Introduction – humans, nature and human nature - Ecological Applications: Toward a Sustainable World - page 12

Fig. 1.9 Principal
'drivers' of biodiversity
change in various
terrestrial and aquatic
ecosystems. The cell
shade expresses expert
panel opinion on the
impact of each driver
on biodiversity over the
last century. The arrows
indicate the predicted
future trend in each
driver's impact. (From
Millennium Ecosystem
Assessment, 2005b.)

Pollution
(nitrogen,
phosphorus)

Habitat
change

Climate
change

Invasive
species

Over-
exploitation

Boreal

Forest Temperate

Tropical

Temperate grassland

Mediterranean

Dryland

Tropical grassland
and savanna

Desert

Inland water

Coastal

Marine

Island

Mountain

Polar

Driver's impact on biodiversity
over the last century

Driver's current trends

Decreasing impact
Continuing impact
Increasing impact
Very rapid increase
of the impact

Low

Moderate
High

Very high Source: Millennium Ecosystem Assessment

pose a particular risk in forest and dryland habitats (other than desert) and in inland
and coastal waters, whereas overexploitation may not fi gure quite so dramatically
in future (except in aquatic environments, polar regions and tropical forests). These
scenarios must underpin the plans and priorities of ecosystem managers around
the globe.

1.2.4 Habitat loss -
driven from house
and home

Trends in extinction threat refl ect, in large measure, the continuing escalation of
the most powerful of human infl uences - the loss of between 0.5 and 1.5% of wild
habitat each year (Balmford et al., 2003). To date, approximately one quarter of the
earth's surface has been transformed for agriculture. And in total, well over half of
temperate broadleaf and Mediterranean forests have been lost together with 40-50%
of tropical and subtropical forests and grasslands (Millennium Ecosystem Assess-
ment, 2005b). Moreover, since 1980 about 35% of mangroves and 20% of tropical
coral reefs have gone. In addition to the actual loss of habitat, what remains is almost
invariably highly fragmented in its distribution and supports fewer species as a
result. Because they are less hospitable to humans, the world's deserts, mountains,
boreal forests and tundra have fared less badly.