describe the 3 basic methods of ecological research

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• Ecology: Definition, Types, Importance & Examples

Ecological Research Methods: Observing, Experimenting & Modeling

Ecology is the study of the relationship between organisms and their environment on earth. Several ecological methods are used to study this relationship, including experimenting and modeling.

Manipulative, natural or observational experiments may be used. Modeling helps analyze the collected data.

What Is Ecology?

Ecology , the study of how organisms interact with their environment and each other, draws upon several other disciplines. The environmental science of ecology incorporates biology, chemistry, botany, zoology, mathematics and other fields.

Ecology examines species interactions, population size, ecological niches, food webs, energy flow and environmental factors. In order to do this, ecologists rely on careful methods to collect the most accurate data they can. Once data is collected, ecologists then analyze it for their research.

The information gained from these research methods can then help ecologists find impacts caused by humans or natural factors. This information can then be used to help manage and conserve impacted areas or species.

Observation and Field Work

Every experiment requires observation. Ecologists must observe the environment, the species within it and how those species interact, grow and change. Different research projects require different types of assessments and observations.

Ecologists sometimes use a desk-based assessment , or DBA, to collect and summarize information about specific areas of interest. In this scenario, ecologists are using information already collected from other sources.

Oftentimes, however, ecologists rely on observation and field work . This entails actually going into the habitat of the subject of interest to observe it in its natural state. By doing field surveys, ecologists can track population growth of species, observe community ecology in action and study the impact of any new species or other introduced phenomena in the environment.

Each field site will differ in nature, in shape or in other ways. Ecological methods allow for such differences so that different tools can be used for observations and sampling. It is crucial that sampling be done in a random fashion to combat bias.

Types of Data Obtained

Data obtained from observation and field work can be either qualitative or quantitative. These two classifications of data vary in distinct ways.

Qualitative data : Qualitative data refers to a quality of the subject or conditions . It is therefore a more descriptive form of data. It is not easily measured, and it is collected by observation.

Because qualitative data is descriptive, it might include aspects such as color, shape, whether the sky is cloudy or sunny, or other aspects for how an observation site might look. Qualitative data is not numerical like quantitative data. It is therefore considered less reliable than quantitative data.

Quantitative data: Quantitative data refers to numerical values or quantities . These kinds of data can be measured and are usually in number form. Examples of quantitative data might include pH levels in soil, the number of mice in a field site, sample data, salinity levels and other information in numeric form.

Ecologists use statistics to analyze quantitative data. It is therefore considered a more reliable form of data than qualitative data.

Types of Field Work Surveys

Direct survey: Scientists can directly observe animals and plants in their environment. This is called a direct survey. Even in places as remote as a seafloor, ecologist can study the underwater environment. A direct survey in this case would entail photographing or filming such an environment.

Some sampling methods used to record images of sea life on the seafloor include video sledges, water curtain cameras and Ham-Cams. Ham-Cams are attached to a Hamon Grab, a sample bucket device used to collect samples. This is one effective way to study animal populations.

The Hamon Grab is a method of collecting sediment from the seafloor, and the sediment is taken onto a boat for ecologists to sort through and photograph. These animals will be identified in a laboratory elsewhere.

In addition to a Hamon Grab, undersea collection devices include a beam trawl, which is used to obtain larger sea animals. This entails attaching a net to a steel beam and trawling from the back of a boat. The samples are brought on board the boat and photographed and counted.

Indirect survey: It is not always practical or desirable to observe organisms directly. In this situation, ecological methods entail observing the traces those species leave behind. These could include animal scat, footprints and other indicators of their presence.

Ecological Experiments

The overarching purpose of ecological methods for research is to get high-quality data. In order to do this, experiments must be carefully planned.

Hypothesis : The first step in any experimental design is to come up with a hypothesis or scientific question. Then, researchers can come up with a detailed plan for sampling.

Factors that affect field work experiments include the size and shape of an area that needs to be sampled. Field site sizes range from small to very large, depending on what ecological communities are being studied. Experiments in animal ecology must take into account potential movement and size of animals.

For example, spiders would not require a large field site for study. The same would be true when studying soil chemistry or soil invertebrates. You could use a size of 15 meters by 15 meters.

Herbaceous plants and small mammals might require field sites of up to 30 square meters. Trees and birds might need a couple of hectares. If you are studying large, mobile animals, such as deer or bears, this could mean needing a quite large area of several hectares.

Deciding upon the number of sites is also crucial. Some field studies might require only one site. But if two or more habitats are included in the study, two or more field sites are necessary.

Tools: Tools used for field sites include transects, sampling plots, plotless sampling, the point method, the transect-intercept method and the point-quarter method. The goal is to get unbiased samples of a high-enough quantity that statistical analyses will be sounder. Recording information on field data sheets aids in the data collection.

A well-designed ecological experiment will have a clear statement of purpose or question. Researchers should take extraordinary care to remove bias by providing both replication and randomization. Knowledge of the species being studied as well as the organisms within them is paramount.

Results: Upon completion, collected ecological data should be analyzed with a computer. There are three types of ecological experiments that can be made: manipulative, natural and observational.

Manipulative Experiments

Manipulative experiments are those in which the researcher alters a factor to see how it affects an ecosystem. It is possible to do this in the field or in a laboratory.

These kinds of experiments provide interference in a controlled manner. They work in cases in which field work cannot occur over an entire area, for various reasons.

The downside of manipulative experiments is they are not always representative of what would happen in the natural ecosystem. Additionally, manipulative experiments might not reveal the mechanism behind any patterns observed. It is also not easy to change variables in a manipulative experiment.

Example : If you wanted to learn about lizard predation of spiders, you could alter the number of lizards in enclosures and study how many spiders resulted from this effect.

A larger and current example of a manipulation experiment is the reintroduction of wolves into Yellowstone National Park. This reintroduction allows for ecologists to observe the effect of wolves returning to what was once their normal range.

Already, researchers have learned that an immediate change in the ecosystem occurred once wolves were reintroduced. Elk herd behaviors changed. Increased elk mortality led to a more stable food supply for both wolves and carrion eaters.

Natural Experiments

Natural experiments, as their name implies, are not directed by humans. These are manipulations of an ecosystem caused by nature. For example, in the wake of a natural disaster, climate change or invasive species introduction, the ecosystem itself represents an experiment.

Of course, real-world interactions such as these are not truly experiments. These scenarios do provide ecologists with opportunities to study the effects natural events have on species in an ecosystem.

Example: Ecologists could take a census of animals on an island to study their population density.

The main difference between manipulative and natural experiments from a data perspective is that natural experiments do not have controls. Therefore it is sometimes harder to determine cause and effect.

Nevertheless, there is useful information to be gained from natural experiments. Environmental variables like moisture levels and density of animals can still be used for data purposes. Additionally, natural experiments can occur across large areas or vast stretches of time. This further distinguishes them from manipulative experiments.

Unfortunately, humanity has caused catastrophic natural experiments across the globe. Some examples of these include habitat degradation, climate change, introduction of invasive species and removal of native species.

Observational Experiments

Observational experiments require adequate replications for high-quality data. The “rule of 10” applies here; researchers should collect 10 observations for each category required. Outside influences can still hamper efforts to collect data, such as weather and other disturbances. However, using 10 replicating observations can prove helpful for obtaining statistically significant data.

It is important to perform randomization, preferably prior to performing observational experiments. This can be done with a spreadsheet on a computer. Randomization strengthens data collection because it reduces bias.

Randomization and replication should be used together to be effective. Sites, samples and treatments should all be randomly assigned to avoid confounded results.

Ecological methods rely heavily on statistical and mathematical models. These provide ecologists with a way to predict how an ecosystem will change over time or react to changing conditions in the environment.

Modeling also provides another way to decipher ecological information when field work is not practical. In fact, there are several drawbacks to relying solely on field work.Because of the typically large scale of field work, it is not possible to replicate experiments exactly. Sometimes even the lifespan of organisms is a rate-limiting factor for field work. Other challenges include time, labor and space.

Modeling, therefore, provides a method in which to streamline information in a more efficient manner.

Examples of modeling include equations, simulations, graphs and statistical analyses. Ecologists use modeling for producing helpful maps as well. Modeling allows for calculations of data to fill in gaps from sampling. Without modeling, ecologists would be hampered by the sheer amount of data that needs to be analyzed and communicated. Computer modeling allows for comparatively rapid analysis of data.

A simulation model, for example, enables the description of systems that would otherwise be extremely difficult and too complex for traditional calculus. Modeling allows scientists to study coexistence, population dynamics and many other aspects of ecology. Modeling can help predict patterns for crucial planning purposes, such as for climate change.

Humanity’s impact upon the environment will continue. It therefore becomes ever more crucial for ecologists to use ecological research methods to find ways to mitigate the effects on the environment.

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• Wessex Archaeology: Explore the Seafloor: Ecological Research Methods
• EcologyandEvolution.org: How to Design a Field Study
• The University of Vermont: Designing Successful Field Studies
• MyYellowstonePark.com: Wolf Reintroduction Changes Ecosystem in Yellowstone
• Oxford Bibliographies: Simulation Modeling
• University of Ohio: Intro to Ecology and Experiments
• Clever ISM: Overview of Qualitative and Quantitative Data Collection Methods

About the Author

J. Dianne Dotson is a science writer with a degree in zoology/ecology and evolutionary biology. She spent nine years working in laboratory and clinical research. A lifelong writer, Dianne is also a content manager and science fiction and fantasy novelist. Dianne features science as well as writing topics on her website, jdiannedotson.com.

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Biology library

Course: biology library   >   unit 28.

• Ecology introduction

What is ecology?

• Ecological levels: from individuals to ecosystems
• Intro to ecology
• Ecology is the study of how organisms interact with one another and with their physical environment.
• The distribution and abundance of organisms on Earth is shaped by both biotic , living-organism-related, and abiotic , nonliving or physical, factors.
• Ecology is studied at many levels, including organism, population, community, ecosystem, and biosphere.

Welcome to ecology!

Biotic and abiotic factors.

• Maybe the mold needs a certain amount of water to grow, and this amount of water is found only in the shower. Water availability is an example of an abiotic , or nonliving, factor that can affect distribution of organisms.
• Maybe mold feeds off of dead skin cells found in the shower, but not in the dresser. Availability of nutrients provided by other organisms is an example of a biotic , living-organism-related, factor that can influence distribution.

Case study: the red panda

How do ecologists ask questions, ecology at many scales.

• Organism: Organismal ecologists study adaptations , beneficial features arising by natural selection, that allow organisms to live in specific habitats. These adaptations can be morphological, physiological, or behavioral.
• Population: A population is a group of organisms of the same species that live in the same area at the same time. Population ecologists study the size, density, and structure of populations and how they change over time.
• Community: A biological community consists of all the populations of different species that live in a given area. Community ecologists focus on interactions between populations and how these interactions shape the community.
• Ecosystem: An ecosystem consists of all the organisms in an area, the community, and the abiotic factors that influence that community. Ecosystem ecologists often focus on flow of energy and recycling of nutrients.
• Biosphere: The biosphere is planet Earth, viewed as an ecological system. Ecologists working at the biosphere level may study global patterns—for example, climate or species distribution—interactions among ecosystems, and phenomena that affect the entire globe, such as climate change.

Attribution

Works cited.

• "Red panda." World Wildlife Fund. Accessed June 7, 2016. http://www.worldwildlife.org/species/red-panda .
• A. Glatston, F. Wei, Than Zaw, and A. Sherpa, " Ailurus fulgens ." In The IUCN Red List of Threatened Species (2015): e.T714A45195924. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T714A45195924.en .
• Sean Breslin. "The Red Panda Could Become the Cutest Victim of Climate Change." The Weather Channel. August 19, 2015. https://weather.com/science/environment/news/red-panda-climate-change-fears .

Additional references

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1.4: Methods of ecology

• Last updated
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• Page ID 25417

• Clarence Lehman, Shelby Loberg, & Adam Clark
• University of Minnesota via University of Minnesota Libraries Publishing

How do ecologists do ecology? Often, they start with observation, then move to theory—trying to fit observations together to make sense as a whole. Theory then leads to expectations, which in turn lead to experiments. Commonly, experiments aren’t undertaken until there is some theory to be tested and understood.

• Observation
• Serendipity

Observation, theory, and experiment, however, are not the whole story. A large part of science turns out to be serendipity—luck and chance—capitalizing on chance and doing something with it. One example is Alexander Fleming, who discovered penicillin. Some of the bacterial cultures in his lab became contaminated with penicillium mold and the cultures died. That ruined his experiment.

He could have written a memo to the laboratory staff ordering “Always keep mold away from our bacterial cultures. It destroys the cultures and will ruin the hypotheses we are trying to test.” But instead he capitalized on the serendipity, wondered what was happening, and found a substance in penicillium mold that kills bacteria. Fungi and bacteria have been archenemies for perhaps a billion years. Fleming’s discovery has helped physicians actually cure disease, rather than being limited to diagnosing and prognosticating.

Following up on chance is, then, a large part of science. By the way, for an interesting paper, read the original 1929 report by Fleming about penicillium. It is so understated. He writes “the name ‘penicillin’ has been given to filtrates of broth cultures of the mould.” No one had heard of the word before. Then he suggests that “it may be an efficient antiseptic.” One of the greatest discoveries of all time and only, “it may be an efficient antiseptic.”

Cedar Creek is a University of Minnesota research site about thirty miles north of the University’s Saint Paul campus, and is one of the classic ecological research sites in the world. Pictured in Figure \(\PageIndex{1}\) is an experiment set up by Prof. David Tilman. While very carefully designed, it came about because of serendipity—the chance event of a deep two-year drought that altered the abundances of species in a particular way and triggered the idea for this experiment.

Keep your eyes open for such chance events; they can crop up anywhere.

Module 25: Ecology of Living Things

Levels of ecological research, learning outcomes.

• Define ecology and the four levels of ecological research

When a discipline such as biology is studied, it is often helpful to subdivide it into smaller, related areas. For instance, cell biologists interested in cell signaling need to understand the chemistry of the signal molecules (which are usually proteins) as well as the result of cell signaling. Ecologists interested in the factors that influence the survival of an endangered species might use mathematical models to predict how current conservation efforts affect endangered organisms.

To produce a sound set of management options, a  conservation biologist  needs to collect accurate data, including current population size, factors affecting reproduction (like physiology and behavior), habitat requirements (such as plants and soils), and potential human influences on the endangered population and its habitat (which might be derived through studies in sociology and urban ecology). Within the discipline of ecology, researchers work at four general levels, which sometimes overlap. These levels are organism, population, community, and ecosystem (Figure 1).

Figure 1. Ecologists study within several biological levels of organization. (credit “organisms”: modification of work by yeowatzup”/Flickr; credit “populations”: modification of work by “Crystl”/Flickr; credit “communities”: modification of work by US Fish and Wildlife Service; credit “ecosystems”: modification of work by Tom Carlisle, US Fish and Wildlife Service Headquarters; credit “biosphere”: NASA)

Organismal Ecology

Figure 2. The Karner blue butterfly (Lycaeides melissa samuelis) is a rare butterfly that lives only in open areas with few trees or shrubs, such as pine barrens and oak savannas. It can only lay its eggs on lupine plants. (credit: modification of work by J & K Hollingsworth, USFWS)

Researchers studying ecology at the organismal level are interested in the adaptations that enable individuals to live in specific habitats. These adaptations can be morphological, physiological, and behavioral. For instance, the Karner blue butterfly ( Lycaeides melissa samuelis ) (Figure 2) is considered a specialist because the females only  oviposit  (that is, lay eggs) on wild lupine ( Lupinus perennis ). This specific requirement and adaptation means that the Karner blue butterfly is completely dependent on the presence of wild lupine plants for its survival.After hatching, the (first instar) caterpillars emerge and spend four to six weeks feeding solely on wild lupine (Figure 3). The caterpillars pupate as a chrysalis to undergo the final stage of metamorphosis and emerge as butterflies after about four weeks. The adult butterflies feed on the nectar of flowers of wild lupine and other plant species, such as milkweeds. Generally there are two broods of the Karner blue each year.

A researcher interested in studying Karner blue butterflies at the organismal level might, in addition to asking questions about egg laying requirements, ask questions about the butterflies’ preferred thoracic flight temperature (a physiological question), or the behavior of the caterpillars when they are at different larval stages (a behavioral question).

Figure 3. The wild lupine (Lupinus perennis) is the only known host plant for the Karner blue butterfly.

Population Ecology

A  population  is a group of  interbreeding organisms  that are members of the same species living in the same area at the same time. (Organisms that are all members of the same species are called  conspecifics .) A population is identified, in part, by where it lives, and its area of population may have natural or artificial boundaries. Natural boundaries might be rivers, mountains, or deserts, while artificial boundaries may be mowed grass, manmade structures, or roads. The study of  population ecology  focuses on the number of individuals in an area and how and why population size changes over time.

For example, population ecologists are particularly interested in counting the Karner blue butterfly because it is classified as a federally endangered species. However, the distribution and density of this species is highly influenced by the distribution and abundance of wild lupine, and the biophysical environment around it. Researchers might ask questions about the factors leading to the decline of wild lupine and how these affect Karner blue butterflies. For example, ecologists know that wild lupine thrives in open areas where trees and shrubs are largely absent. In natural settings, intermittent wildfires regularly remove trees and shrubs, helping to maintain the open areas that wild lupine requires. Mathematical models can be used to understand how wildfire suppression by humans has led to the decline of this important plant for the Karner blue butterfly.

Community Ecology

A  biological community  consists of the different species within an area, typically a three-dimensional space, and the interactions within and among these species. Community ecologists are interested in the processes driving these interactions and their consequences. Questions about  conspecific  interactions often focus on competition among members of the same species for a limited resource. Ecologists also study interactions between various species; members of different species are called  heterospecifics . Examples of heterospecific interactions include predation, parasitism, herbivory, competition, and pollination. These interactions can have regulating effects on population sizes and can impact ecological and evolutionary processes affecting diversity.

For example, Karner blue butterfly larvae form mutualistic relationships with ants (especially  Formica  spp).  Mutualism  is a form of long-term relationship that has coevolved between two species and from which each species benefits. For mutualism to exist between individual organisms, each species must receive  some  benefit from the other as a consequence of the relationship. Researchers have shown that there is an increase in survival when ants protect Karner blue butterfly larvae (caterpillars) from predaceous insects and spiders, an act known as “tending.” This might be because the larvae spend less time in each life stage when tended by ants, which provides an advantage for the larvae. Meanwhile, to attract the ants, the Karner blue butterfly larvae secrete ant-like pheromones and a carbohydrate-rich substance that is an important energy source for the ants. Both the Karner blue larvae and the ants benefit from their interaction, although the species of attendant ants may be partially opportunistic and vary over the range of the butterfly.

Ecosystem Ecology

Ecosystem ecology  is an extension of organismal, population, and community ecology. The ecosystem is composed of all the  biotic  components (living things) in an area along with the  abiotic  components (nonliving things) of that area. Some of the abiotic components include air, water, and soil. Ecosystem biologists ask questions about how nutrients and energy are stored and how they move among organisms and through the surrounding atmosphere, soil, and water.

The Karner blue butterflies and the wild lupine live in an oak-pine barren habitat. This habitat is characterized by natural disturbance and nutrient-poor soils that are low in nitrogen. The availability of nutrients is an important factor in the distribution of the plants that live in this habitat. Researchers interested in ecosystem ecology could ask questions about the importance of limited resources and the movement of resources, such as nutrients, though the biotic and abiotic portions of the ecosystem.

Watch this video for another introduction to ecology:

Dividing Ecological Study

Ecology can also be classified on the basis of:

• the primary kinds of organism under study (e.g. animal ecology, plant ecology, insect ecology)
• the biomes principally studied (e.g. forest ecology, grassland ecology, desert ecology, benthic ecology, marine ecology, urban ecology)
• the geographic or climatic area (e.g. arctic ecology, tropical ecology)
• the spatial scale under consideration (e.g. macroecology, landscape ecology)
• the philosophical approach (e.g. systems ecology which adopts a holistic approach)
• the methods used (e.g. molecular ecology)
• Biology 2e. Provided by : OpenStax. Located at : http://cnx.org/contents/[email protected] . License : CC BY: Attribution . License Terms : Access for free at https://openstax.org/books/biology-2e/pages/1-introduction
• Ecology (disciplines). Provided by : Wikipedia. Located at : https://en.wikipedia.org/wiki/Ecology_(disciplines) . License : CC BY-SA: Attribution-ShareAlike