9722 - Laserfiche WebLink

Home Browse Search

tI. Wilson 1996, Mitsch et al. 1998) is embraced after the hydrologic conditions are restored. Restoration sites do become revegetated, but may be of different species composition and degree of cover (Seabloom and van der Valk 2003), owing to dispersal limitations of many wetland species (Galatowitsch and van der Valk 1996). Thus, the effectiveness of self-design depends on the restoration goals, but adopting a concept of self-design does implicitly recognize and embrace the existence of multiple end points. An effective restoration of the physical variables will create the template for biotic recovery, but physical structure does not always beget biotic structure, and biotic structure does not necessarily result in similar ecosystem functions across sites. The concept of self-organization, or self-design, is an intuitively appealing approach and is very attractive to resource managers who have limited time and budgets. A self-assembling ecosystem would substantially cut down on the amount of effort required to restore ecosystems, and we feel this is why the Field of Dreams is commonly employed. However, its effectiveness in restoring structure and function is still debatable (Simenstad and Thom 1996, Zedler and Callaway 1999, National Research Council 2001), and restored areas may be quite different from undisturbed sites (Seabloom and van der Valk 2003). In defense of self-assembly, composition of restored sites is expected to approach reference sites given sufficient time (Mitsch 1997). Effective restoration using this approach must overcome issues of recolonization and dispersal, stochasticity in community assembly, and assembly of energy transfer pathways. One commonly used strategy to circumvent these limitations is to jumpstart the process by adding organisms, but our understanding of accelerating ecosystem development is incomplete and may lead to the myth of Fast-Forwarding. THE MYTH OF FAST-FORWARDING The myth of Fast-Forwarding is based on the idea that one can accelerate ecosystem development by controlling pathways, such as dispersal, colonization, and community assembly, to reduce the time required to create a functional or desired ecosystem. This idea stems from the initial floristics model of succession (Egler 1954) in which the process of ecosystem development is accelerated by controlling initial species composition and Ecology and Society 10(1): 19 htto:/ /www.ecolol!.Vandsocietv.orl!lvoII0/issl/artI9/ succession to achieve the desired end point (van der Valk 1998). The major assumption is that we can reliably recreate key processes and links between the biota and physical environment. A driving force behind this approach is the need to demonstrate rapid recovery of disturbed lands in order, for example, to have insurance or mitigation performance bonds returned quickly. Many types of restoration projects justifiably use a fast-forwarding approach to jumpstart the recovery process by using species desired in the ecosystem. As most restorations include plantings to get the ball rolling and stabilize the terrain, it is logical to try to advance the successional process, and this is why the practice is so common. However, relying on the premise that fast-forwarding will produce the desired ecosystem trajectory and speed the recovery process may result in disappointment. Little evidence exists for achieving desired trajectories or functions within the shortened time spans promised by fast-forwarding (Simenstad and Thom 1996, Zedler and Callaway 1999, Campbell et al. 2002, Wilkins et al. 2003). As with other myths, there is some element of truth, and successes using fast- forwarding have occurred (e.g., Clewell 1999). Successful projects typically require multiple plantings and a considerable amount of attention to ensure survival of plantings in systems that may be "premature" for the species' arrival. Even when successful, certain ecological processes, such as the development of tree hollows for cavity-nesting animals, soil development, mycorrhyzal associations, and hydrologic regimes, present more difficult challenges and may take years or decades. Mitsch and Wilson (1996), for example, point out that the 5-year span in which "'quick-fIX' wetlands" are expected to become sufficient replacements for lost or damaged areas is improbably short, and that 15- 20 years is a much more realistic expectation. Long- term monitoring ( 5-15 years) of restoration projects is indicating that a more likely time horizon is several decades for a restoration to resemble a pre- disturbance target (Zedler and Callaway 1999, Wilkins et al. 2003). Many ecological restoration projects--even ecological restoration itself-aim for rapid progress from a damaged state toward some more-or-less specific target. There is nothing inherently wrong with such a goal, however, we should not be so intent on attaining a specific point that the system's potential future state (i.e., after restoration efforts cease and natural processes take over) is ignored.