The Term Restoration Is Used in Different Ways; However, It Can Be Defined As, The

Introduction

For several decades, ecologists and scientists alike have been working toward developing and improving scientifically defensible stream riparian and wetland assessments (Stevenson 2002). These assessment tools provide a definitive procedure for evaluating the complex ecological condition and functional capacity of an ecosystem using a finite set of observable field indicators (Brinson et al. 1996; Kleindl et al. 2009). They are aimed provide information to fulfill permitting requirements, satisfy water quality standards, and guide management and regulatory decisions. The selection of assessment methods depends up on the objectives, geographic area, wetland type, desired level of detail, and availability of applicable models. More importantly, the results of assessments can be translated into restoration designs and implementation along with long – term monitoring protocols (Kleindl et al. 2009).

The term restoration is used in different ways; however, it can be defined as, the “reestablishment of the structure, functions and natural diversity of an area that has been altered from its natural state” (Pess et al. 2003). Cortina et al. defines restoration in terms of the simultaneous increase of the structure and function in an ecosystem due to human intervention. In ecological restoration, the structure and function are considered attributes of the whole ecosystem. Structure might refer to the geomorphology, hydrology, soil, water quality, and vegetation. Functions might refer to the services they provide such as detaining flows, groundwater storage and recharge, filtering pollutants, food webs, plant succession, and diversity of aquatic habitats ( …citation here). The loss of ecosystem services provided by naturally functioning river systems is a worldwide problem caused by pollution, loss of habitat structure, loss of access to habitat, and invasion of exotic species (Costanza 2000). Ecological assessments are generally useful in determining whether the function of a system is impaired to the point that restoration is necessary (Stevenson 2006).

In the United States, billions of dollars are being spent on stream and river restoration (Palmer et al. 2005; Bernhardt et al. 2005). Yet, the outcome of river restoration are marked by inadequacies that applied the wrong spatial scale to understanding the complexity and dynamic nature of ecosystems and their attributes (Beechie 2008; Hauer and Lorang 2004). Hauer and Lorang argue that processes that occur at a landscape scale are largely driven by both structure and function. However, restoration efforts are typically directed toward site-specific scales such as a specific wetland or toward a single-species. Successful restoration of river ecosystems and their physical, biological and chemical integrity require innovative management approaches that consider the appropriate spatial and temporal scales of their variability and the anthropogenic impacts. (Kerans and Karr, 1994; Hauer and Lorange 2004)

This paper sets out to examine assessment techniques directed toward river restoration, including wetland and riparian systems, and its role in systemically gathering information for achieving improved management decisions and effective restoration strategies. Approaches including the functional capacity assessments, biological assessment, as well as rapid assessment methods will be discussed. An overview of existing rapid assessment methods (RAMs) and technical considerations that have been developed for use in state and tribal programs will be provided. Although most of the literature reviewed for RAMs are specific to wetland ecosystems they are applicable to floodplain and riparian systems. Consideration of post-restoration techniques including monitoring and adaptive management will also be discussed.

Scales of Assessment

Although assessment methods vary in quantitative detail of the data collection, the level of scale at which assessments are performed has considerable effects on the resolution of the results (Kleindl et al.2009). The ability to accurately assess ecological function is complicated by the fact that wetlands vary in type, in time and in space, which directly influences their functional ability. Numerous assessment techniques have been implemented on a variety of spatial scale and intensity (Sutula et al. 2006) (Figure 1). The intensity of the methods range from complex and time –intensive (e.g. HGM) to quick and relative qualitative (e.g. rapid assessments); while, the spatial scale can vary from the watershed level (e.g., Landscape Level Functional Assessment [LLFA]) to site-specific (e.g., Index of Biotic Integrity [IBI]). Assessments conducted on a regional-scale tend to generate coarser results since it does not develop the assessment models necessary to be applied rapidly in the field while be sensitive enough to detect changes in function at the appropriate level of resolution (Kleindl et al. 2009).

Figure 1. Plot of intensity of assessment versus scale of assessment (after Sutula et al)

Recognizing the spatial extent of the assessment is important to establish as riparian and wetlands exhibit distinct characteristics. Although wetlands share these characteristics, they also perform on a wide range of geologic, climate, and physiographic situations (Brinson 1996). This variability poses a challenge to developing assessment methods that are practical for end users to conduct in a short period of time and accurate in that the method can detect significant changes in function.

It is important assessments distinguish factors effecting variability. River systems are not static. Variability can occur as part of a natural cycle, from diurnal to seasonal fluctuations. For example, dissolved oxygen varies diurnally in response to the photosynthetic activity of plants producing oxygen. Variability can also occur due to anthropogenic activity such high aquatic plant production (e.g. algal blooms) in response to nutrients from runoff or sewage. Errors in sampling or analysis can also attribute to variability of the assessment (Reed 2003).

Reference site

Assessment methods should include reference conditions. These “reference conditions” serve as benchmarks which assessment scores for the study area can be compared against (Reed 2003; Brinson; 1993; Palmer et al. 2005; Pess 2003; Hauer et al. 2003). The reference site should also include a range of variation in condition across a gradient of disturbance from most disturbed to least disturbed (Brinson 1996; Reed 2003). Palmer et al. (2005) stated that in order to frame restoration goals reference sites should be selected to represent the waters in the absence of or relatively undisturbed by human impacts. Identifying reference sites for large river systems poses challenges since the upper reach might be less impacted than the lower reaches. Thus, choosing a heavily impaired river reach as a reference condition to “move away from” might be a practical approach in some cases.

Assessment endpoints

Some methods are developed to assess function. Function is defined as an ecological process occurring over time or more simply, “the processes that wetlands do.” (Smith et al. 1995). Identifying function requires repeated measures that quantify rates of processes over time. There is a distinction between methods that assess condition versus those that measure function. Functional capacity assessments often focus on the capacity to perform individual functions and provide more detailed information, while the condition-based assessments produces a general evaluation that combines multiple functions and provides the overall ecological health of a system based on the combined scores (Hauer et al. 2003). The type of approach should be clearly defined and based on management questions being investigated (Brinson 1996; Stevenson and Hauer 2002).

Assessment goals and objectives

Identifying the goals and objectives of an assessment aimed to restore a system must be clearly defined and realistic (Palmer et al 2005; Dahm et al. 1995). Often times, managers tend to define restoration goals as mimicking historical site conditions when the historical setting of the area is unknown. Palmer et al. (2002) argue that rather than trying to reach for unachievable conditions the goal should support minimal degradation of the river while achieving the most ecologically dynamic state possible. An ecologically dynamic state is one in which the biological, hydrological and geomorphic features of the natural system vary in abundance and composition both spatially and temporarily, as in reference sites. An ecologically dynamic state also implies that these natural systems are resilient to outside disturbances.

Assessment Techniques

Numerous assessment techniques that characterize the current state of natural systems have been developed for varying purposes but with the ultimate goal of managing and restoring ecosystems. A variety of protocols have different approaches that range from subjective and visual-based to objective and quantitative-based (EPA 2004). This paper compiled various assessments developed by agencies with specific assessment goals and intent (Table 1). However, only a few select methods will be discussed.

The Natural Resources Conservation Service (NRCS) has developed the Site Assessment and Investigation and Stream Visual Assessment (VA) Protocols. They provide a multidisciplinary inventory and assessment for stream restoration (NRCS 2007). The process-based framework assesses the past, present, and future states of watershed dynamics, identifies resource needs to support the selection and design of restoration activities, and measures the outcomes and successes of restoration activities. The VA assessments assist in the pre – and post – assessment of restoration by evaluating: dominant fluvial processes, anthropogenic impacts to fluvial systems, and the status of restoration designs. The assessment protocols have been helpful for landowners to implement channel stabilization structures (NRCS 2007).

The NRCS technique collectively assesses the hydrologic, geologic, and biological attributes of a stream system. An initial assessment of the stream flow duration and classification is based on field criteria such as channel, flow duration, bed water level, aquatic insects, material movement, channel materials and organic material. Changes in sediment supply in the system, sediment transport, change in bank erodibility, or a combination of these factors determine whether a channel is stable or unstable. The biological component records the presence of pools and riffles in order to assess the potential of fish productivity. NRCS assessments are flexible and often incorporate two common biological indices, the Index of Biological Integrity (IBI) and the Ephemeroptera, Plecoptera, and Trichopera (EPT) Index. The IBI utilizes fish surveys to assess anthropogenic impacts on a stream and its watershed (Kerans and Karr 1994). Since fish are sensitive species to an array of stresses and their population demonstrates effects of reproductivity failure or mortality, they are useful in measuring degradation in watersheds. The EPT index uses bethic macroinvertebrates (e.g. mayflies, stoneflies, and caddisflies) as indicators to assess land use and water quality within a watershed. The bottom-dwelling organisms serve as indicators of the effects the immediate area they are found. The EPT index is based on the grounds that the greater the impacts (e.g. pollution) the less the species richness is found, as only a few species are tolerant to pollution. The biological methods mentioned above are commonly used in assessment protocols and in completion with the reference condition approach (Bowman and Somers).

Integrated ecological assessment (IEA) is another assessment technique developed by Stevenson (2006). Not only does the IEA method assess the biological condition of attributes in the ecosystem it can detect pollutants and anthropogenic activities that may be the cause of problems. Examples of biological (structural) attributes that can be measured and assessed include aquatic macrophytes, algae, and aquatic insects (Stevenson and Hauer 2002). The IEA uses algae as a key indicator since they serve as an important component of food webs in most aquatic ecosystems. Excessive buildup of algal biomass alters the system by depleting the dissolve oxygen available, changing the habitat structure for fish and aquatic invertebrate, and diminishing the aesthetics of drinking water supplies, and producing a toxic by-product substance. Algae biomass is measured by sampling chlorophylla, cell densities, and cell volumes or by direct visual assessment (Secchi disk and rapid periphyton surveys). Diatoms are commonly used in these assessments than green algae or cyanobacteria due to their quick identification and dominant presence.

On the broader spectrum, a landscape scale assessment offers an assessment of stream channel and in support of riparian habitat restoration needs (Meixler and Bain 2009). This quantitative assessment technique uses spatial analysis tools to efficiently assess stream quality and identifying priorities for conservation management. Changes in stream and riparian health can be determined using GIS rather than traditional field methods. This assessment is intended to be cost-effective and rapid, and can be readily updated. The study evaluated the East Credit subwatershed in Ontario, Canada which had impaired water quality and degraded stream channels, thus targeted for restoration practices. Land cover data, digital elevation models (DEMs), road shapefiles, railroad shapefiles, 1:100,000-scale streams and drainage delineates were compiled for each reach. A stream channel condition index (SCCI) was calculated using information on land cover, road and railroad density, and sinuosity while the riparian condition index used estimates of percent forest, and vegetation patch density based on land cover in the floodplain. Each reach was classified in restoration classes based on the indices and the results of the model land ownership, slope, position in the subwatershed, and adjacency to high-quality habitat. The priority ranking from the GIS model was compared with the field based classification and the GIS-based method generated fairly accurate results. The Skagit Watershed Council also incorporated GIS analysis to conduct assessments by estimating changes in sediment supply due to land use by extrapolating from sediment budgets in select tributary watersheds in northwestern Washington State. The method resulted in identifying sediment supply classes as either similar to the natural background rate, or significantly higher than the background rate due to land use activities.

Table 1. Varying assessment techniques developed with varying indices measured

Assessment Technique / Assessment developer/champion / Indices measured
Stream Restoration and Investigation – Site Assessment and Investigation; Stream Visual Assessment Protocols / NRCS / Hydrological, Geological, Biological
Integrated Ecological Assessment / Stevenson. / Biological (algae assemblages)
Ecological Impact Assessment
Landscape Scale Assessment / Meixler and Bain / Hydrological and geological
Rapid Bioassessment / U.S. EPA / Biological
Stream Corridor Assessment Survey / Maryland Department of Natural Resources / Instream and near-stream habitat conditions
Rapid Stream Assessment Technique
Environmental Methods Assessment Program (EMAP) / U.S. EPA
Proper Functioning Condition Assessment / U.S. Bureau of Land Management, U.S. Forest Service, NRCS / Riparian health
Breeding Land-Bird Assessment/Biotic Integrity / Terrell D. Rich
Benthic Index of Biotic Integrity (B-IBI) / Kerans and Karr / Assess biological condition using invertebrate assemblages
Rapid Stream-Riparian Assessment (RSRA) / Stevens, Stacey, Jones, Duff, Gourley and Catlin
Lotic Wetland Health Assessment for Streams and Small rivers / Bureau of Land Management
Riparian Assessment for Lotic Systems / Montana Natural Resource Conservation Service
Greenline Bank Stability / US Forest Service
Landscape Level Functional Assessment / US Army Corp. of Engineers
Hybrid Assessment of Riparian Function
Integration of Hydrogeomorphic and and IBI / Stevenson and Hauer
Benthic Assessment of SedimenT (BEAST) / Biological

Rapid Assessment Methods

Alarmed by the diminishing water quality of the nation's streams and lakes, as well as the degradation of wetlands and the valuable benefits they provide, the Federal Water Pollution Control Act of 1972 was enacted. This legislation later became the Clean Water Act (CWA) and included requirements to improve water quality and specific limitations on the development of wetlands. Through this act, wetlands turned out to be the only land type to be regulated on both private and public lands within the United States (EPA 2004; Stevenson and Hauer 2002). In 2008, the Environmental Protection Agency and Army Corp of Engineers released a rule that advocated the use of functional assessments in mitigation monitoring and performance evaluation. With that ruling came the need for rapid assessments that would assess wetland and riparian function.