Environmental Management and Restoration in a Changing Climate - Restoration Ecology: The New Frontier - page 25

ered. Particularly since management and policy need
to take into account not only biophysical attributes but
also social, economic and political factors, considerable
uncertainty surrounds the management and policy
responses to climate change. How, for instance, do
national and state governments devise policies to
deal with rapidly changing environmental and socio-
economic aspects? And how does a manager of a
nature reserve decide on management options that will
carry his or her reserve through an uncertain future?
Although policy documents may be drafted to portray
a relatively certain response, there is always likely to be
incomplete knowledge and understanding embedded
in the assumptions on which the management and
policy rests.
Recognizing that different levels of uncertainty exist
can help clarify otherwise confusing debates. On one
hand, endless discussion on things for which there is
a fair degree of certainty can be short-circuited. On
the other hand, dogma or vested interest can be pre-
vented from dominating in arenas where considerable
uncertainty persists. For the practice of restoration
ecology , the uncertainty cascade indicates that
climate change defi nitely needs to be considered in
planning and management of restoration projects but
that there may be considerable uncertainty surround-
ing different approaches and likely outcomes. These
issues are discussed further in subsequent sections.

humans are changing the planet discussed above lead
to complex and profound changes in ecosystems. In
the past, ecosystems exhibited a range of characteristic
dynamics, mostly within a bounded state space. This
state space has been termed the historic range of varia-
bility , a concept that is frequently used to defi ne con-
servation and restoration goals and targets (Landres
et al . 1999). However, human alteration of the abiotic
environment and changing biotic composition because
of local extinctions and the advent of introduced
species can, and does, shift ecosystems into new con-
fi gurations with respect to what was present histori-
cally. These novel ecosystems are characterized by
new species combinations and/or signifi cantly altered
abiotic conditions (Hobbs et al . 2006, 2009 ). While the
existence of such ecosystems has been discussed for
several decades, they have been relatively little studied,
and the implications for management and restoration
have only recently been considered (Seastedt et al .
2008). Markedly differing dynamics may be apparent
in novel systems (Mascaro et al . 2008), but in some
cases it appears possible to alter assemblages in par-
ticular directions through either facilitating natural
processes or active management (Abelleira Martínez
2010 ; Kueffer et al . 2010). Particularly where the
novel assemblage includes non-native species, there is
valid concern that conservation goals may be compro-
mised (Simberloff et al . 2011 ; Vince 2011 ), although
there is also the potential for novel systems to provide
useful ecosystem services.
The need to consider how to manage signifi cantly
altered ecosystems has become increasingly apparent
as recent estimates indicate that about 80% of the
Earth's land surface is modifi ed by humans in some
way, with perhaps 40% qualifying for description as
' novel ' (Ellis & Ramankutty 2008 ; Marris 2009 ; Ellis
et al . 2010). These estimates arise mostly from land use
modifi cations. When climate change is considered,
there is the additional likelihood that some areas will
experience climate conditions for which there are
no current analogues (Williams & Jackson 2007;
Williams et al . 2007). In addition, as species respond
individualistically to climate change, new species
assemblages are likely to form (Jackson et al . 2009 ;
Stralberg et al . 2009). Because it is impossible to model
species distribution shifts into climate spaces for which
there is no current analogue, it is very diffi cult to
predict with any accuracy the future species combina-
tions in such areas (Fitzpatrick & Hargrove 2009).
Equivalent analyses for marine systems also suggest a

3.3 NOVEL ECOSYSTEMS

A feature of the development of ecology over the past
few decades has been the incorporation of dynamism
and change as a key feature of most ecosystems. From
a rather static view of ecosystems as equilibrium enti-
ties which stayed the same or had predictable recovery
patterns from disturbance back to that equilibrium,
ecology now recognizes that ecosystems are dynamic
at a wide range of spatial and temporal scales (see
Chapter 6). Long-term climatic shifts cause ecosystems
and their components to shift across landscapes and
continents. Disturbances of varying scale and inten-
sity set ecosystems on complex paths of recovery,
and sometimes complex feedback mechanisms cause
alternative states to form and persist (Botkin 1990;
Scheffer 2009 ).
As humanity ' s infl uence on the planet grows, the
extent to which human activities modify ecosystem
dynamics also grows. The various ways in which