Introduction – humans, nature and human nature - Ecological Applications: Toward a Sustainable World - page 13

One obvious management response to habitat loss is to protect as much as possible
of what remains, and to include in a network of reserves examples of the variety of
natural habitats that exist. In fact, protected areas of various kinds (national parks,
nature reserves, sites of special scientifi c interest, etc.) grew both in number and
area during the twentieth century. But only about 7.9% of the world's land area is
protected (and 0.5% of sea area - Balmford et al., 2002) and, moreover, there is
the disturbing fact that most large reserves are on land that no one else wanted
(Figure 1.10).
Protection of wilderness is important and, in one sense, 'relatively' easy to achieve.
This is because wilderness is inhospitable to humans and therefore diffi cult to
exploit. (But threats emerge if valuable minerals are discovered in such pristine
settings.) However, distributions of endangered plant and animal species sometimes
overlap with human population centers. To conserve maximum diversity, it follows
that greater focus must be placed in future on areas of higher human value. A global
trend toward reduced government subsidies for agriculture and the lowering of
international trade barriers may have fortunate consequences for the protection of
biodiversity. Thus, in Europe, North America and elsewhere, 'marginal' agricultural
land is becoming increasingly uneconomic to farm. Mass-membership organiza-
tions, such as the Wilderness Foundation and the Royal Society for the Protection
of Birds, have been responding to the opportunity by purchasing some of this land
for 're-wilding'. The restoration of biodiverse grasslands and woodlands will add
somewhat to the total area of the world that is protected for biodiversity.

1.2.5 Invaders -
unwanted biodiversity

Travel has boomed, the world has shrunk and, just like people, plant and animal
species have become globetrotters, sometimes transported to a new region on
purpose but often as accidental tourists. Only about 10% of invaders become estab-
lished and perhaps 10% of these spread and have signifi cant consequences but, when
they do, the effects can be dramatic. Take, for example, the huge loss of native fi sh
biodiversity in Lake Victoria after the introduction of Nile perch. A more 'subtle'
example concerns the arrival in South Africa of the Var roa mite, a species that para-
sitizes the larvae of honeybees in hives and wild nests. Commercial operators can
use pesticides to keep the mite in check but 'natural' bee colonies are likely to be
wiped out. This will put plant biodiversity at risk because 50-80% of South Africa's
native fl owers are pollinated by bees (Enserink, 1999).

Fig. 1.10 Most national
parks and nature
reserves in southwest
Australia are situated in
unproductive areas (low
soil fertility) in
inaccessible terrain
(steep topography).
These areas have never
been in demand for
agriculture or urban
development. This
pattern is repeated
around the world.
(After Pressey, 1995;
Bibby, 1998.)

24
20
16
12
8
4
0

Low

Steep
Moderate

Moderate

High Flat