Study Design and Logistics - Wetland Techniques - page 11

Nevada, USA, based on use of a wetland. If humans associated with the wetland
were sedentary (i.e., lived year-round in same place), then the human archaeolog-
ical evidence should be concentrated in and around the wetland with little evidence,
except for hunting parties, in surrounding mountains. If humans were nomadic and
they used the wetland as a stop-over point, then one would expect to find transient
evidence at the wetland and extensive evidence in surrounding mountains as people
roamed throughout the region. They then proposed a study, using proper design to
test the hypotheses; the final conclusion was that both hypotheses lacked support
and thus, additional hypotheses were generated based on the information generated
during the study.
While development and testing of competing hypotheses should be the goal of
wetland investigations, it should be noted that descriptive research (i.e., natural
history), long-term monitoring of ecological systems and their components, estima-
tion of magnitudes of effects, and documentation of changes in status of ecological
systems are valid and informative provided that the methodology is not flawed.
Results from these types of studies can be used to generate hypotheses for additional
testing, document historical or baseline conditions for future comparison, provide
input for policy and economic decision makers, and document ecological conditions
and responses for future use. Indeed, these types of studies are quite common, but one
must realize that conclusions based on these efforts can be considered premature
pending a rigorous test of competing hypotheses intended to explain observed
patterns, trends, and relationships.
1.4 Study Population
After hypotheses or objectives are explicitly stated, the focus of study design shifts
to the process of devising a study to test the hypotheses. Inherent to proper study
design is the identification of a population to define the biological entity of interest
and placement of bounds on the scope of the experiment. A biological population
is defined as a “group of organisms of the same species occupying a particular space
at a particular time” (Krebs 1985 : 157). A metapopulation is formed when the
population of interest is subdivided into discrete patches across a landscape but
movement among patches remains (Levins 1969 ). Often, in wetland science, one is
also interested in communities , which is “any assemblage of populations of living
organisms in a prescribed area” (Krebs 1985 : 435).
However, from a statistical and study design perspective, population has a
broader meaning than just an organismal definition. It is the total set of elements
or membership of a defined class of organisms, objects, or events. For wetland
studies, the population of interest may consist of the wetland type, ecological
condition of wetlands, organisms depending on the wetland, or a variety of other
elements of the system. The statistical or target population is the foundation of
study design and subsequent application of results. The target population is
statistically (i.e., has measurable parameters with true, but usually unknown, values