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

170 Richard J. Hobbs et al.
8.3 Where Is Restoration Done?
The “Where?” question is partly tied up with the “Why?” question. What sort
of ecosystem or landscape are we dealing with and what successional stage is
it in? Is the landscape old and does it need to be stabilized before it becomes
irreversibly damaged? Is it a natural area where the management focus is on
conservation, or is it a production landscape in which the primary focus is
agriculture or forestry? Has the area been severely modified through mining or
urbanization, or is the area simply in poor condition through mismanagement
such as overgrazing? In other words, is the situation more akin to the relative
infertility of the initial stage of primary succession or to secondary succession
where a biological legacy remains? Studies of disturbance regimes and ecological
succession can both help clarify answers to these fundamental questions.
Also involved in the “where?” question is the size of area being considered.
For example, in Chapter 4 we see that the visual symptoms of salinity can
be confined to a relatively small patch, but restoration is needed at a broader
landscape scale, perhaps even across regions or state boundaries. Is it possible
to consider single patches in isolation, or do we need to consider the broader
landscape context in which the patches sit? For instance, if we are working
with a degraded, semiarid woodland in Australia, is putting a fence around
the woodland to reduce grazing pressure (as discussed in Chapter 3) going to
be sufficient to restore the area, or do we need to deal with the broader landscape
processes such as hydrological imbalance which might also be threatening the
woodland (Cramer and Hobbs 2002)? In addition, dealing with particular problems
in one location may lead to unintended impacts elsewhere; for instance,
managing for salinity by increasing drainage in one area may lead to deleterious
impacts downstream (Chapter 4). Similarly, using aggressive, fast-growing
plant species as “pioneers” which rapidly colonize degraded areas may result in
the species spreading into the surrounding landscape and becoming a problem
weed (Parmenter et al. 1985, Sukopp and Starfinger 1999). Again, successional
concepts can help plan appropriate restoration actions. Useful knowledge about
local seed inputs and their dispersal mechanisms, species growth requirements
and their interactions, and ecosystem impacts of focal species can be gleaned
from successional studies, particularly if those studies have been conducted in
similar habitats (see Chapter 2). Succession can also offer insights into likely
outcomes on old landscapes (see Chapter 4), or help identify situations where
unaided succession is the best restoration approach (see Chapter 6).
8.4 What Is Being Restored?
What to restore is one of the key questions in restoration projects, but it is often
poorly addressed. Clear definition of the problem being tackled and the goal or
end-point being considered is essential for the successful conduct and completion
of restoration projects (see Chapter 1, Hobbs 1999). Successional studies
can help decide what a restored ecosystem might “look like” but prediction can
be inaccurate (see Chapters 2 and 7). Often the information comes from nearby
“reference systems” or historical data to decide what the system was previously
(Egan and Howell 2001; see Chapters 3, 4, and 7). These approaches
generally consider the structural or species richness aspects of the system,
whereas in many cases the functional aspects of the substrate are easier to restore