had set in. In regards to the Soy Scene, Our secondtwo samples were after the soy field had been harvested thus effecting theabundance of organisms there. During the sorting process we encountereddifficulty using the Burlese Funnels and resorted to sorting by hand. Thisprocess could have possibly reduced the number of organisms we found in oursampling. During the identification process, we found if difficult to classifythe different species and could have possibly miss identified some. The mostrelevant cause for miss identification was determining if certain organisms weremerely juvenile individuals of species we had already classified. It would havebeen particularly helpful to have worked with an entomologist. Instead wedevised our own classification scheme focusing primarily on the diversity ofinsects between each scene.
This experiment relates to biodiversity and theeffects of human impact on ecosystem diversity. It is evident from this studythat human impact severely decreases biodiversity. Could more professionalstudies similar in nature, when brought to public attention, influence therate at which humans are destroying natural ecosystems? It is our belief thatbiodiversity is essential to attain a healthy global environment. Our studycould be extended to other areas in Bachelor Reserve as well as any habitat nearan environment with human impact. More samples over a longer period of time willalso yield better results.
1. Kaufman, D. and C. Franz. 1996. Biosphere 2000. Kendall/Hunt Publishing
Co., Dubuque, Iowa.
This is our source of ecological terms and also reference.
2. Gramlich, Lori M. A Landscape Guide to the Bachelor Reserve.. 1998. Miami
This will serve as our guide to the Bachelor Reserve. It also has already
outlined the plant life and succession timeline for us.
3. Zimmerman, Deborah M. Examination of mechanisms of early old-field
succession in southwestern Ohio. 1983. Thesis (M. En.)--Miami University,
Institute of Environmental Sciences.
Provides an example of previous successional experiments.
4. Luken, James O. 1990. Directing Ecological Succession. Chapman and Hall,
New Dubuque, Iowa.
More on succession.
5. Geography Education Standards Project. 1994. Geography for Life, National
Geography Standards 1994. National Geographic Research and Exploration,
6. Molles, Manuel C., Ecology: Concepts and Application. McGraw-Hill. 2002.
7. Quammen, David. The Song of the Dodo. Touchstone. New York. 1996.
8. Siemann, Evan and Haarstad, John. "Insect Species Diversity,
Abundance, and Body-size Relationships." Nature. Apr. 1996. Vol 380: pp.
9. Kishbaugh, Michael and Yocom, Daniel. "The Impact of Habitat
Fragmentation of Arthropod Biodiversity. American Biology Teacher. June 2000.
Vol 62: pp. 414-420.
10. Tugel, A.J., A.M. Lewandowski, eds. (February 2001 -- last update). Soil
Biology Primer [online]. Available: www.statlab.iastate.edu/survey/SQI/soil_biology_primer.htm
11. Kogan, Marcos and Donald E. Kuhlman. Soybean
Insects. University of Illinois at Urbana-Champaign. 1982.
Anna. Color Handbook of Garden Insects. Rodale Press. Emmaus,
13. Cummins, Hays. Paleoecology Problem Set 2002.
Smithsonian Environmental Research Center
La Grande Forestry and Range Sciences Lab
Species 2000: Indexing the World's known Species
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