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LS1114 Principles of Biology Fall 2005 Winslow

Guidelines and helpful hints for writing research report on tree communities

This paper is due on 9 December and is worth 50 points. It might be 5 or 10 pages long, including tables and figures and references.

The objective of this exercise is to write about the tree community at the Shawnee Conservation District Outdoor Learning Center. You will write the paper in the format of a scientific research report.

A scientific research report typically includes a title page, an abstract, an introduction, a methods section, a results section, a discussion section, and a reference section. The best way to learn about this structure is to read papers published in peer-reviewed scientific journals, which you will want to do anyway to research your topic.

The Title

The title of a scientific paper states the specific question or topic under study. Oftentimes the study addresses the effect of one factor on another. For instance, one paper published in a recent issue of Conservation Biology is entitled "Effects of forest fragmentation on a dung beetle community in French Guiana" (Feer and Hingrat, 2005). The title may also be phrased as a question. The title page should state the title, your name, the date, and your institution (St. Gregory's University).

The Abstract

The abstract concisely summarizes everything in the main body of the paper. It may be easiest to write this section last. You should be able to decompose an abstract to find sentences corresponding to the introduction, methods, results, and discussion sections. You may read many published abstracts in the course of looking for appropriate sources for your paper. Often abstracts are available for free online, but the full-length paper may be more difficult to obtain.

The Introduction

The introduction section gives background information for the topic, citing relevant literature. It should also state the objectives for the study and any questions that are being addressed. Look for some general sources that will give you basic information on the natural history of the tree species you are studying and the effects of landscape features (such as the presence of a creek or habitat edge) on tree community composition. Also find some relevant articles from peer-reviewed journals.

Scientific names of tree species should be included in parentheses after common names when the common names are mentioned in the text. The tree species we observed are listed in an Appendix at the end of this document. Notice that scientific names of species are italicized, the genus name beginning with a capital letter and the specific epithet all lower-case. Bear in mind that we may have made some misidentifications, so some of these species may not actually be present at this site.

For general sources, look for books in the St. Gregory's University library. You can search the database at: http://intranet.stgregorys.edu/places/library/ (click on "SOULS online catalog"). For peer-reviewed journals, click on "find journal articles" and then "EBSCOhost Web". Try searching for articles using the name (common and/or scientific) of the species you are studying. You are also welcome to peruse the books and journals on my bookshelf.

Notice how I am citing the paper by Feer and Hingrat (2005) in this document. That is how you should cite sources, referring to them by author and date in the text of your paper and listing them in a section titled "Literature cited" or "References" or "Bibliography" at the end. Look at published journal articles to become familiar with this format. Pay particular attention to the information which is included in each listed reference in the bibliography.

Please refer to the class syllabus to be sure you understand what plagiarism is and how to avoid it. In general you should write in your own words, paraphrasing the findings of the authors you cite. If you do include a quote by another author, be sure to enclose it in quotation marks or indent it to indicate it is a quote. Be sure to give the full reference for any quoted passages.

The last paragraph of the introduction should state the objectives of the study. One general goal of our study is to characterize the tree species composition of the Outdoor Learning Center. Clearly phrase any questions you are attempting to answer. Also state any hypotheses to be tested. Generally speaking, we are interested in determining the effects of landscape features on tree community composition. Consider some more specific questions you can ask with our data set, considering specific landscape features and aspects of tree communities (e.g. species richness, species diversity, the relative abundance of cedars, the basal area of sugarberry, etc).

The Methods section

After the introduction to a scientific paper comes a section titled "Methods" or "Methods and Materials". This section describes what the investigators did in sufficient detail that another researcher in the same field could replicate it. So describe where you went, what you did, what sort of observations you made. Keep in mind that the methods you used should be relevant to the questions posed in the Introduction. With field studies, there is often a map included as the first figure. Be sure to cite the source of any images you use.

Most scientific papers include several figures and tables. The authors refer to these figures and tables by number in the text as the information is discussed. Each figure or table has a caption which describes in a few sentences the information contained. Look at some examples in published papers or in your biology textbook (Mader, 2004) to see how this is done. A table will have headings for each column and possibly footnotes.

Most of the tables and figures in a scientific paper are associated with the Results section.

The Results section

After the Methods section is a section titled "Results". The text of the Results section describes the findings from the study, often using summary statistics and inferential statistics to analyze the data. Describe what you observed, summarizing quantitative information with statistics, tables, and figures.

Summary statistics you may use would include community attributes (such as species diversity and species richness) and the attributes of individual species (such as relative abundance and basal area). You may calculate these indices for the entire data set, but you may also be interested in describing how an index varies with respect to a given habitat feature.

To calculate relative abundance of a tree species, divide the number of individuals of that species by the total number of trees of all species. The sum of the relative abundances of all species is 1.

There are several indices of species diversity; one of the most widely used is the Shannon-Wiener index (Molles, 2005). The Shannon-Wiener index is calculated as:

H' = -∑pi ln pi,

where pi is the relative abundance of each species i and ln pi is the natural logarithm of pi. That is, multiply the relative abundance of each species by the natural log of its relative abundance, add these products across all species, and then change the sign from negative to positive.

The species richness is simply the number of species observed.

Basal area of a given species is calculated by summing the estimated cross-sectional areas of each trunk for that species. The cross-sectional area of a given tree is estimated by dividing the measured diameter by 2 to obtain the radius, squaring the radius, and then multiplying that number by π. Because we measured diameter in centimeters and basal area is commonly expressed in meters squared, you will want to divide the resulting value by 10000 cm2/ m2.

In addition to describing findings in the text of the Results section, data are presented in tables and figures. Most of the figures in a scientific paper tend to be graphs, showing relationships among variables measured. The variables in our case are the distances from habitat features and attributes of tree species and the tree species community. Bear in mind that the observations you describe in the Results section should address the questions posed in the Introduction.

We measured 30 m between each successive sampling point, so we have a rough estimate of the distance from each habitat type. Because we did not consistently measure the bearing (i.e. compass direction) between each point, we cannot calculate exact distances.
It may also be useful to calculate some traditional sampling statistics. For instance, if you are interested in knowing which species tends to be larger, you might calculate the mean (average) diameter of each species. Because variation is just as important as central tendency, the minimum and maximum diameters may also be of interest.

The Discussion section

The Discussion section ties everything together, answering the questions posed in the Introduction. While the Results section objectively states the facts, the Discussion section uses inference to draw conclusions about the phenomena under study. Oftentimes this involves generalizing from the specific sample studied to a larger population of interest, or from specific mechanisms to more general processes. The Discussion also should consider the limitations of the study in addressing the questions of interest, compare findings with those of other similar studies, and make suggestions for future research directions. The Discussion section is also the appropriate place to make recommendations for policy. For instance, a natural history paper might make suggestions for management of forests or other natural resources.

The Reference section

The Bibliography should include all references cited in the text and in the captions of tables and figures. No other references should be included. A book citation should include the authors or editors, year published, title, publishing company, and the city where it was published. A citation of a journal article should include the authors, year published, title of the paper, title of the journal, volume number, and page numbers. For sources accessed from the internet, include the authors, year published, date accessed by you, title, the name of the institution sponsoring the website, and the web address (uniform resource locator). Look in published papers for examples of how to list other types of documents.


Appendix
Common and scientific names of tree species observed at the Outdoor Classroom in the fall of 2005.

Eastern Redcedar Juniperus virginiana
Oriental Arborvitae Thuja orientalis
Eastern Cottonwood Populus deltoides
Pecan Carya illinoensis
Blackjack Oak Quercus marilandica
Chinkapin Oak Quercus muehlenbergii
Post Oak Quercus stellata
Sugarberry Celtis laevigata
Hackberry Celtis occidentalis
Winged Elm Ulmus alata
American Elm Ulmus Americana
Slippery Elm Ulmus rubra
Paper-mulberry Broussonetia papyrifera
Sycamore Platanus occidentalis
Hortulan Plum Prunus hortulana
Yellowwood Cladrastis kentukea
Chittamwood Bumelia lanuginose
Common Persimmon Diospyros virginiana
Northern Catalpa Catalpa speciosa

Literature cited

Feer, François, and Yves Hungrat. 2005. Effects of forest fragmentation on a dung beetle community in French Guiana. Conservation Biology 19:1103-1112.

Mader, Sylvia S. 2004. Biology, 8th Ed. McGraw-Hill, NY.

Molles, Manuel C., Jr. 2005. Ecology: Concepts and Applications, 3rd Ed. McGraw-Hill, NY, pp. 401-402.

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