Kent, Donald M. “Monitoring Wetlands” Applied Wetlands Science and Technology Editor Donald M. Kent Boca Raton: CRC Press LLC,2001 ©2001 CRC Press LLC 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 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), Figure 1 Steps for developing and implementing a wetland monitoring program. ©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 trees), is that part of the ground area covered by the vertical projection downward of the aerial part of the plant. Typically, the vertical projection downward is viewed as a polygon drawn around the plant’s perimeter and ignores small gaps between branches. Canopy diameter is the average maximum width of the polygon used for canopy cover. Basal area, stem diameter, plant height, cover, and canopy diameter, if repeatedly measured over time, can be used as indicators of plant growth rate. Plants allocate net production to leaves, twigs, stem, bark, roots, flowers, and seeds. The accumulated living organic matter is the biomass and is usually expressed Table 1 Measures of Wetland Structure and Function Properties of individual plants Basal area Growth rate Biomass Productivity Canopy diameter Stem diameter Cover Survival Properties of vegetation communities Basal cover Evenness Biomass Richness Cover Survival Cover type Stratification Density Landform properties Accessibility Interaction Dispersion Shape Heterogeneity Size Isolation Properties of soil Classification Organic content Moisture Texture Hydrologic and hydraulic properties Flood storage volume Surface water depth Frequency of flooding Surface water area Groundwater depth Surface water velocity Groundwater recharge volume Surface water width Aquatic physical/chemical properties Biological oxygen demand pH Chlorophyll Salinity Turbidity Temperature Dissolved solids Toxicants Nutrients Organismal properties Behavior Metabolism Bioaccumulation Reproduction Growth and development Tissue health Properties of individual wildlife and fish species Abundance Density Association Mortality Age structure Presence/absence Properties of wildlife communities Abundance Evenness Biomass Niche overlap Density Richness ©2001 CRC Press LLC as the dry weight per unit of area. Determining the allocation to each part is generally invasive in that the parts must be removed from the plant and either weighed or analyzed for energy or nutrient content. Nevertheless, individual plant productivity can be estimated by sampling leaves, flowers, or seeds (Figure 2). Properties of Vegetation Communities Just as factors that affect plant growth and maintenance are reflected in mea- surements of the properties of individual plants, factors which affect more than one individual plant will be reflected in measurements of the properties of vegetation communities. Therefore, measures of the properties of vegetation communities are of use in assessing the condition of natural and mitigated vegetation communities. Measures of the properties of vegetation communities include extensions of the measures applied to individual plants as well as measures which are unique to the characterization of communities. Measures of community survival, basal Figure 2 Monitoring of individual plants during the appropriate season will indicate if repro- duction is occurring. Productivity can be estimated by sampling leaves, flowers, or seeds. ©2001 CRC Press LLC cover, cover, and biomass require the accumulation of measures of individual plants. The cumulative expression of these measures, relative to the number of individuals assessed in the case of survival, or relative to the size of the area assessed in the case of basal cover and cover, provides for the description of the vegetation community. Properties unique to vegetation communities include cover type, which is the assignment of the community or parts of the community, to predetermined categories (Figure 3). “Classification of wetlands and deepwater habitats of the United States” (Cowardin et al., 1979) is the most commonly used system for describing cover type and its widespread use provides for comparison among disparate monitoring efforts. Nevertheless, the development of other descriptive systems is sometimes required in order to maximize information return. Other measures unique to the community level are density, which describes the number of individuals per unit of area, and richness, which is the list of plant species identified in the community of interest. If each individual plant within the sampling area is identified, then evenness can be determined. Evenness describes how the species abundances are distributed among the species. Another widely used measure of community structure, diversity, com- bines richness and evenness. Because diversity measures combine richness and evenness, they confound the number of species, the relative abundances of the species, and the homogeneity and size of the area sampled, and are, therefore, less useful than measures of richness and evenness. Finally, measures of stratification, a diversity index reflecting the amount of foliage at various levels above the ground, describe the vertical structure of the vegetation community. Figure 3 Wetlands can be monitored for cover type, which is the assignment of the plant community, in this case emergent macrophytes, to predetermined categories. ©2001 CRC Press LLC Landform Properties Measures of landform properties are used by landscape ecologists to identify and describe individual communities and the relationships among communities. The measures can be valuable to wetland scientists interested in local and regional planning issues, particularly because these issues relate to wildlife and trend analysis. However, the measures have been infrequently used and, therefore, require precise definition and identification of limitations, when applied. Some measures of landform properties, such as shape and size, can be applied to studies of single wetlands. Shape is typically described as a ratio of wetland perimeter to wetland area (Bowen and Burgess, 1981). Size is described as the area of the wetland or by some linear dimension such as length, width, or the ratio of length to width. Other measures of landform properties require consideration of more than a single wetland. Accessibility describes the distance along a corridor of suitable habitat from one wetland to another and reflects the perceived ease of species movement (Bowen and Burgess, 1981). Dispersion describes the pattern (e.g., clumped, uniform, random) of spatial arrangement among wetlands (Pielou, 1977). Isolation describes the distance of a wetland from other wetlands (Bowen and Burgess, 1981) and interaction describes the perceived influence of a wetland on another wetland through consideration of the distance between wetlands (MacClintock et al., 1977). Properties of Soil Measures of the properties of soils are useful in describing wetland structure and provide clues to wetland function. As part of mapping and trend analysis monitoring efforts, measures of soil properties help to distinguish between wetland and nonwetland areas and provide information as to changes to these areas. If monitored as part of a wetland enhancement, restoration, or creation effort, including efforts associated with the establishment of treatment wetlands, measures of the properties of soil indicate the development of hydric conditions. Soil is typically classified according to such characters as color, texture, and size and shape of aggregates. The Department of Agriculture Soil Conservation Service system is the commonly used taxonomic classification system in the United States. Based upon the kind and character of soil properties and the arrangement of horizons within the profile, the system also provides information about the use and manage- ment of the soil. Soil texture is based on the relative proportions of the various soil separates in a sample and is estimated from its plasticity when extruded and by feeling its grittiness (Hays et al., 1981). Soil moisture is the percent of a given amount of soil consisting of water and is estimated by the loss of weight on drying. Soil organic content is the percent of a given amount of soil consisting of organic matter and is estimated by loss of weight upon ignition. ©2001 CRC Press LLC Hydrologic and Hydraulic Properties Simply stated, a wetland is a wetland because it is wet. Hydrologic and hydraulic measures provide useful descriptors of wetland structure and also provide valuable information as to wetland function. Measures of hydrologic and hydraulic properties provide information about the extent of wetlands as well as the effect of intrinsic and extrinsic changes to wetlands. Treatment monitoring benefits from measures of hydrologic and hydraulic properties in determining maximum treatment capacity. Measures of hydrologic and hydraulic properties as part of enhanced, restored, and created wetland efforts are integral to an assessment of project success. Velocity describes the speed at which water travels and reflects not only the depth and width of the water body, but also the topographical gradient and the extent and type of vegetation. Water depth, width, and area are descriptors of wetland structure. Monitored over time, and in relation to extreme events, these measures provide an empirical estimate of the frequency of flooding and of flood storage volume. Flood storage volume can also be estimated using one of a number of computerized hydrological models (U.S. Army Corps of Engineers, 1981; Soil Conservation Service Hydrology Units 1982 and 1986; Huber and Dickinson, 1988). Model inputs include wetland and watershed slope, vegetative cover, soil type, and surface type (i.e., pervious or impervious). Groundwater depth, the distance below the ground surface at which water occurs, can be determined empirically through the installation and monitoring of wells (Figure 4). Ground- water recharge volume, the volume of surface water moving down through the soil to an underlying groundwater system or aquifer, can be estimated using the afore- mentioned hydrological models. Aquatic Physical and Chemical Properties The quality of water affects the growth, maintenance, and reproduction of wet- land flora and fauna. Wetland water quality is revealed by measures of aquatic physical and chemical properties. Water quality reflects the condition of the sur- rounding environment and is affected by human activities such as watershed erosion and point and nonpoint source discharges. Wetland water quality also reflects the condition of the wetland itself. Measures of aquatic physical and chemical properties are particularly applicable to monitoring of the effects of impacts to wetlands and monitoring the effectiveness of treatment wetlands. Water temperature influences the rate of metabolic reactions, the reactivity of enzymes, and the amount of oxygen that can be dissolved in water. The pH of water affects organismal physiological reactions and membrane characteristics. Dissolved oxygen concentrations must be sufficient to enable diffusion from the water into an animal’s blood. Salinity affects water quality through its effect on the ability of species to maintain osmotic balance. Turbidity restricts the depth to which solar radiation can penetrate the water column. Dissolved solids, such as carbonates, bicarbonates, chlorides, phosphates, nitrates, and salts of calcium, magnesium, sodium, and potassium, affect organismal ionic balance and other physiological processes. Biological oxygen demand, the amount of oxygen required by bacteria [...]... 1 985 ; Watson et al., 1 985 ; Eger and Kapakko, 1 988 ; Hardy, 1 988 ; Pritchett, 1 988 ; Shortelle et al., 1 989 ; Clausen and Johnson, 1990; Conner and Toliver, 1990; Hebert et al., 1990; Oberts and Osgood, 1991; Walker, 1991) Specific measurement parameters used in contact monitoring are discussed in Hays et al (1 981 ), Cooperrider et al (1 986 ), Graves and Dittberner (1 986 ), and Adamus and Brandt (1990) Historically,... 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Environmental Restoration: Science and Strategies for Restoring the Earth, University of California Press, Berkeley, CA, 1 988 , 282 Roughgarden, J., Running, S W., and Matson, P l A., What does remote sensing do for ecology? Ecology, 72(6), 19 18, 1991 Rump, P C., The state of Canada’s wetlands, in Proceedings of the Peatlands Symposium, Association of State Wetland Managers, Edmonton, Canada, 1 987 , 259 Shortelle,... Vernal pool wetlands: wildlife values, acidification and a need for management, in AWRA Wetlands: Concerns and Successes Symposium, American Water Resources Association, Tampa, FL, 1 989 , 463 Soil Conservation Service, Technical release no 20 (TR-20), National Technical Information Service, 1 982 Soil Conservation Service, Technical release no 55 (TR-55), National Technical Information Service, 1 986 Stark,... successional changes (Mackey and Jensen, 1 989 ; Nayak et al., 1 989 ; Byrne and Dabrowska-Zielinska, 1 981 ) Information is provided at mesoscale, macroscale, ©2001 CRC Press LLC Figure 6 Fish community species richness and abundance can be monitored using fish traps such as this fyke net and megascale levels (see Table 2 adapted from Delcourt and Delcourt, 1 988 ) Aerial photography provides similar information . wildlife and fish (Cramer and Hopkins, 1 981 ; Bosserman and Hill, 1 985 ; Watson et al., 1 985 ; Eger and Kapakko, 1 988 ; Hardy, 1 988 ; Pritchett, 1 988 ; Shortelle et al., 1 989 ; Clausen and Johnson, 1990; Conner. Kapakko, 1 988 ; Stark et al., 1 988 ; Stillings et al., 1 988 ), stormwater runoff (Meiorin, 1991), and agricultural runoff (Costello, 1991). MEASURES A large number of measures have been applied, . Donald M. “Monitoring Wetlands Applied Wetlands Science and Technology Editor Donald M. Kent Boca Raton: CRC Press LLC,2001 ©2001 CRC Press LLC CHAPTER 8 Monitoring Wetlands Donald M.