Geoscience Reference
In-Depth Information
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Introduction
Bryan Manly and Jorge Navarro
1.1 Why a Topic on Ecological Sampling and Analysis?
Some biological sciences, like agronomy, physiology, and the like, share con-
cepts and research methods with the science of ecology, but there are obvi-
ous differences regarding the way data are gathered. In the former subjects,
designed experiments with the sampling processes carried out under con-
trolled conditions are more often performed. Although the use of experi-
ments in ecology has always been suggested in order to gain a better idea
of cause-and-effect relationships (Underwood, 1997), this is often difficult
or impossible, and ecologists are compelled to use observational methods
of sampling. Moreover, there are multidisciplinary areas combining the eco-
logical component and socioeconomic approaches (e.g., ethnobiology, natu-
ral resource management) in which the only sampling strategy available is a
nonexperimental, observational approach.
Many ideas behind sampling in ecology have their roots in methods pro-
vided by a classic discipline in statistics, namely, survey sampling of finite
populations. Simple random sampling, stratified sampling, and systematic
sampling are all firsthand tools applicable to ecological studies. However,
there are often particular problems faced by ecologists for sampling real ani-
mal or plant populations that have made both ecologists and statisticians
develop special sampling methods that take into account the peculiarities
of the situation of interest. There are numerous examples of such methods,
including mark-recapture sampling, adaptive sampling, removal sampling,
and so on. Our purpose in presenting this topic is to cover both the classic
approaches and the methods needed by working ecologists.
Although the sampling procedures covered in this topic are diverse, they
are unified by the widespread interest in ecological studies of estimating
biological (e.g., population size and density) and environmental (e.g., the
concentration of chemical elements) parameters. Thus, this topic emphasizes
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