Ecological Methods

Abstract

Ecological methods cover a wide range of techniques required for studies that range in scale from the individuals on a single flower head to entire ecosystems with thousands of species. Although both the scale and the questions a study is designed to answer can vary greatly, there are certain key components that are always present in a well‚Äźdesigned ecological study. First, ecological studies involve setting objectives and formulating a sampling programme. Second, there is often a practical component involving measurement and sampling in the field, which frequently includes sorting, identifying and measuring the organisms retrieved. Third, there is data analysis and reporting. The results can be used to derive absolute or relative population abundance measures, construct life tables, probe population dynamics and estimate biodiversity.

Key Concepts:

  • Ecological methods address a wide range of scales and are concerned with the acquisition of data on individual organisms, single populations and entire ecosystems.

  • Ecological studies have three key components: programme planning, field data acquisition and data analysis.

  • Studies can be broadly classified as intensive or extensive. Extensive studies are carried out over larger areas than intensive studies and seek to obtain information on the distribution and abundance of species for conservation and management purposes. Intensive studies involve the repeated observation of a population to gain insight into demographic processes.

  • Sampling methods can be classified into absolute methods, which give densities per unit area of habitat and relative measures which give an index of abundance.

Keywords: populations; community; ecology; sampling methods; diversity

Figure 1.

A typical wire quadrate sampler used in ecology to define an area within which plants or animals are counted.

Figure 2.

A point sampler used by botanists to calculate a measure of ground cover by different plants.

Figure 3.

A range of sampling nets used in freshwater ecology. The picture shows a hand net, a plankton net and a kick sampling net.

Figure 4.

A typical benthic grab sampler used in marine ecology to collect samples of sediment and the animals from the sea bed.

Figure 5.

Core samplers, used to collect samples of soil or soft sediment.

Figure 6.

A typical pitfall trap used to sample insects and spiders. The trap is a disposable cup covered by a sheet of plastic to stop the trap becoming flooded by rain water.

Figure 7.

A portable light trap used mainly to sample night‐flying insects such as moths.

Figure 8.

A malaise trap used to catch day‐flying insects.

Figure 9.

A gill net deployed on a beach. The fish become entangled when the net is covered by the tide and are recovered at low water.

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References

Bray JR and Curtis CT (1957) An ordination of the upland forest communities of southern Wisconsin. Ecological Monographs 27: 325–349.

Henderson PA (2002) Practical Methods in Ecology. Oxford: Blackwell Scientific.

Krebs CJ (1999) Ecological Methodology, 2nd edn. Menlo Park, CA: Longman.

Legendre P and Legendre L (1998) Numerical Ecology. Amsterdam: Elsevier.

Southwood TRE and Henderson PA (2000) Ecological Methods, 3rd edn. Oxford: Blackwell Science.

Further Reading

Dent DR and Walton MP (eds) (1997) Methods in Ecological and Agricultural Entomology. New York: CAB International.

Fowler J, Cohen L and Jarvis P (1998) Practical Statistics for Field Biology, 2nd edn. New York: Wiley.

Magurran AE (2004) Measuring Biological Diversity. Oxford: Blackwell Publishing.

New TR (1998) Invertebrate Surveys for Conservation. Oxford: Oxford University Press.

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How to Cite close
Henderson, Peter Alan(May 2012) Ecological Methods. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003271.pub2]