Experimentation

How are experiments central to ecology?
Science attempts to provide the best possible picture of what is going on behind the phenomena. It describes the unseen components of the problem. Theories are the accounts of the underlying composition or unseen causes; they speak about things beyond the evidence.<!--break--> Classical scientific methods include hypothesis forming and testing to resolve scientific questions and build theories. A hypothesis might be tested repeatedly and thus evolve into a theory. Generating and testing hypotheses provides important practice in risk taking and divergent thinking. Ecological experiments are used frequently by ecologists to answer both theoretical and applied questions (for example, see the article by Eberhardt and Thomas).

Experiments in ecology follow the logical pattern of deductive reasoning used in other scientific fields. Although many science teachers have their students collect data without using experimental techniques (called "mensurative" experiments, the majority of ecologists consider that only manipulative experiments, when you assign treatments and controls and where replication of each treatment plot are used, to be preferable. An experimental approach is better for producing credible, reliable scientific data that can withstand peer review and guide natural resource management.

There are 5 key features of science research as a mode of inquiry (AAAS, 1989):

1. The process of forming and testing hypotheses
2. Developing an experimental design
3. Obtaining evidence by observation and measurement
4. Using logic and insight to analyze data
5. Developing an explanation based on valid observations using logic and application of conceptual knowledge

1- Process of forming and testing a hypothesis. Why do you need a hypothesis? Questions are the basic of inquiry; without a hypothesis, you don’t have a framework to test your data. A research question asks: "What relation exists between two or more variables?" It expresses a possible, clearly stated relation between these variables, and the question implies possibilities for an experiment to test the relationship. Research questions are often stated as predictions of a relation between two or more variables. Predictions are synonymous with hypotheses since you must have some sort of expectation of an outcome or result when you form a hypothesis. This also implies that you already know something about the ecosystem, the particular site and the existing conditions there.

There are a wide range of questions that you might investigate as ecologists. Overall questions include: What factors determine the abundance of species? How important are particular interactions between species? Question investigated in plant ecology, for example, focuses on the patterns, causes, and consequences of plant abundance and/or distribution in nature. Once you have your research topic and overarching purpose, such as an investigation of nearby forest, clearly in mind, you can start framing your research questions and generate a simple model of the important factors you think directly affect the subject. The factors affecting species abundance and distribution fall into two broad categories: abiotic and biotic causes or variables. Abiotic factors are any variable in the environment that is not living. These abiotic factors include, but are not limited to, light intensity, temperature, variation in temperature, length of growing season, fire regimes, soil moisture, soil nutrient availability, rain fall, and seasonal variation in rain fall. Biotic factors are any variable in the environment that is created by another living organism. Biotic factors include, but are not limited to, competition, herbivory, mutualism, and disease. The basis for your research hypotheses will be about relationships between 2 or more of these variables and individuals, populations, or communities.

The process of forming a clear hypothesis and devising acceptable tests is called "strong inference". It is described in a famous paper by Platt. Click here to read: Strong Inference. In the paper, Platt also describes why you should devise alternative hypotheses.

Try developing several questions related to your topic, and then choose one that best fits. Rephrase your question until it is both analytical, requiring analysis of data, and focused and based upon previous information on the topic to prevent a superficial discussion.
How do ecological theories help shape your hypothesis?