Geoscience Reference
In-Depth Information
case study a viable and defensible value estimate can be and was developed, despite re-
source and time constraints, and this may well apply in other applications of EBA using
valuation.
The outcome of the analysis described in this section thus far is a figure for overall
percentage contribution of a habitat type towards a service, e.g. 22.0% for shelf mud for
nutrient cycling. The next methodological step is to refer back to the aggregate value es-
shallow mud in UK marine waters in total provides around £286 million in benefits/an-
num for nutrient cycling, and aphotic reef, around £9 million. But these figures are for
total
provisioning. For each of the three MCZ network scenarios (A, G, and J) developed in
work scenario A the percentages are 17.5% and 12.0% for aphotic reef and shelf mud re-
spectively. In the absence of further evidence, it was assumed that the area of aphotic reef
in network scenario A has the average per hectare service provisioning. Around £9 million
split across 10,968km
2
implies the value of nutrient cycling per hectare of aphotic reef is
around £830/hectare. The value of each service/habitat combination on a per hectare basis
was then coupled with the GIS extent data for each of the three networks.
There is a further step, however, in that this is total provisioning in 2008 per hectare.
The coding for impact described above uses this figure. For aphotic reef/nutrient cycling,
the coding was 'H 10 E', i.e. a high impact (50%-89%) from MCZ designation, reaching
a maximum at
t
= 10, and having an exponential trajectory from
t
= 0 to
t
= 10. (This is
equivalent to the bottom curve in
Figure 7.2
.
) The 0.7 extent of impact point in
Figure 7.2
might be replaced with a value for aphotic reef/nutrient cycling of £581 (i.e. 0.7 X £830),
and the area under the bottom exponential curve would then provide the per hectare benefit
stream in monetary terms for MCZ designation/aphotic reef/nutrient cycling.
