Environmental Engineering Reference
In-Depth Information
a
b
c
Stratum 2
Upland
Stratum 1
Wetland
d
e
f
.
Fig. 1.3
Examples of sampling design for wetlands including (
a
) simple random design, (
b
)
systematic sampling, (
c
) stratified random sampling, and (
d
) systematic use of a grid to select
sample area. Examples of sampling method are (
e
) plots along transects and (
f
) line transect
that lead to hypotheses, and generate data to be used in a modeling study (Morrison
et al.
2001
). The most common type of judgment sampling is restricting data
collection only to those wetlands that are known to contain the variable of interest
(e.g., certain amphibian species, distinctive watershed conditions). Once again,
inference is strictly limited to the experimental units sampled, with extension to
other subjects of the target population to be considered tentative at best.
Dobbie et al. (
2008
) stated that professional judgment and opinion were critical
in designing monitoring programs of aquatic systems. Cohen et al. (
2005
) used
scientific judgment to rank relative impairment of wetlands and then sampled
wetlands based on categories of ecological condition. Hopfensperger et al. (
2006
)
made a case for the use of profession judgment for situations where no prior
information is available when evaluating the feasibility of restoring a wetland.
Search sampling
is based on historical information. Frequently, this informa-
tion is available from results of long-term inventory and monitoring programs.
Typically, this sampling involves using
a priori
knowledge to select areas to
sample. This type of sampling differs from judgment sampling in that sampling
