Planning an Investigation, Communicating Science, Ecological Indices 1

Planning an Investigation, Communicating Science, Ecological Indices 1

PLANNING AN ECOLOGICAL INVESTIGATION

I. Planning an Investigation

Below are listed some guidelines that may be helpful to you when you are planning an investigation.

A. Decide which question(s) should be investigated.

Questions are usually based on previous observations or experiences, and on your thoughts and ideas.

Choose a question (or topic) that you are interested in and that you see as worth investigating.

Discuss you ideas with other people. They may help you view things from a different perspective and improve or add to your ideas. Once you have chosen a question, try to explain it to a friend. This may help you clarify your idea of your question and which methods you need to use to answer it.

B. Reduce the question to a manageable size.

Can you break the question into smaller questions? If so, list these sub-questions on a sheet of paper (or in a data book). Try to list all the questions that will have to be answered in order to answer your original question. Then decide which questions are most important and can be properly addressed given the time and resources available.

C. Identify assumptions in the question(s) you have decided to investigate.

What assumptions are you making? Are they valid (i.e., based on accepted information), or should they be tested?

Consider the following examples:

"Why aren't people as concerned about pollution as they used to be?" or

"Why do seeds require light to germinate?"

Do you recognize the assumptions in these examples? If you are unsure, cover up the word "why'" and read the questions again. Questions that begin with why, what, when, where, or how often include important assumptions that may themselves need verifying or testing. Of course, not all assumptions need to be tested if the investigator can be reasonably sure that they are valid.

D. Turn your questions into hypotheses.

In its simplest form, a hypothesis can be viewed as an educated guess. Hypotheses are statements made from questions that can be falsified. Thus, if you can state the question in such a way that it can be answered yes or no, it can be readily turned into a hypothesis. Try to make your hypothesis as specific as possible. Testable hypotheses are more specific statements that may include what, when, where, or how you are going to measure some variable related to your hypothesis.

Question with an assumption: "How does fire affect grazing patterns of bison?"

Restated without an assumption: "Does fire affect grazing patterns of bison?"

Hypothesis: "Fire affects grazing patterns of bison."

Example:

Testable hypothesis: "The bison herd on Konza Prairie will spend more time grazing in watersheds burned the prior spring than in watersheds not burned for 2 or more years."

II. Ideas for Independent Field/Lab Projects

In general, you may want to test for relationships between an organism/system characteristic and site/environmental variables. Examples of different organism/system characteristics and site/environmental variables are listed in Table 1. Refer to the Ecological Indices and Sampling Lab for more information about measuring different these and other characteristics and variables.

Table.1. Examples of different organism/system characteristics and site/environmental variables that could be used to develop hypotheses.

Organism/System Characteristic / Site/Environmental Variables
height, width, length / slope
diameter, growth rate / aspect
species composition / elevation
biomass / soil moisture
litter depth, litter mass / air temperature
decomposition rate / nutrient availability
density, frequency / community type
seed viability / substrate type, location
fecundity, reproductive effort / light availability
species diversity, richness / disturbance type, size
behavior / resource availability
water loss, use / stream velocity
fur color, scale size / water depth, temperature
nutrient concentration / habitat structure
age, species / windspeed

Examples:

a) Relationship between litter depth and aspect.

Hypothesis: Litter depth will be greater on north and east facing slopes than south and west facing slopes in tallgrass prairie.

b) Relationship between growth rate and temperature.

Hypothesis: King snakes will exhibit greater growth rates, as measured by mass increase, when kept at 30C vs. 20C.

c) Relationship between growth rate and light availability.

Hypothesis: Juniper trees will exhibit greater growth rates, as measured by the width of growth rings in trunks, in sites with higher light availability (i.e., prairie) than understory sites.

COMMUNICATING SCIENCE

I. Scientific Writing

A. Introduction

The ability to write a concise, well-organized, and logical paper is a necessary skill for anyone planning a career in any professional field. Effective communication of information and ideas is as important as the collection, analysis, and interpretation of data.

There are some general rules to guide the preparation of scientific papers but developing style requires, above all else, practice (including editing and revision). Papers should not only follow the rules but should also incorporate elements of style (defined as "proper words in proper places" by Swift). Thus, a paper may be technically correct but be difficult and boring to read. Exposure to scientific literature will help you begin to develop your own scientific writing skills.

You should not expect to write a perfect paper on the first try. Every scientist, no matter how accomplished, revises manuscripts many times. Although we do not expect you to turn in papers for this class with all the elements of style found in published papers, you will be expected to follow the rules of scientific writing.

B. Format of Scientific Papers

The purpose of a scientific paper is to convey the details of an experiment or study in a logical, concise and unambiguous manner. For this class, all reports should contain the following sections: Introduction, Materials and Methods, Results, Discussion, and Literature Cited. Before writing, construct an outline to organize all your ideas. This will help you organize your thoughts and provides a guideline for writing concisely and comprehensibly. The outline can be either a topic outline (headings, keywords) or a sentence outline (uses main topic sentences). While writing, use your outline as a guide but remember you can modify the outline as you work.

1. Introduction

The Introduction is a statement of the objectives of the investigation with relevant background material. The main questions it addresses are: Why did you do the work (scientific justification not personal justification)? What is its purpose? The introduction should include any hypotheses tested and a concise (brief) statement of what you did including the variable(s) measured.

2. Materials and Methods

The Materials and Methods gives a description of how, where, and when the study or experiment was conducted. This section should address the following: 1) Where the project was conducted (i.e., study site(s)), 2) When the project was conducted, and 3) How and when sampling occurred. Specifically, it describes how you measured variables in a logical order. Since the goal of this section is to give sufficient information for the study to be repeated by other researchers, it is best to err on the side of too much detail but avoid stating the obvious (e.g., you need not state that the balance was turned on prior to weighing samples). However, there is a fine line between too much and too little detail.

3. Results

The Results is a summary and analysis of the data collected and should answer the question: What was found? Present your results in a logical order using tables or figures to support the written portion. Use the following guidelines when writing your results:

a)Use tables and/or figures when they can summarize data. Tables and figures should be interpretable by themselves without having to refer to the text. Always include captions and labels.

b)Do not repeat the table titles and figure legends in the text or use them as topic sentences for paragraphs. For example, write 'A had lower cover than B in the grazed treatment (Fig. 1)', instead of 'The cover of A and B in the grazed treatment is shown in Figure 1'.

c)Do not repeat data in tables if you plan to put the same data in the text or a figure.

d)Use concise text that leads the reader through the data and points out the important features.

e)Statistical results should be included in the tables/figure, if appropriate, or in the text.

f)This section should not contain 'discussion' of the data or 'raw data', except in specialized cases.

Tables and Figures

In general, tables are better for reporting precise numerical information, whereas graphs are better for illustrating trends and relationships among variables, and for numerous numerical results.

Types and use of figures:

a)Scatterplots - used to show a relationship between two variables (Fig.1A).

b)Line graphs - used for showing a response variable over time (Fig.1B). Position the dependent variable on the y-axis and the independent variable on the x-axis.

c)Bar graphs - used when there is no evidence of a continuum between data points (you have discrete categories) or when findings can be sub-divided and compared in different ways (Fig.1C).

d)Histogram - used to show frequency distribution of observations (Fig. 1D)

e)Pie charts - used when comparing sizes of component parts

Table and figure legends should state the point of the table or figure and which items it compares. They should be complete enough to stand alone from the main text (often readers only look at tables and figures). Information about the experimental design can be included.

4. Discussion

The Discussion is your interpretation of the results of the study, their significance, and their place in the context of other studies. With this section, you should answer the general question: What do your findings mean and how do they contribute to the body of scientific knowledge? Also, the discussion is where you answer the specific question(s) you stated in the Introduction. Do not repeat your results here, but instead discuss their importance and relevance to your objectives/hypotheses stated in the introduction. This section has the most leeway in format, and you decide what points should be emphasized.

5. Literature Cited

Background information that you include in the text should have its source cited in this section. Refer to a recent issue of the journal Ecology for the proper format. Always double-check your citations! This is one of the most important parts of a paper and often has the most mistakes.

C. Helpful Hints

1. The first person, active voice (I, we) is usually preferred and is most efficient.

1. Simple past tense is always used except when reference is made to stable conditions or generalizations in the present time. For example, to distinguish between results and the conclusions you are drawing from them, use the past tense for results and the present tense for general statements and conclusion.

1. Tables and figures should appear in the order you discuss them in the results section, and each table or figure should be numbered consecutively (e.g., Table 1, Table 2, ....Figure 1, Figure 2...). Do not mix the numbering of tables and figures.

1. Cite each table and figure at least once in the text.

1. Be succinct. Avoid repetition and unnecessary words, phrases, and paragraphs.

1. Use numbers before any standard unit of measure and for any number larger than nine.

1. Always begin a paragraph with a topic sentence. Each sentence within a paragraph should relate to the previous sentence using appropriate transitions. Sentences that do not relate to the topic sentence should be placed in a different paragraph.

1. Select one name for organisms, techniques, and equipment mentioned and use the names throughout the paper. Use full scientific names (i.e., genus species) the first time you reference an organism.

1. Avoid paragraphs that are consistently too short or too long. Three paragraphs per double-spaced page is typical for most scientific writing.

II. Presenting a Short Talk

Although communicating research results is most efficient in a scientific manuscript, an oral presentation of results is more timely and can provide immediate feedback from the scientific community. Most scientists present their research results regularly at regional, national or international conferences and this is often an important first step in producing a journal article.

For this class, you will give a 5-10 minute presentation of findings from your independent project. For the presentation, you will need a minimum of 6 overheads (Microsoft PowerPoint slides are preferred) that include the following information:

1. Title of talk and name of investigators
2. Brief background and justification for research (why is this important or interesting?)
3. A statement of your testable hypothesis
4. Brief methods (what, where and how)
5. Results (1 or more graphs, tables, or bullet statements)
6. Conclusions relating back to your hypothesis and a brief discussion/explanation of your results

You certainly may have more than 6 slides, above are minimum requirements.

You must turn in threepaper copies of an abstract of your talk to your instructor before giving your presentation.

Helpful Hints

Make a written draft or an outline of your talk and practice (as many times as possible) so that you will not have to rely on notes extensively during your talk. Practice will also allow you to stay within the allotted time.

Make sure you face the audience while talking. If you need to draw attention to a particular part of a slide, point to the screen with a laser pointer or stick and either raise your voice or turn towards the audience to make sure you can be heard.

ECOLOGICAL INDICES AND SAMPLING TECHNIQUES

Ecological indices and parameters have been designed to help ecologists describe organisms and to understand the interactions between an organism with its environment. Ecological sampling techniques are designed to measure a characteristic of a population, community, or ecosystem on a small scale so that inferences can be made about the much larger system from which the samples were drawn. A quick overview of different ecological indices and sampling techniques are provided below. Refer to Brower et al. (1998) and Magurran (1988) for more detailed information.

I. Ecological Indices

1. Population ecology – study of environmental effects on populations

1. Population structure

a)Density – number of individuals per unit area

b)Frequency – number of times a given event/organism occurs

c)Dominance – total species cover per unit area

d)Biomass – total weight per unit area

e)Importance – relative density + relative dominance + relative frequency

2. Population dynamics

a)Dispersion – uniform, random, contagious; Poisson (normal) distribution

b)Coefficient of similarity – comparison of structure of two or more communities

c)Age/size structure – number per age/size group

d)Life history patterns – mortality, natality, survivorship, life tables

e)Competition – intraspecific (between individuals of the same species), interspecific (between individuals of different species)

f)Behavior

1)animals – time budgets, diet, movement, spacing, reproductive effort and mating strategies

2)plants – energy budget, growth form, reproductive effort, sexual vs. asexual reproduction

1. Community Ecology – study of communities, which are assemblages of interacting populations

1. Community structure

a)Growth/life forms – plants: perennial, biennial, annual or grass, forb, etc.

b)Distribution – vertical, horizontal

c)Richness, diversity, evenness

1)Richness – total number of species

2)Species diversity – incorporates both the number of species and the distribution of individuals among the different species

Information-theoretic indices – related to the concept of uncertainty

Shannon diversity index (H):

H = -  [pi*ln(pi)]or = [N*ln(N) -  (ni*ln(ni))]/N

wherepi = proportion of the total number of individuals that belong to species i

N = total abundance

ni = abundance of species i

ln = natural log

3)Evenness (J) - distribution of individuals among species

J = H / Hmax

whereH = Shannon diversity index

Hmax = ln(S)

1. Community dynamics

a)Relationships within a community

1)Species association – like population dispersion but between several species

2)Lotka-Volterra equations – used to describe interspecific competition

b)Relationships among communities

1) Coefficient of similarity

2) Comparison of species diversity – an expression of community structure

II. Ecological Sampling Techniques

1. Plant sampling

1)Plot/quadrat sampling

2)Transect sampling (belt or line-intercept)

3)Point-quarter sampling – a number of randomly-determined points are selected within an area and the nearest plant in each of four quadrants around each point is identified and measured.

1. Animal sampling

Animal sampling is often more difficult than plant sampling simply because animals are more mobile. Thus, many animal sampling techniques often involve some sort of trapping method. Trap type and placement requires the researcher to have a general knowledge of the behavioral patterns of the organism to be trapped. Both removal sampling and capture-recapture techniques are widely used.

1)Ground microinvertebrates (< 2 mm)

- Berlese-Tullgren funnel – heat source drives animals down through soil into funnel

2)Ground macroinvertebrates (> 2 mm)

- species analysis of known volume of soil

3)Mobile litter-inhabiting macroinvertebrates

a)Pitfall traps – container buried with rim flush with soil surface used to collect/kill invertebrates over a given period of time

b)Sticky traps – sticky substrate such as fly paper used to collect/kill invertebrates

4)Vegetative macroinvertebrates

a)Sweep nets – works best in light shrubs and grasslands

b)Catch traps – trees or shrubs are shaken or fumigated causing organisms to fall onto collecting cloths

c)Scent traps – pheromones or food used as bait

d)Light traps – best for nocturnal flying insects

5)Vertebrates

a)Pitfall traps – used for small mammals and herptiles