Environmental Engineering Reference
In-Depth Information
pervasiveness of human infl uence in the world's
oceans, with 41% being classed as experiencing
medium-high impact (Halpern
et al
. 2008 ).
Hence the future holds many challenges for ecosys-
tem management given the rapidity and extent of eco-
system change, the uncertainty surrounding likely
redistributions of species, and the formation of novel
assemblages that also lead to new sets of interactions
among species. The implications of these challenges
and potential approaches to dealing with them are out-
lined in the next section.
measure in order to check on progress. Much conser-
vation management aims to maintain current assem-
blages or species populations in particular places,
particularly nature reserves, while ecological restora-
tion often takes historic or current
reference systems
as the basis for setting restoration goals (Jackson &
Hobbs 2009; Cole & Yung 2010). A key element of the
discussions mentioned above on climate change and
other environmental changes is that the future may be
quite unlike the past or the present.
Currently in the conservation and restoration litera-
tures, there is much debate concerning how rapid envi-
ronmental change might or should alter how goals are
set. Are historical ecosystems still valid points of refer-
ence on which to base conservation and restoration
goals? Should we focus on past and present species dis-
tributions if, in all likelihood, these might be dramati-
cally different in the next few decades? Restoration
projects, in particular, are at the forefront of decision-
making discussions, and increasingly prominent in the
politics and legislation related to attempts to slow and
mitigate anthropogenic climate change. How much
should project managers aim to maintain or restore
systems that are likely to be resilient in future climates
rather than systems which mimic past states? Should
we even set targets at all, or should we simply let the
system take whichever course matches the changing
situation? Should species selection be made on the
basis of local species and populations or should a mix
of species from different environments and locations be
used to bet-hedge against future changes? To date,
there is a lot of discussion (e.g. Broadhurst
et al
. 2008 ),
but no clear answers to these questions.
3.4
ECOSYSTEM INTERVENTIONS
Deciding if and how to intervene in ecosystems in a
rapidly changing world is one of the major challenges
facing humanity in the twenty-fi rst century. Clear
enunciation of goals, identifi cation of the various
options for intervention and successful intervention at
key leverage points will be essential for the effective
conservation, management and restoration of the
world's ecosystems and the services they provide
(Hobbs & Cramer 2008 ; Hobbs
et al
. 2011 ). Many dif-
ferent management interventions are possible, ranging
from no active intervention, through activities such as
removing invasive species, to large-scale engineering
works such as removing dams from rivers or reinstat-
ing hydrologic fl ows in whole river systems. Deciding
on the type and extent of intervention is partially based
on the identifi cation and diagnosis of degradation or
dysfunction in a system and an accompanying analysis
of likely costs, benefi ts, and likelihoods of success.
However, social and value-based judgements are also
important, and decisions to intervene in particular
ways may be made on the basis of current social
norms, valuation of particular species or ecosystem
states over others and so on.
3.4.2
Conserving species and assemblages
Heller and Zavaleta (2009) reviewed two decades of
scientifi c literature on recommendations on
biodiver-
sity
management in the face of climate change. They
suggested that adaptation to climate change broadly
requires improved regional institutional coordination,
expanded spatial and temporal perspectives and incor-
poration of climate change scenarios into all planning
and action. In addition, a greater effort is needed to
address multiple threats and global change drivers
simultaneously in ways that are responsive to and
inclusive of human communities. Interestingly, the
same recommendations could also be made about
making conservation efforts more effective in general.
3.4.1 Setting goals and targets when
everything is changing
Deciding on goals is an important ingredient in the
development of effective management and restoration
programmes, and yet such goals are often poorly artic-
ulated or else are presented in broad terms that have
little relevance in any particular situation. Without
clear goals and targets, it is impossible to tell manage-
ment outcomes are being achieved or to decide what to
