Wetland restoration: The potential for assembly rules in the service of conservation

Abstract

One of the pressing problems for applied ecologists is the efficient restoration of structure and function to degraded ecosystems. Where some other conservation activities, such as protection of existing wilderness, continue to require making the best of increasingly bad situations, the goal of restoration raises the pleasing prospect of measurable improvement in landscapes. Restoration simultaneously provides the ultimate test for the discipline of community ecology: ecologists should be able to build an ecosystem in the same way an engineer builds a bridge, with a list of parts connected in specified ways leading to certain reliable outcomes. Failures would reveal that scientists do not adequately understand the system. Practical considerations suggest the application of tools that already exist rather than the invention of new ones. The objective of this paper is to suggest that two valuable tools may already exist, tools that provide an intellectual foundation for restoration ecology. Such a foundation is necessary because there has been a tendency for restoration ecology to represent a haphazard collection of individual cases rather than a well-defined discipline with repeatable methods. One possible scheme for unifying studies of restoration is that provided by assembly rules, where predictions are based upon key environmental factors and the responses of species to those factors. The potential of such assembly rules is introduced using three examples: fish in wetlands, plants in salt marshes, and plants in prairie potholes. I then describe an experiment where a standard species pool of wetland plants was sown into twenty-four different sets of environmental conditions, illustrating how landscapes can select communities out of larger pools. A second possible tool is indicators of ecosystem integrity. These can measure whether a project actually works. Clear discrimination between success and failure can improve restoration procedures by accelerating the evolution of management principles and techniques; Holling has called this process 'adaptive environmental assessment.' I conclude with the optimistic view that restoration already has the tools for continued progress; what is needed is primarily their intelligent application. That is, rather than ending with a typically academic plea for more research, I suggest (for a change) that what is needed is only the discriminating application of procedures and principles that already exist.

The ecology of restoration: historical links, emerging issues and unexplored realms

“…Given the modernity of this debate within restoration ecology, this research shortfall is not surprising, and we may expect more publications in the near future. The restoration and creation of vernal pools (Collinge 2003) and prairie potholes (Keddy 1999;Seabloom & van der Valk 2003) may be ideally suited to this kind of research, because of their discrete nature and potential for multiple independent replicates.…”

Functional trait differences between extant exotic, native and extinct native plants in the Hunter River, NSW: a potential tool in riparian rehabilitation

“…However, they also warn that resilience, measured in terms of species composition, can easily be affected by perturbations and is subsequently difficult to assess in frequently disturbed riparian systems. A further problem with measures of taxonomic structure is that although they are easy to collect and process and often involve relatively low costs (Keddy and Schlieder, 1999), they are not necessarily indicative of changes underlying ecosystem structure or function (Brooks et al, 2002). Conversely measures of ecosystem functions, while valuable indicators of system processes (Bunn et al, 1999), can be expensive and time consuming to collect.…”

Identifying wetland compensation principles and mechanisms for Atlantic Canada using a Delphi approach

“…Consistent application of these requirements would facilitate compliance efforts and would greatly increase NJDEP's ability to measure the success of such efforts in achievement of programmatic and/or NEPPS goals. The setting of clear, realistic goals prior to the implementation of a mitigation project may also increase chances of success (Ehrenfeld, 2000;Keddy, 1999 Although this mitigation site was generally consistent with approved plans in terms of design, the site failed to achieve wetlands due to inadequate hydrology. Inadequate hydrology was a major contributing factor to low Wetland Achieved scores.…”

“…For example, if observable indicators of hydrology are present such as drift lines, hummocks, and/or plant morphological adaptations, it is assumed that the wetland has the potential to perform hydrologic functions analogous to a natural wetland of the same type. For examples of predictors of wetland function, see Adamus and Stockwell (1983) and Keddy (1999 and.…”