Environmental Engineering Reference
In-Depth Information
based on expected global changes to temperature and precipitation, the likely future distribution
of the ant was predicted. The species is set to contract its range in tropical areas but expand into
temperate areas. Ironically, therefore, the Argentine ant looks set to do less well in Argentina and
South America but become a major pest in North America and Europe. Efforts to eradicate Argen-
tine ants have rarely been successful. The management response is therefore to increase biosecu-
rity precautions in regions expected to become progressively more invadable as climate change
takes hold (Section 11.2.2).
ecology, and whether concerned with conservation, restoration, harvest manage-
ment, pest control, biosecurity or sustainable agroecosystems.
1.3.2
From an
economic perspective
- putting a value on
nature
There is an economic side to every resource management argument. Sometimes this
is obvious to everyone and 'relatively' straightforward to quantify. A decision to
become a player in a fi shery will take into account the costs of buying and maintain-
ing fi shing boats, crew, gear and shore facilities in relation to the value of the sus-
tainable catch. The decision of a farmer to invest in pest control also depends on
weighing up the dollars spent killing pests in comparison to the gains to be made
in extra product at the farm gate. And the economic value of what is put at risk by
the arrival of invaders can be set against the costs of biosecurity border operations
to keep them out.
It can also be relatively easy to work out the cost of saving a species from extinc-
tion - in terms of purchasing a reserve, predator control, and so on. But how can
managers determine the value of the species so they can decide whether the cost is
justifi ed? Then again, you have seen that many economic activities put ecosystem
services at risk (Section 1.2.2). How do we determine the value of lost services so
these can be set against the economic gains associated with the activity? Even the
'straightforward' economics of fi shing and farming turn out to be fraught with dif-
fi culty. This is because traditional economics have not taken into account the associ-
ated environmental costs that are borne by society in general. Take, for example,
the destruction of cold-water coral reefs while trawling, or the reduction in river
water quality resulting from a farmer's indiscriminate application of fertilizer.
Economic valuation of nature is inherently a human preoccupation, being based
on the contributions that biodiversity makes to our well-being. There are also
'deeper' reasons for conserving biodiversity - species may be considered of value in
their own right, a value that would be the same if people were not around to exploit
or appreciate it. But, to be effective, it seems inevitable that conservation arguments
must ultimately be framed in cost-benefi t terms. This is because governments
decide policies against a background of the priorities accepted by their electorates,
and the money they have to spend. The importance of the concept of ecosystem
services, which is relatively new, lies in its focus on how biodiversity provides for
human well-being. Now, economic value can be ascribed to biodiversity in a way
that can be understood by everyone.
A range of techniques are available to put a value on nature. Goods and services
for which there is a market are the most straightforward - values can quite readily
be ascribed to clean water for drinking or irrigation, to fi sh from the sea and medici-
nal herbs from the forest. In other cases, a more imaginative approach is required.
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