Have springs restoration projects in the southwestern United States been effective in restoring hydrology, geomorphology, and invertebrates and plant species composition comparable to natural springs with minimal anthropogenic disturbance? (systematic review)
Background
Springs are places where groundwater is exposed at the earth‟s surface, often flowing naturally from bedrock or soil onto the land surface or into a body of surface water. There may be 105-106 springs in the United States, occupying a total area of 500-1000 km2 (less than 0.001 % of the nation‟s land area). Springs, particularly those in arid regions, are vastly more complex, diverse, and productive than are adjacent uplands. At a national and continental scale, springs are among our most threatened ecosystems; in the American West, more than 90 % of springs are estimated to be ecologically impaired (Stevens and Meretsky, 2008). Springs are important ecologically because they provide habitats for a diverse array of aquatic and wetland plant and animal species, many of which are endangered or endemic (Anderson et al., 2003; Springer and Stevens, 2009). Odum‟s (1957) study of Silver Springs in Florida, which laid the groundwork for much of the science of ecosystem ecology, remains one of the few comprehensive examples of springs ecosystem function. In addition, springs are culturally critical landscapes, the focus of profound traditional, religious and ethnoecological attention by indigenous cultures throughout the world (Stevens and Meretsky, 2008).
While some restoration efforts have taken place in arid land springs ecosystems, few have been sufficiently well monitored to evaluate their success. Knowledge of the location, quantity, and quality of a resource is an important first step towards effective conservation and restoration (Thompson et al., 2002). However, the distribution, ecological condition, and threats facing many springs ecosystems are poorly known, and therefore potential restoration needs have heretofore remained unidentified, a gap this document begins to fill. In addition, development and adherence to a springs inventory and monitoring protocol has not been adopted, in part because of the many different jurisdictions under which researchers and land managers operate and a lack of cross- jurisdictional coordination. As more information about springs ecosystems becomes available, there may be compelling evidence to improve stewardship, restoration, and monitoring of these ecosystems. This review examines the state of knowledge of arid land springs ecosystem restoration and monitoring to help springs ecosystem stewards better plan and prioritize management and restoration actions.
Objectives
The objectives of this review are to 1) summarize the state of knowledge about arid land springs restoration, and 2) determine whether springs ecosystem restoration projects in arid regions have been effective in restoring hydrology, geomorphology, and biological assemblage composition and structure in relation to those at natural springs with minimal anthropogenic disturbances.
Methods
A list of search criteria was created to include specific search terms, as well as inclusion and exclusion criteria to help in eliminating irrelevant studies. After relevant literature was found and reviewed, information on study characteristics, methods, and results were summarized in a master spreadsheet. These studies were then analyzed for quality determined from Pullin and Knight‟s (2003) hierarchy of evidence and filtered based on the quality rating. Data from studies considered to be sufficiently robust to meet data quality standards were analyzed as to restoration criteria and success using the Society for Ecological Restoration (SER) International Science & Policy Working Group (2004) criteria for successful restoration.
Main results
Search results and elimination processes returned 15 studies analyzed for this review. The great inconsistency in the rationale for and in the implementation, monitoring, and reporting of springs restoration efforts precluded a meta-statistical analyses of the results. Individual studies were reviewed and results were summarized and analyzed for quality. Restoration success was difficult to assess in most projects because of limited monitoring and follow-up reporting. When restoration success was judged by whether identified restoration objectives were accomplished, most of the studies were rated as successful.
Conclusions
Standardized ecosystem condition and restoration assessment protocols are needed to more clearly understand the success of springs restoration projects, and could be developed through the collaboration of springs restoration stewards. Such a contribution would be highly beneficial to from a conservation perspective and to land resource managers and restoration practitioners. Improved understanding to how specific attributes or characteristics of springs ecosystems respond to specific restoration activities provided in this review will help managers develop rationales, estimate costs, prioritize projects, select appropriate treatments, improve monitoring, and incorporate feedback into future management and restoration activities.
Background
Springs are places where groundwater is exposed at the earth’s surface, often flowing naturally from bedrock or soil onto the land surface or into a body of surface water. There may be 105-106 springs in the United States, occupying a total area of 500-1000 km2 (less than 0.01 % of the nation’s land area). Springs, particularly those in arid regions, are vastly more complex, diverse, and productive than those in adjacent uplands; however, at a national and continental scale, springs are among our most threatened ecosystems, with estimates of ecological impairment in the West exceeding 90% (Stevens and Meretsky 2008). Although Odum’s (1957) studies of Silver Springs in Florida laid the groundwork for much of the science of ecosystem ecology, his study remains one of the few comprehensive examples of springs ecosystem function. Springs are important resources because they are largely non- renewable ecological and cultural resources which provide habitats for a diverse variety of aquatic, wetland, plant and mammal species, many which are endangered or endemic (Anderson et al., 2003; Springer and Stevens, 2009).
While there have been some arid land springs ecosystem restoration efforts (e.g., Anderson et al., 2003; Anderson et al., 2004; Otis Bay, 2006), few have been continually monitored to evaluate their successes. There also still lacks baseline knowledge of many springs ecosystems conditions to determine restoration potential. This lack of knowledge may be a result of the expense of long-term monitoring, or the lack of funding to continue monitoring springs ecosystems after restoration has been completed. In addition, development and adherence to one springs inventory and monitoring protocol has been a challenge for scientists. This is in part because of the many different jurisdictions under which researchers and land managers operate, along with the lack of cross-jurisdictional coordination. Lack of scientific study and conservation has limited the knowledge available to translate to appropriate springs restoration theory and methods. Knowledge of the location, quantity, and quality of a resource is the start toward effective riparian area conservation and restoration in semi-arid and arid regions (Thompson et al., 2002). If more information about springs ecosystems were available, then there may be compelling evidence to promote a greater effort to restore and monitor these ecosystems.
This review aimhopes to resolve deficiencies in the state of knowledge of arid land springs ecosystems restoration and monitoring, thus moving toward a more consistent way of monitoring springs ecosystems. If these issues are left unresolved, it could be detrimental to the future of springs ecosystems and ultimately water resources in arid regions. This review will also be beneficial for the future improvement of restoration and monitoring projects by summarizing the state of knowledge of past restoration monitoring efforts, thus limiting the amount unknown attributes of arid land springs. It will also provide information to help springs ecosystems managers to better prioritize management or restoration actions with generally limited and precious financial resources.