Applied Wetlands Science - Chapter 8

Kent, Donald M. “Monitoring Wetlands” Applied Wetlands Science and Technology Editor Donald M. Kent Boca Raton: CRC Press LLC,2001 CHAPTER 8 Monitoring Wetlands Donald M. Kent CONTENTS Reasons for Monitoring Measures Properties of Individual Plants Properties of Vegetation Communities Landform Properties Properties of Soil Hydrologic and Hydraulic Properties Aquatic Physical and Chemical Properties Organismal Properties Properties of Individual Wildlife and Fish Species Properties of Wildlife and Fish Communities Approaches to Monitoring Selecting a Monitoring Approach Investment and Return Investment, Return, and Area Investment, Return, and Time Measures and Monitoring Approaches Investment, Measures, and Area Investment, Measures, and Time Monitoring Design and Analysis Design Analysis References ©2001 CRC Press LLC Wetlands monitoring is the checking, watching, or tracking of wetlands for the purpose of collecting and interpreting data, which is then used to record or control the wetland or processes affecting the wetland. Not to be confused with wetlands assessment or evaluation which is the valuation of wetlands, monitoring of wetlands is a component of mitigation efforts (Kusler and Kentula, 1990; U.S. Army Corps of Engineers, 1989), the Environmental Protection Agency’s Environmental Moni-toring and Assessment Program (Paul et al., 1990; Leibowitz et al., 1991), and other programs designed to protect, conserve, and understand wetland resources (New Hampshire Water Pollution Control Commission, 1989; Haddad, 1990; Walker, 1991). Monitoring efforts are conducted for several reasons using a variety of techniques to measure and assess an array of structural and functional parameters. The process of developing and implementing a monitoring program can be reduced to four basic steps (Figure 1). First and foremost, the reason for monitoring must be identified and clearly stated. Second, a determination of the measures appropriate for achieving the stated objective(s) must be made. Third, an approach commensurate with the level of investment and the required return must be selected. The size of the area to be monitored, as well as the length of time the area will be monitored, will affect selection of an approach. Finally, the information gathered from the monitoring effort must be analyzed and interpreted. REASONS FOR MONITORING For the most part, wetland monitoring is conducted for a relatively few, discrete reasons. Habitat mapping and trend analysis monitoring are conducted to identify wetlands resources and to detect changes in these resources over time. Examples of mapping and trend analysis monitoring include efforts in coastal and seaway Canada (Rump, 1987), coastal India (Nayak et al., 1989), migratory bird habitat in central California (Peters, 1989), and the National Wetlands Inventory project (Dahl and Pywell, 1989). Perhaps the largest monitoring effort of this type is the Environmental Monitoring and Assessment Program (Paul et al., 1990; Liebowitz, 1991). The program, designed to monitor the condition of wetlands, has stimulated mapping and trend analysis monitoring throughout the United States (Haddad, 1990; Johnston and Handley, 1990; Orth et al., 1990). Initial aspects of the wetland ecosystems component of the Environmental Monitoring and Assessment Program focus on determining the sen-sitivity of various metrics for detecting known levels of stress and determining the spatial and temporal variability of proposed wetland indicators of condition (U.S. Environmental Protection Agency, 1990). Wildlife and fisheries management monitoring is also a type of habitat mapping and trend analysis monitoring. It is conducted to provide information about species richness and species abundance over time and to assess the effects of management strategies. The wildlife or fisheries population (Henny et al., 1972; Neilson and Green, 1981; Hink and Ohmart, 1984; Young, 1987; Molini, 1989), habitat indicators of wildlife richness and abundance (Weller and Fredrickson, 1974; Koeln et al., 1988), or both (Weller, 1979; Weller and Voigts, 1983) are monitored. ©2001 CRC Press LLC Figure 1 Steps for developing and implementing a wetland monitoring program. A second reason for monitoring is to determine the effectiveness of enhancement, restoration, and creation efforts. Examples include evaluation of habitat created using dredge spoil (Newling and Landin, 1985; Landin et al., 1989) and restoration of degraded habitats (Pacific Estuarine Research Laboratory, 1990). There are numer-ous monitoring efforts associated with Section 404, state, and local wetland fill permits (Kusler and Kentula, 1989; U.S. Army Corps of Engineers, 1989; Erwin, 1991) as well. Impact analysis constitutes a third reason for monitoring. Monitoring is con-ducted to determine the response of wetlands to identified direct and indirect impacts. Examples include monitoring of impacts to wetlands on and adjacent to hazardous waste sites (Watson et al., 1985; Hebert et al., 1990), as well as impacts from discrete and continuous chemical contamination events (McFarlane and Watson, 1977; Woodward et al., 1988). Other examples of impact analysis monitoring include studies of the effects of highway construction (Cramer and Hopkins, 1981), siting impacts from generating station construction and operation (Wynn and Kiefer, 1977), ©2001 CRC Press LLC effects on wetland flora from exposure to electromagnetic fields (Guntenspergen et al., 1989), and impacts from agricultural practices (Hawkins and Stewart, 1990; Walker, 1991). Finally, wetlands may be monitored to determine the potential for, or effective-ness of, wetlands for treating point source or nonpoint source discharges. Treatment monitoring has been applied to studies of the effectiveness of constructed wetlands for domestic wastewater treatment (Hardy, 1988; Choate et al., 1990; Tennessee Valley Authority, 1990), mine drainage (Eger and Kapakko, 1988; Stark et al., 1988; Stillings et al., 1988), stormwater runoff (Meiorin, 1991), and agricultural runoff (Costello, 1991). MEASURES A large number of measures have been applied, or potentially can be applied, to monitoring of wetland structure and function (Table 1). Commonly used measures include measures of the properties of individual plants and animals, measures of the properties of vegetation and wildlife communities, measures of aquatic physical and chemical properties, and measures of soil properties. Less commonly used are measures of hydrologic and hydraulic properties such as flood frequency and ground-water depth. Generally unused are potentially useful measures of landform properties such as heterogeneity and patch characteristics (Forman and Godron, 1986). The latter properties are particularly important in the preservation and creation of wet-lands for wildlife and are likely to be useful for other aspects of habitat mapping and trend analysis monitoring. Measures of organismal properties are typical of impact analysis monitoring programs. Properties of Individual Plants Measures of the properties of individual plants are used to assess the condition of natural plants and propagules. In theory, the properties of a plant are affected by any factor that alters the growth and maintenance of the plant. Factors that affect plant growth and maintenance include soil nutrients, soil moisture, disease, pest infestations, and anthropogenic and other disturbances. Information obtained from measurements of the properties of individual plants can be applied to trend analysis monitoring, enhanced, restored, and created wetlands monitoring, impact analysis monitoring, and treatment monitoring. The simplest measure of an individual plant is survival, that is, whether the plant is dead or alive. For living plants, measures include basal area, which is the area of exposed stem if the plant were cut horizontally, and stem diameter, which is the maximum width of the area of exposed stem if the plant were cut horizontally. Basal area and stem diameter are usually measured in centimeters (2.5 cm equals 1 in.) above the ground by ecologists and range managers, and 1.4 m (4.5 ft) above the ground by foresters. Plant height is the mean vertical distance from the ground at the base of a plant to the uppermost level of a plant. Cover, including ground cover (herbaceous plants and low growing shrubs) and canopy cover (other shrubs and ©2001 CRC Press LLC ... - tailieumienphi.vn