263 Selection of Ecological Indicators for Monitoring Terrestrial Systems G.J. White CONTENTS 10.1 Introduction 263 10.2 Objective and Approach 265 10.3 Monitoring Terrestrial Ecosystems—Design and Considerations 266 10.4 Selection of Indicators of Ecosystem Status 270 10.5 Conclusions 279 References 281 10.1 INTRODUCTION In recent years, the importance of assessing the condition of ecological systems including wilderness and other protected lands from atmospheric pollutants and other anthropogenic and natural factors has become widely recognized. Monitoring and assessment of natural systems are increasingly focusing on the application of indi- cators of ecosystem status, and substantial efforts are currently being devoted to the identification and development of suitable indicators (National Research Council, 1986; Noss, 1990; Messer et al., 1991; Bruns et al., 1991, 1997; Kurtz et al., 2001). However, accurate assessment of impacts to ecological systems has been hampered by a general lack of information in many key areas or by the failure to collect and/or consider the information that is available. Assessment of the condition of ecological systems is further complicated by the vast diversity in structure, extent, and composition of these ecosystems, and in many cases by the harsh environments and difficult access associated with many sites. Given the diversity of ecological systems, data collected in one geographic area may not be fully applicable to others even if the two areas are located near one another. Furthermore, extensive physical, chemical, and biological monitoring programs are often impractical due to cost constraints and other factors. The challenge is to develop a program that will answer the pertinent monitoring questions in the most cost- effective manner. 10 L1641_C10.fm Page 263 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC 264 Environmental Monitoring During the 1990s, federal land management agencies in the U.S., including the Forest Service, Park Service, Fish and Wildlife Service, and Bureau of Land Manage- ment, began to develop and document processes for establishing pollutant effects mon- itoring programs in Class I wilderness areas. The focus of these monitoring programs was to provide early detection of the effects of atmospheric pollutants on ecological systems. Toward that end, several guideline documents were published describing how pollutant effects monitoring programs should be designed (Adams et al., 1991; Schmoldt and Peterson, 1991; J. Peterson et al., 1992; D.L. Peterson et al., 1992; Peine et al., 1995). These documents relied heavily on the use of indicators of ecosystem status and served to illustrate some of the difficulties encountered in making such assessments. In most cases, these documents concluded that adequate baseline infor- mation was rarely available, greatly increasing the difficulty associated with selection of indicators of ecosystem status. Complicating this selection process is the fact that monitoring programs that utilize ecological indicators must be established on a site-by- site basis. This is important not only because each potential area of interest is unique geologically, hydrologically, and ecologically, but also because each factor conferring change on the system is at least somewhat unique. Ecological monitoring programs must be designed to address the specific stressor and protected area independently, as a program designed for one scenario will not necessarily be applicable to another. To establish an effective assessment program based on the implementation of indicators, the following questions should be answered: 1. Which resources (or critical receptors) are potentially of concern, and where are they located? 2. Which perturbation factors are potentially responsible for impacting these receptors? 3. Which indicators will best detect the impacts of the perturbation factors on the sensitive receptors? 4. At what specific locations should the indicators be examined? 5. At what frequency should these indicators be examined? 6. What degree of change indicates cause-and-effect? All of these questions should be addressed within the context of sound science. Monitoring involves the continual systematic time series observation of an appro- priate suite of predetermined chemical, physical, and/or biological parameters within the appropriate components of the appropriate ecosystem, for an appropriate period of time that is sufficient to determine (1) existing conditions, (2) trends, and (3) natural variations of each component measured (Segar, 1986). To accomplish this, monitoring programs must be designed properly. The most important step in the design of any monitoring program is the definition of the objectives of the program. Only when specific objectives such as these have been established can the scientific method of establishing and testing hypotheses be applied (Segar, 1986). These objectives must adequately define: • The specific receptor to be evaluated • The specific effect to be monitored • The level of effect that bounds acceptable vs. unacceptable conditions L1641_C10.fm Page 264 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC Selection of Ecological Indicators for Monitoring Terrestrial Systems 265 To effectively meet the objectives of an ecological monitoring program, moni- toring must be designed to detect changes in indicators that are both measurable and significant. It is not realistic to design a monitoring program to assess the concentration of every potential perturbation factor in all media at all locations that might be impacted, in order to detect any change in the degree of perturbation. Similarly, ecological monitoring cannot be conducted to identify any change in the abundance, health, growth rate, reproductive rate, etc., of any species or community which is caused by any potential perturbation factor (Segar, 1986). Such goals are neither realistic nor attainable. By definition, indicators must be indicative of some unmeasured or unknown condition (Suter, 2001). As will be discussed later in greater detail, the selection of ecological indicators must consider the roles of these indicators within the dynamics of the system to be monitored, the degree to which these roles are understood, and the certainty associated with observed levels of the indicators. Candidate indicators should therefore represent measures that, based on expert knowledge and available literature, will provide useful information concerning the condition of the ecosystem being monitored. Criteria must be established that can be used to assess the effec- tiveness of indicators to ensure that: 1. The resulting data will be sufficient to answer the pertinent questions regarding the status of the ecological system of interest. 2. The resulting data are of known and acceptable quality. 3. The monitoring program can be implemented in a cost-effective manner. These criteria should then be applied to the selection of indicators of the con- dition of the ecological systems in question, and monitoring programs based on the measurements of these indicators may then be designed in a manner that will provide cost-effective, scientifically based assessment of ecosystem status. Without applying a consistent, scientific approach, it is difficult to predict which indicators will best reflect the potential effects due to specific perturbation factors, or to select the most effective methods for monitoring these effects. 10.2 OBJECTIVE AND APPROACH The purpose of this chapter is to describe criteria for selecting ecological indicators for use in monitoring the status of ecological systems. Although the approach described in this document is intended to be generic in that it is applicable to virtually any situation, the output must be considered site-specific at both ends of the stres- sor/receptor continuum. Furthermore, although the emphasis is on terrestrial systems, the process can be applied equally to developing monitoring for aquatic systems. A series of criteria is proposed by which potential indicators of cause and effects relationships may be evaluated. By applying these criteria during the planning stage, it is anticipated that monitoring programs can be more readily developed to provide defensible, quality-assured data in the most cost-effective manner. The general approach proposed here for developing a monitoring program based on the application of ecological indicators is as follows: L1641_C10.fm Page 265 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC 266 Environmental Monitoring 1. Gather pertinent site-specific information on (i) the ecosystems of con- cern; (ii) the potential critical receptors or components within the ecosys- tems; (iii) the factors that potentially impact the health of these ecosystems and/or components (e.g., disease, air pollution deposition, urban encroach- ment, invasion of exotic species, logging, etc.); and (iv) the relationship between the stressors and the receptors. 2. Develop a conceptual framework using this information to illustrate and understand the dynamics of the systems of interest. 3. Establish and rank criteria for evaluating potential indicators of ecosystem change and use these criteria to select the appropriate indicators for assessing changes in the status of the ecological systems. 4. Develop hypotheses to be tested using the indicators selected. The general intent of this document is therefore to help with the development of scientifically defensible, cost-effective monitoring programs to assess the status of ecological systems. Much of the discussion is focused on relatively pristine ecological systems, as these are likely to prove more difficult in determining cause and effect relationships. 10.3 MONITORING TERRESTRIAL ECOSYSTEMS— DESIGN AND CONSIDERATIONS The first step in designing a monitoring and assessment program for terrestrial ecosystems is to gather the information necessary to develop a conceptual design or model for the program. This involves compilation of information relating to the ecosystem of concern (including critical components of the ecosystem) and the factors that may potentially alter the status of the ecosystem or critical ecosystem components. It also involves determining the relationships between the potential perturbation factors and the critical receptors of components of concern. Collectively, this information is incorporated into a conceptual model for the system of interest. This model is then used to design the monitoring approach. The first step in this approach is to identify what resources are of concern and where these resources of concern are located. This is obviously tied to the goal of the proposed monitoring program. Often this determination is one of scale. If the concern is die-off of sugar maple, then the receptor of interest is a single species, but the area of concern may be the entire range of the species, covering a couple of dozen states and much of southeastern Canada. Alternatively, the goal of the mon- itoring program could be to determine the status of ecological systems within Yellowstone National Park. Here, the area of concern is defined by the boundaries of the Park, but the ecosystem components of interest could include any or all species found in the Park. Spatial scales could be considerably smaller, however, such as a watershed or a single stand of trees. Once the resources of concern have been identified, the next step is to determine what factors or agents may impact the status of those resources. These may include either natural factors such as fire, disease, weather and climate, or anthropogenic factors L1641_C10.fm Page 266 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC Selection of Ecological Indicators for Monitoring Terrestrial Systems 267 such as atmospheric pollutants, logging, or other land use activities. In some cases (e.g., fire) it may be difficult to separate the natural from the anthropogenic. In many instances, the perturbation factors are well known and provide a known impetus for establishment of an ecological monitoring program. The government programs to determine air pollution impacts to Class 1 airsheds, for example, were charged with determining the effects to terrestrial and aquatic ecosystems resulting from a specific cause (air pollution). Similarly, monitoring Douglas-fir forests for spruce budworm damage links a specific cause with a specific effect. It should be pointed out that not all monitoring programs are charged with determining a specific cause of a specific effect in an individual species at a specific location. At the other extreme, a monitoring program may be designed to determine the status and trends of “ecosystem health” throughout a given biome such as tropical rainforests or alpine tundra. In these instances, it is still recommended that specific perturbations and receptors be identified. Once the system is defined in terms of location, perturbation factors, and critical receptors or components, it is often useful to develop a conceptual model of the system of concern. These conceptual models may take the form of a simple “box- and-arrow” diagram that describes the structure and function of the ecosystem or ecosystem components of concern (e.g., Figure 10.1). In these diagrams, each “box” represents some component of the ecosystem, while the arrows illustrate the transfer of nutrients, contaminants, or energy between components. Such diagrams can help to visualize the dynamics of pollutants in the environment. Thus conceptualized, mathematical models may be applied using the conceptual model to quantify the rates at which materials are expected to move through the system. Such an approach allows for periodic reevaluation of data sets based on model calculations, which FIGURE 10.1 “Box-and-arrow” diagram used to conceptualize an ecological system during the development of a monitoring program. Atmosphere Soil Micro-Macro Flora/Fauna Vegetation Litter / Humus Mineral Soil Deeper Soil Terrestrial Fauna Groundwater Sediment Aquatic Micro-Macro- Flora/Fauna Surface Water Wet Dry Wet Dry Dry Wet Short- and Long-Range Sources L1641_C10.fm Page 267 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC 268 Environmental Monitoring ultimately may allow for the modification of the monitoring system design in such a way as to improve cost-effectiveness. Conceptual diagrams may be considerably more complex than that shown in aspects of the monitoring program design. The diagram in Figure 10.1 has been used to monitor the impacts from air pollutants on terrestrial and aquatic ecosystems in the western U.S. and elsewhere (Bruns et al., 1991). In contaminant monitoring programs, these diagrams can help determine source–receptor relationships, con- taminant pathways, critical receptors, and the ultimate fate of contaminants. This is conducive to an ecosystem approach to environmental monitoring whereby interrelationships between different components of the system are considered, recognizing that alterations to one component of the system may affect other components. Conceptual models help to provide information that may be used to help determine which receptors are at risk from which stressors, and what indi- cators should be used to quantitatively link the stressors to critical receptors. This approach provides for the effective integration of various indicators of change that will enable the evaluation of the system as a whole. Models can also help to identify gaps in the existing data. Once the appropriate stressors and receptors have been identified, it is important to narrow the focus of the potential relationship between source and receptor. It is not enough to determine that a stressor may cause impacts to a particular receptor. Rather, information is needed on the species or communities of plants that may be at risk, the anticipated responses of these species or communities, and the exposures necessary to elicit these responses. • What are the effects of the identified stressors on the identified ecosystems or ecosystem components? • At what level of biological organization do the stressors operate? • Which stressors are responsible for these changes? • What is the mode of action by which the effect occurs? • What characteristics (e.g., temporal component, etc.) control the effect? • What characteristics of the site are involved? • To what degree can laboratory data be extrapolated to the field? Effects of stressors on ecological systems are extremely complex and diverse. Effects from atmospheric pollutants, for example, may be classified variously as direct vs. indirect, acute vs. chronic, lethal vs. sublethal, biotic vs. abiotic, visible vs. micro- scopic, positive vs. negative, etc. Furthermore, it is important that effects be considered for all levels of biological organization. Not only may effects be observed at the ecosystem, community, population, or individual levels of biological organization, but at the other extreme, effects may also be observed at the cellular, biochemical, or genetic levels. Potential effects on ecological systems due to stressors must be iden- tified even if there is no obvious evidence that this damage is occurring. The specific stressors potentially responsible for each effect must also be determined, integrating dose/response information wherever possible. To complicate matters further, the possibility of synergistic effects brought about by a combination of stress L1641_C10.fm Page 268 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC Figure 10.1 and may be used as heuristic tools for establishing many of the key Selection of Ecological Indicators for Monitoring Terrestrial Systems 269 agents must also be considered. Other potential causal or contributing factors should also be identified. These could represent additional independent stress factors (e.g., drought, pathogens, insect pests), or factors associated with the environment (e.g., soil pH, temperature, etc.) or with the organism itself (e.g., physiological, morphological, and other features of the organism that renders it susceptible). The response of organ- isms to stressors may vary substantially among sites, even if exposures are the same. This may be due to differences in receptor species (species composition and density, age class distribution, genetic pools) or by differences in the site (e.g., elevation, slope, aspect, solar incidence, precipitation, etc.). Soil characteristics (e.g., pH, percent organic matter, cation exchange capacity, percent base saturation, depth, sulfate adsorp- tion capacity, fertility, buffering capacity, etc.) may be especially important. Once the stressor/receptor relationships have been determined, the mode of action by which the effect occurs must be assessed. This requires an understanding of the mechanism of action involved with the interaction between pollutant and receptor. How is exposure duration (both instantaneous and chronic) and/or fre- quency involved in the manifestation of effects? Considerable information exists on the effects from short-term pollutant exposures for many plant species. However, little data are available on the effects from long-term or chronic exposures. Organisms, not ecosystems, respond directly to stress, and higher levels of biological organization in turn integrate the responses of the various individuals through various trophic and competitive interactions before an ecosystem-level response can be observed (Sigal and Suter, 1987) without a prior organism response. Responses of organism therefore precede those of ecosystems, and in the process of monitoring the parameters of entire ecosystems, the responses of sensitive indi- viduals and populations tend to be masked or averaged out. Observations of impacts at the organism-level biological organization are relatively easy and inexpensive to measure (Sigal and Suter, 1987). Information linking these organism-based param- eters to adverse impacts on higher levels of biological organization (i.e., populations, communities, or ecosystems) are generally lacking and are confounded by natural variability, extended response times, variability of climatic conditions, influences of pathogens and insect pests, and other factors (Sigal and Suter, 1987). Information must also be compiled on a site-specific basis. Information on the individual ecological system of interest is necessary because all ecological systems are at least to some extent unique. If vegetation is the focus, then the distribution of various species and communities are needed. Data on soil development, soil chemistry, insect and disease history, meteorological parameters, and physical parameters (e.g., slope, aspect, elevation) may also be helpful. Collection of these types of information will help in the subsequent steps in the development of an approach for monitoring the status of the system. Questions to ask include: 1. What information is available for the ecosystem or ecosystem components (i.e., receptors) of concern? 2. What information is available on factors potentially responsible for caus- ing stress or change to these receptors? 3. What information is available from other areas sharing similar ecological, geological, and geographical properties? L1641_C10.fm Page 269 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC 270 Environmental Monitoring The specific locations where monitoring will be most effective must also be determined. Using the information generated in the above steps, candidate locations should be identified to conduct monitoring. Criteria should be established with which to evaluate candidate sites, and then these sites should be ranked using these criteria. Monitoring locations selected may not be the same for each receptor, or for each parameter or indicator measured for a given receptor, but should be based on where the best information can be obtained in the most cost-effective manner. Once a list of candidate monitoring sites is selected, the sites must be ranked such that the “best” subset of sites is selected for monitoring the status of the resource. Although many different sites may meet the basic requirements for a monitoring location, it is desirable to select the optimum site (or sites) for each receptor to be assessed. 10.4 SELECTION OF INDICATORS OF ECOSYSTEM STATUS Only now are we ready to change the emphasis from “what” and “where” to “how.” Specifically, how can impacts to sensitive receptors best be assessed? Methods must be identified or developed with which to assess the condition of receptors of concern. For example, if aspen are identified as potentially sensitive receptors for SO 2 deposition in a particular location, methods must be applied that will allow for the assessment of the status of the aspen at that specific selected location. Indicators must be identified that will allow impacts to aspen from SO 2 to be quantified. These indicators may be chemical, physical, or biological (ecological) measurements that individually or col- lectively will allow for the evaluation of the aspen growing at that site. A method is proposed here for selecting the most effective suite of indicators for assessing the status of a particular sensitive receptor or group of ecological receptors within a given geographic area. The process involves the application of a list of criteria for selecting the appropriate suite of indicators. Once the criteria list is established, the criteria may be ranked in terms of their relative importance to the success of the monitoring program. This identification and ranking of criteria is performed before actual indicators are considered; only after criteria are established are potential indicators evaluated against one another. By applying these criteria to indicator selection during the planning stage, monitoring programs can be developed to better provide defensible, quality-assured data in a cost-effective manner. Estab- lishing selection criteria early in the overall process helps to assure that the moni- toring program will adequately provide the necessary answers to questions regarding the status of the ecological systems. The purpose of establishing criteria with which to evaluate potential indicators is to define a priori the characteristic properties that an indicator or indicators should possess in order to be effective. This approach is recommended to avoid some of the problems common to many existing monitoring programs whereby ecological indicators fail to provide the information necessary to evaluate the condition of the resource being monitored (D.L. Peterson et al., 1992; J. Peterson et al., 1992). The criteria developed should be used to bind potential ecological indicators in a manner that will better ensure that the data produced are of known quality and are collected in the most cost-effective manner. L1641_C10.fm Page 270 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC Selection of Ecological Indicators for Monitoring Terrestrial Systems 271 As indicated earlier, ecological monitoring programs must be designed for each combination of stressor and receptor independently, as each combination is at least somewhat unique. A monitoring program designed for one scenario will not neces- sarily be applicable to another, and the monitoring design must therefore be estab- lished on a site-by-site basis. The criteria presented below are of varying importance, and reaching consensus opinions regarding the relative importance of each criterion may be difficult. Furthermore, the relative importance of each may vary among sites. The goal is to apply these and/or other alternative criteria to provide a consistent, generic approach to the selection of indicators. This approach can be applied in virtually any situation (i.e., any combination of source and receptor of interest), but the output must be considered site-specific. CRITERION 1: Ecosystem Conceptual Approach — The ecosystem approach to environmental monitoring considers many features of ecosystem simul- taneously rather than focusing on single, isolated features of the environment. To satisfy the ecosystem conceptual approach criterion, indicator parameters must relate in a known way to the structure or function of the ecological system to be monitored so that the information obtained provides a “piece of the overall puzzle.” Individual parameters should directly or indirectly involve some physical, chemical, or biolog- ical process (or processes) associated with the atmospheric, terrestrial, and/or aquatic portions of the system. Many different approaches can be applied to ecological monitoring, and each may be classified as either reductionist or synthesist in terms of the general strategy employed. A reductionist approach to monitoring assesses each parameter indepen- dently, whereas a synthesist strategy incorporates a more holistic approach that addresses the interrelationships between different components of the system. The reductionist approach therefore recognizes that if one component of the system is altered or stressed in some way, there will be direct and/or indirect consequences to other components as well, and that each of these, in turn, will cause further changes to occur. For most aspects of ecological monitoring programs, particularly in relatively pristine areas, it is recommended that a synthesist or “ecosystem approach” be taken to better enable overall impacts to be assessed in an integrated manner rather than as isolated, independent events. The ecosystem conceptual approach criterion must be addressed at two levels. First, the approach should be applied to the overall monitoring program through the applica- help the user visualize relationships between the receptors and stressors within the ecosystem and may therefore be used to help identify indicators of ecosystem status. At the second level, each individual component of the monitoring program should be evaluated to see how well it fits into the ecosystem approach to monitoring. With regard to a particular indicator, the basic questions asked relating to the ecosystem conceptual approach include the following: 1. Is application of the particular indicator (or set of indicators) consistent with current concepts of ecosystem theory? 2. Does the indicator relate to some process or processes associated with the structure and/or function of the ecological system? In developing a suite L1641_C10.fm Page 271 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC tion of the systems conceptual models designed earlier (Figure 10.1). These models 272 Environmental Monitoring of indicators for assessing vegetation condition in Australia, a process involving 47 Australian experts recently identified 62 potential indicators of vegetation condition. These were equally representative of composi- tional (21), structural (20), and functional (21) attributes of biodiversity (Oliver, 2002) 3. Do the procedures to be used for measuring the indicator adequately document how that particular indicator (or set of indicators) fits within an ecosystem context? 4. Will the resulting data be useful in providing an adequate understanding of the system to be monitored? 5. If a particular indicator does not adequately satisfy the above, what alter- native indicators may be recommended to meet such a requirement? There are many good examples of indicators of ecosystem stress that meet the ecosystem conceptual approach to environmental monitoring. For example, litter decomposition and multimedia elemental analysis both provide information on the nutrient dynamics of the system. Vegetation surveys in the terrestrial system and analysis of functional feeding groups in aquatic systems can provide information on the structure of the ecosystem. Conversely, although parameters associated with visibility may represent impor- tant measurements, these do not fit well into the ecosystem conceptual approach because visibility is primarily an aesthetic issue rather than an ecological one. Visibility is therefore more effectively treated individually. CRITERION 2: Usability— The usability criterion relates to the level of doc- umentation available for each indicator measurement; the relative completeness and thoroughness of the procedures for measuring indicator parameter provide the best indication of the usability of that indicator. The usability criterion is therefore satisfied for indicators for which the level of supporting documentation is complete. Ideally, detailed standard operating procedures (SOPs) should be available (or be easily generated) for each parameter measured as part of the monitoring program, and these SOPs should represent generally accepted, standardized methods. If the methods used are not well established, then supporting documents describing earlier applications of the method should be available. Any supporting documents used to justify the choice of indicator measurements or necessary to implement the mea- surements should be identified and referenced within the SOPs for each parameter measured. Information on previous field testing of the SOPs and supporting docu- ments should be available as well. Good examples of indicator parameters that satisfy the usability criterion include the widely used methods for measuring wet deposition, water chemistry, and soil chemistry. Established procedures for monitoring wet deposition are available and have been used for over a decade as part of the National Acid Deposition Program (NADP). Procedures for analyzing the chemical properties of water and soil are also well established. These procedures have long histories of field use and generally satisfy the usability criterion. In contrast, measurements of many ecological indica- tors are made using variable techniques, with little or no consensus regarding the best methodology available. L1641_C10.fm Page 272 Tuesday, March 23, 2004 7:31 PM © 2004 by CRC Press LLC [...]... American mountain ash Eastern hemlock West Beara Seedlings/ha East Bear Seedlings/ha A and Y Seedlings/ha 487.5 15 93. 8 45 93. 8 131 2.5 75 0 35 81 .3 0 0 0 0 0 35 6 .3 2 137 .5 412.5 33 37.5 581 .3 187.5 1481 .3 2 43. 8 0 31 8.8 0 112.5 731 .3 1800 937 .5 1125 825 93. 8 2062.5 18.8 150 56 .3 56 .3 206 .3 0 116 43. 8 56 .3 9225 0 8062.5 Manipulated watershed Significantly different TABLE 11.5 Statistics for the Overall dbh of All... Sugar maple American beech Red maple Striped maple West Beara # Seeds/ha East Bear # Seeds/ha A and Y # Seeds/ha 9 ,32 1, 137 3, 339 , 430 274 ,39 0 128,049 1 23, 984 191,057 87 ,39 8 13, 465,445 13, 544,7 13 2,871,951 144 ,30 9 286,585 227,642 138 ,211 1 93, 089 17,406,500 11,172,402 3, 976,0 93 154,472 93, 496 38 0,751 217,480 212,052 16,206,746 Manipulated watershed Betula alleghaniensis had the highest seed production per... .291 11.2.5 Analysis .291 Results 292 11 .3. 1 FHM Forest Mensuration Indicator 292 11 .3. 1.1 Trees 292 11 .3. 1.2 Saplings .2 93 11 .3. 1 .3 Seedlings 2 93 11 .3. 1.4 Diameter Size .2 93 2 83 © 2004 by CRC Press LLC L1641_C11.fm Page 284 Wednesday, March 24, 2004 9:17 PM 284 Environmental Monitoring 11.4 FHM Damage and Catastrophic Mortality Assessment... FIGURE 11 .3 Plot design for tree seed production and canopy gap analysis indicators (Adapted and modified from Tallent-Halsell, N.G 1994 Forest Health Monitoring 1994 Field Methods Guide EPA/620/R94/027 U.S Environmental Protection Agency, Washington, D.C.) The six locations around the perimeter (7 .3 m from the subplot center) are at 30 °, 90°, 150°, 180°, 210°, 270°, 33 0°, and 36 0° (Figure 11 .3) 11.2 .3. 2... Trees/ha East Bear Trees/ha A and Y Trees/ha 285 211.5 97.5 48 12b 1.5 15 1.5 0 0 1.5 0 1.5 1 13 787.5 199.5 261 39 75 90 6 3 0 1.5 0 0 0 3 120 798 429 148.5 30 52.5 63 19.5 15 0 0 1.5 0 4.5 3 108 874.5 L1641_C11.fm Page 2 93 Wednesday, March 24, 2004 9:17 PM Efficacy of Forest Health Monitoring Indicators 2 93 TABLE 11 .3 Number of Live Saplings per ha by Species at Bear Brook Watershed in Maine Species Latin... Saplings/ha A and Y Saplings/ha 262.5 6 93. 8 112.5 75 0 0 56 .3 0 1200 187.5 731 .3 37.5 75 56 .3 168.8 18.8 18.8 12 93. 8 2 43. 8 412.5 0 18.8 75 18.8 37 .5 112.5 918.8 Manipulated watershed 11 .3. 1.2 Saplings Sapling species diversity was higher in the reference EB with eight species, followed by A and Y with seven species, and the treated WB watershed with five species (Table 11 .3) The difference in the total number... located 36 0° and 36 .6 m, the center of annular plot 3 is located 120° and 36 .6 m, and the center of annular plot 4 is located 240° and 36 .6 m Within each annular plot is nested a 1/60 ha, fixed-radius (7 .32 m) subplot Within each nested subplot is a 1/750 ha fixed-radius (2.07 m) microplot It is located 90° and 3. 66 m east of the subplot center Also within each subplot are three 1-m2 quadrats The 3 quadrats... 2004 9:17 PM 288 Environmental Monitoring Annular plot 17.95 m Location of tree seed trap 0.5 m south of subplot Subplot 2 14 13 12 Locations of canopy gap analysis measurements around the perimeter of the subplot 11 Subplot 7 .32 m Subplot 1 7 6 5 Subplot 4 28 9 8 10 2 1 3 4 Subplot 3 21 16 15 17 19 18 23 22 27 24 26 25 20 N 33 0° 270° 30 ° Azimuth from subplot center to point 90° 7 .3 m between points... East Bear A and Y 10 2 10 15 .3 17.1 15 .3 Stdv (cm) Acer rubrum Maximum # of Mean dbh (cm) Trees dbh (cm) 2.1 3. 3 1.7 18 .3 19.4 17.4 8 60 42 Acer saccharum # of Mean Trees dbh (cm) West Beara East Bear A and Y 65 26 20 22.7 20.4 26.4 Stdv (cm) 14 .3 12.6 15 .3 West Beara East Bear A and Y a 141 174 99 18.8 19.5 19.4 Stdv (cm) 6.6 6.0 6.4 Maximum dbh (cm) 8.8 6.4 8 .3 39.6 44.7 44 .3 Betula alleghaniensis Maximum... center for a total of seven Annular plot 17.95-m radius Subplot 7 .32 -m radius 2 Microplot 2.07-m radius Lichen plot 36 .6-m radius 1 3 4 Distance between annular plot centers: 36 .6 m ° ° ° FIGURE 11.2 FHM plot design for lichen communities indicator (Adapted from TallentHalsell, N.G 1994 Forest Health Monitoring 1994 Field Methods Guide EPA/620/R94/027 U.S Environmental Protection Agency, Washington, . Soil Terrestrial Fauna Groundwater Sediment Aquatic Micro-Macro- Flora/Fauna Surface Water Wet Dry Wet Dry Dry Wet Short- and Long-Range Sources L1641_C10.fm Page 267 Tuesday, March 23, 2004 7 :31 PM © 2004 by CRC Press LLC 268 Environmental Monitoring . Page 265 Tuesday, March 23, 2004 7 :31 PM © 2004 by CRC Press LLC 266 Environmental Monitoring 1. Gather pertinent site-specific information on (i) the ecosystems of con- cern; (ii) the potential. monitoring questions in the most cost- effective manner. 10 L1641_C10.fm Page 2 63 Tuesday, March 23, 2004 7 :31 PM © 2004 by CRC Press LLC 264 Environmental Monitoring During the 1990s, federal