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

Chapter 7 Restoration as a Process of Assembly and Succession Mediated by Disturbance 151
trajectories. In addition to concepts of ecological succession, there are other
ecological theories and concepts including assembly and disturbance, which
may be particularly useful when applied to degraded ecosystems that need
restoring. The idea of community or ecosystem assembly arises from the observation
that only certain species are able to establish and survive in any given
area and that species tend to occur in recognizable and repeatable combinations
or temporal sequences. Hence, there is the possibility that a set of rules can be
identified that describe the processes underlying these observations. Temperton
et al. (2004) recently evaluated the broad field of community assembly in relation
to restoration. In particular, the relative merit of different approaches
to assembly were assessed in relation to their direct application in restoration
ecology and practice (Temperton and Hobbs 2004).
We also consider the idea that modifying ecosystem dynamics for restoration
purposes can be done effectively by using disturbance as a management tool,
for instance to set back the successional clock or alter abiotic restrictions for
species establishment and community assembly. Additionally, natural disturbance
events can be used as a “window of opportunity” for restoration purposes,
such as enhancing plant establishment after heavy rainfalls associated with El
Niño in arid environments (Holmgren et al. 2006).
Together, concepts from succession, assembly, and disturbance deal with the
processes by which the living components of an ecosystem change over time
and how the species assemblage present at any one time may be explained.
Our premise in this chapter is that these fields, although often treated as separate
entities, are complementary. Both the similarities and differences between
assembly and succession mediated by disturbance can be effectively assessed
to derive the most promising aspects of the fields for application in restoration.
In this chapter, we thus aim to revisit perspectives from earlier chapters
(particularly Chapters 5 and 6) to consider succession together with assembly
and disturbance, and examine how these mesh together in the context of restoration.
The aim is (1) to discuss the different types of dynamics that potentially
occur in ecosystems—restored or natural, (2) to explore drivers of these dynamics,
including assembly and succession modified by disturbance, and (3) to
illustrate the relevance of these concepts to restoration management.
7.2 Ecosystem Dynamics
A broad categorization of the different types of dynamics that have been hypothesized
to occur in ecosystems includes: deterministic dynamics, stochastic
dynamics, and transitions among alternative stable stables (multiple equilibria).
These are illustrated in Fig. 7.1. Essentially, an assumption of deterministic dynamics
(Fig. 7.1a) suggests a predictable path of development given any particular
starting point, regardless of conditions prior to or during the development
of the ecosystem. This characterizes the traditional Clementsian perspective
(Clements 1916), as later characterized in ecosystem terms by Odum (1969).
Stochastic dynamics (Fig. 7.1b) suggest a less orderly development with the
path of development constantly being affected by a variety of factors each
working on a range of different temporal and spatial scales, resulting in an
apparent random path. Finally, a state and transition approach (Fig. 7.1c) suggests
that development is phasic and characterized by relatively sudden changes