2 - Sampling methods

Summary

Community sampling is the initial, observational phase of community studies. The inherent strength or weakness of a study and the range of potential data analyses that will be subsequently appropriate are determined and fixed to a great degree at this first step, data collection (Cain & Castro 1959:2; Poore 1962; Greig-Smith 1964:20; Mueller- Dombois & Ellenberg 1974:32). An investigator planning a sampling procedure faces three questions, which will be considered in detail in the following three sections. (1) What general considerations and tradeoffs affect the practicality and effectiveness of sampling procedures? (2) What community sampling procedure is best for a particular study? (3) What corroborative environmental and historical data should be gathered at each sample site?

The first question involves general principles, which can be treated reasonably well in this chapter. They will be discussed primarily in the context of terrestrial vascular plants, but other kinds of communities will be discussed later in this chapter. The second and third questions involve so many permutations of research purpose, level of accuracy, scope of study, kind or kinds of communities, intended subsequent analysis, and so on, that thorough treatment here is impractical. Thus, for these questions, only a sketchy response will be offered, with the burden carried by references to the literature. This is fair enough because an investigator planning a project on, say, phytoplankton communities in small lakes should begin with a survey of relevant literature, which will reveal customary sampling procedures, which may be adopted or else adapted in view of the investigator's particular needs.