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

46 David A. Wardle and Duane A. Peltzer
of terrestrial ecosystems (Vitousek et al. 1987, Lawton 1994, Chapin et al.
1997), and feedbacks between the aboveground and belowground components
are arguably among the most important of these biotic drivers (Wardle
2002).
Development of a thorough understanding of either primary or secondary
ecological succession, and ecosystem restoration, requires specific consideration
of both the aboveground and belowground subsystems, as well as the
nature of feedbacks between them. Although primary successional development
on newly created surfaces, or secondary succession following significant
disturbance events, has usually been studied only with specific reference to the
plant community and the availability of major soil nutrients (Bradshaw and
Chadwick 1980), the reality is that the aboveground and belowground communities
develop in close concert with each other over successional time. Further,
plant species replacement (such as occurs both during primary and secondary
succession) has major effects on soil communities and the ecological processes
that they control (Wardle et al. 1999, Porazinska et al. 2003, Belnap et al. 2005).
Changes in soil communities in turn influence the direction and speed of both
primary and secondary vegetation succession as well as ecosystem productivity
(van der Putten et al. 1993, De Deyn et al. 2003). Knowledge about feedbacks
between aboveground and belowground biota is also crucial to developing a better
understanding of the principles of ecosystem restoration, because facilitating
the recovery of ecosystems requires recognition of the role of these feedbacks
in driving community- and ecosystem-level properties and processes.
In this chapter, we will start by discussing vegetation succession and ecosystem
development in the context of a combined aboveground–belowground approach.
We will then present three case studies in which principles of succession
studied through a combined aboveground–belowground approach are relevant
to the goals of ecosystem restoration: (1) the consequences of human-induced
changes in densities of browsing mammals, with particular reference to deer in
New Zealand rain forests; (2) the ecological impacts of fire in the long-term,
with particular reference to boreal forests of northern Sweden; and (3) the belowground
impacts of invasive, nonnative plant species and their feedbacks
aboveground. These examples will be used to emphasize the importance of
combined aboveground–belowground approaches to understanding vegetation
succession, the ecological role of disturbance, and the restoration of ecological
interactions and processes.
3.2 Successional Development and Aboveground–Belowground
Linkages
An important component of ecosystem development and succession is the
changes that occur in the attributes of the dominant vegetation. As primary succession
proceeds, there is a general shift in dominant plant species from those
that are of small stature, often herbaceous, short-lived, have a high reproductive
output, and produce litter with high quality with those that are increasingly
larger, woody, long lived, more conservative in retaining nutrients, and produce
foliage and litter of poorer quality (Grime 1979, Walker and Chapin 1987,
Wardle 2002). Similar trends also occur in secondary succession, even though
the starting point may be later in ecosystem development because of legacy