Challenges in using valuation in ecosystem-based management in a marine context: the case of UK Marine Protected Area designation - Ocean Sustainability in the 21st Century - page 253

ther, the methodology developed for allocating the total value across habitat types is some-
what coarse. The assumption of heterogeneity in terms of equal provisioning across each
hectare of a particular habitat type is also clearly a simplification, and this is an example
of interrelatedness between the science and the economics, which in this case could not be
dealt with.
Another example of this interrelatedness is the issue of linearity. Although the traject-
ory over time towards the final assumed 'plateau' of ecosystem service provisioning can be
coded as non-linear (i.e. exponential or log), it is assumed that if the maximum extra pro-
visioning is +70% compared with BAU then this is twice as valuable to society as +35%.
The contribution of Barbier et al . ( 2008 ) is significant in this regard as it explicitly focuses
on non-linearity in coastal mangroves, salt marshes, and other marine ecosystems. The au-
thors argue that service provision does not 'scale up' uniformly with a change in habitat
extent.Inthecaseofmangroves,provisioningoftheecosystemservice,termeddisturbance
prevention and alleviation in the MCZ study (or storm buffering), the service provisioning
is lowered as successive landward zones of a mangrove forest are crossed. Such potential
non-linearity is assumed not to apply in the MCZ study, although it is likely to be present.
Arelatedissueistheoccurrenceofthresholdeffectswhereinatippingpointisreached
that implies an abrupt shift to a new ecosystem steady state. This discourse can be linked to
the concept of safe minimum standards (TEEB, 2010 ) . The problem in bio-economic ana-
lysis is that it is extremely difficult to define safe minimum standards, in the same way that
there is considerable uncertainty in terms of the definition and evaluation of Good Envir-
onmental Status in the MSFD. With respect to the MCZ case study, the issue of threshold
effects is likely to be ofless concern as the valuation pertains to a management intervention
that increases serviceprovision,andthereinreducestheproximitytoecosystemthresholds.
The cost report (ABPMer, 2007 ) does implicitly consider reductions in ecosystem service
provisioning, e.g. reduced seafood as a provisioning service owing to MCZ designation.
This would, however, also potentially move the system away from a tipping point (the col-
lapse of a fishery owing to overfishing) unless there were a displacement effect, i.e. fisher-
men redirecting and redoubling fishing effort in non-protected areas.