Environmental Engineering Reference
In-Depth Information
Williams BK (1997) Logic and science in wildlife biology. J Wildl Manag 61:1007-1015
Williams BK (2012) Reducing uncertainty about objective functions in adaptive management.
Ecol Model 225:61-65
Williams BK, Brown ED (2012) Adaptive management: the U.S. Department of the Interior
Applications Guide. Adaptive Management Working Group, U.S. Department of the Interior,
Washington, DC
Zimmer KD, Hanson MA, Butler MG (2001) Effects of fathead minnow colonization and removal
on a prairie wetland ecosystem. Ecosystems 4:346-357
Student Exercises
Classroom Exercise
In wetland studies, there are usually a number of acceptable study designs to
generate knowledge regarding an observed ecological pattern or process, effects
of management or anthropogenic impacts, or approximation to a desirable condi-
tion or state. The key is use of a defensible study design that allows an investigator
to make reliable conclusions and inference from the results of data collection and
statistical analysis. Use of critical thought through the study design process prior to
data collection will ensure dependable results that can be used to advance under-
standing of the wetland system being studied and hypotheses being tested.
Many wetland systems are actively managed for certain ecological responses
through application of specific environmental conditions; for example, water-level
manipulation. These ecological responses are typically production of food resources
(e.g., seeds, tubers, invertebrates) for wetland-dependent wildlife. Development of
management prescriptions to maximize food production typically requires a set of
manipulative experiments to test wetland response to a variety of different environ-
mental conditions. However, measurements of food resources in wetlands can occur
without manipulated experiments by relating (e.g., correlated) resource production
to observed environmental conditions. Such an approach does provide some evi-
dence of influential variables relative to production of food resources, but lacks rigor
to produce a complete understanding of causal relationships. Therefore, it is crucial
for investigators to properly design studies of appropriate rigor to generate knowl-
edge of sufficient scientific quality to meet the study objectives.
When managing wetlands for wildlife-forage resources, characteristic environ-
mental conditions that are frequently tested include frequency and timing of
wetland drawdowns (dewater to expose soils and sediments) and flooding that
affects soil moisture and temperature; oxygen content in soil and water (i.e., aerobic
vs. anaerobic conditions); and nutrient availability (e.g., nitrogen, phosphorus).
Typically, investigators collect and measure invertebrate and plant response to
(1) determine species composition in response to treatments and (2) estimate
available biomass of forage resources. In addition, relative composition, distribu-
tion, and variation among studied wetlands of source populations (i.e., seed and egg
banks) for food resources are characteristically considered influential on results but
