Linking Restoration and Ecological Succession (Springer ... - Inecol

140 Karel Prach et al.
We emphasize the role of monitoring in evaluating the success of manipulation
measures against predeterminend restoration targets. Monitoring provides
a feedback by which the restoration program can be modified, and at the same
time deliver information to improve our knowledge of succession.
6.7 Conclusions
Despite some recent progress, unassisted succession and ecologically sound
manipulation of spontaneous succession as a part of restoration projects are
exploited less often than they could be. Technical reclamation using engineering
or mechanical approaches still dominate many restoration projects. In some
cases, we can rely on unassisted succession, which can provide better and
cheaper results than technical reclamation (see Section 6.4.1). That unassisted
succession can take longer to reach the target than technical reclamation is
compensated by the higher structural and functional diversity and higher natural
and conservation value of resulting vegetation.
Whether to use technical reclamation or spontaneous succession, manipulated
or not, may depend on the position of the disturbed site on the productivity
gradient (Fig. 6.6). Numerous case studies (see Section 6.4) indicate that technical
reclamation, usually represented by strong physical manipulation of a site,
is required most often when site conditions are extreme rather than moderate.
At intermediate productivity values, unassisted succession plays a larger role.
Unassisted succession is effective especially if a disturbed site is small and surrounded
by natural vegetation. On the other hand, unassisted succession itself
is not usually a tool of restoration in human managed secondary habitats (see
Section 6.4.2). Continued manipulation of succession in the form of maintenance
management (Bakker and Londo 1998) is essential for the persistence of
the preferred habitats, or succession can be manipulated back to earlier stages.
Preference
unassisted succession
technical restoration
Productivity
Figure 6.6 Preference for unassisted succession and technical restoration changing
along a hypothetical productivity gradient. Unassisted succession is expected to be
the best tool of restoration of moderately nutrient-poor sites (e.g., in stone quarries
and sand pits), where highly competitive species do not expand. While in extremely
unproductive (e.g., toxic) or highly productive (eutrophicated) sites technical restoration
may be preferred, either to ameliorate adverse abiotic site conditions or to suppress strong
competitors, respectively.