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preferable to avoid the need for interventions to support speci
ed sources
of an ecosystem
s resilience that may themselves have negative consequen-
ces by doing what we can to keep ecosystems away from thresholds in the
'
rst place. 76
2.3.2 What makes an ecosystem generally resilient?
General resilience concerns the ability of systems to
'
absorb disturbances
of all kinds
including those due to unexpected events, and to phenom-
ena that are expected (such as climate change), but for which the scale
of disturbance and consequences are unknown. 77 It also provides cover
for our ignorance of the structuring variables of ecosystems and their
thresholds, and for the unanticipated effects of interventions into eco-
systems. The speci
'
ed resilience of ecosystems to particular risks con-
tributes to their general resilience. However, it is otherwise dif
cult to
locate general resilience in speci
c components of ecosystems. The fact
that systemic properties are the product of highly complex interrelation-
ships between the biotic and abiotic components of ecosystems makes
it impossible to identify the sources of a system
s resilience with preci-
sion, whilst the reliability of any snapshot of key components will reduce
over time because of systemic dynamism.
In view of these dif
'
culties, commentators on general resilience tend
to equate this property with the possession of certain attributes that are
collectively thought to enhance the ability of ecosystems to withstand
disturbance. 78 The diversity of species that a system contains provides
'
for its ability to retain its existing state in the event that
species that perform systemic functions are lost. The existence of sub-
components within systems which, whilst they are connected, are not
tightly linked (
insurance
'
) enhances the capacity of ecosystems to
reorganise in the face of disturbance. The existence of corridors between
biodiverse hotspots enables the interchange of biotic communities
'
modularity
'
76 Walker and Salt,
'
Resilience Practice
'
,p.100.
77 Walker and Salt,
'
Resilience Practice
'
,pp.90
-
1, 185
-
9; Folke et al.,
'
Resilience Thinking
'
,
under
'
General and Speci
ed Resilience
'
; Carpenter et al.,
'
General Resilience
'
,3250
-
1.
78 Walker and Salt,
'
Resilience Thinking
'
, pp. 121
-
2; Walker and Salt,
'
Resilience Practice
'
,
pp. 92
-
8; Carpenter et al.,
'
General Resilience
'
,3251
-
3; H.M. Leslie and A. P. Kinzig,
'
in K. McLeod and H. Leslie (eds) Ecosystem-based Management for
the Oceans (Washington, DC: Island Press, 2009), pp. 62
Resilience Science
'
-
5; S. A. Levin and J. Lubchenco,
'
Resilience, Robustness, and Marine Ecosystem-based Management
'
(2008) 58 BioScience,
30
-
1; R. Biggs et al.,
'
Toward Principles for Enhancing the Resilience of Ecosystem Services
'
(2012) 37 Annual Review of Environment and Resources,421
-
48.
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