Pacific Islands Environment Outlook - UNEP

BIODIVERSITY 9
implementation of appropriate policies and practices for
the sustainable use, management and development of
forest and tree resources be a high priority policy issue
for PICs.
Biodiversity
Developments over the past 100 years
The Pacific region is one of the world’s centres of
biological diversity, or species richness. The western
Pacific has the highest marine diversity in the world. Up
to 3 000 species may be found on a single reef (SPREP
1993b). The region has the most extensive coral reef
system in the world. The many thousands of islands are
surrounded by a rich complex of coastal ecosystems,
including mangroves, seagrass beds and estuarine
lagoons. The evolution of island biogeography has led to
a high endemism in terrestrial species, particularly on
larger islands, which can also have a high biological
diversity. The estimated extent of biological diversity
however, is not conclusive for either marine or
terrestrial systems because detailed biological
inventories are lacking. It has been estimated that only
10 per cent of tropical species have been described
(SPREP 1992).
The early human colonization of the Pacific islands
resulted in radical changes to the biodiversity of the
region. Pressure was put on native ecosystems and
biodiversity as a result of the conversion of forests to
settlements or agricultural land, the exploitation of
forest and lagoon resources and the introduction of alien
species. There is evidence that a number of bird and
other animal species were hunted to extinction by the
early Pacific islanders (Steadman 1995). This work
shows that the early settlers to the region had a
profound effect on biodiversity even with relatively low
population densities and the lack of advanced resourceharvesting
technologies. The threats to biodiversity
have, however, become a more serious issue since
European colonization and the introduction of new and
efficient technologies and exploitative, commercial
values. In the past century, as populations have grown,
as resource extraction technologies have continued to
advance, and as commercial values have become more
widespread, the threats to native biodiversity have
increased enormously (SPREP 1993b).
Developments over the past 10 years
Between 1982 and 1991, the proportion of countries
reporting biodiversity loss as a serious problem rose
from 67 to 75 per cent (ADB 1992). The reasons for this
increase have been extensively documented in studies
prepared for the South Pacific Biodiversity Conservation
Programme (SPBCP; e.g. SPREP 1994). Despite having
the world’s highest proportion of endemic species per
unit of land area or number of human inhabitants, the
biological diversity of the Pacific islands is among the
most critically threatened in the world. A review by the
SPBCP cited birds as ‘an outstanding example of
depletion resulting from the impact of human actions on
Pacific island environments’ (Given 1992). Eight species
of native forest birds were lost in the 1980s due to
predation by the brown tree snake, accidentally
introduced to Guam from Solomon Islands. Captive
breeding programmes have prevented the extinction of
two more (Savage 1987).
World-wide, the largest number of documented
extinctions (28 between 1600 and 1899) has occurred on
the islands of Oceania, which now have more threatened
species (110) than any other region (Given 1992). Dahl
(1984) estimated that there are roughly seven times
more endangered bird species per capita in the South
Pacific than in the Caribbean, fifty times more than in
South America, and a hundred times more than in North
America or Africa.
An overall estimate of species loss in the region
cannot be provided due to inconclusive biological
inventories. However, it is clear from the information
from Solomon Islands alone that earlier estimates are
likely to be conservative. As stated earlier in this report,
there is a general paucity of data but ‘spot’
research/survey activity produces a reasonable quality of
data in a given time frame. For example, in Solomon
Islands 102 forms of birds (mostly at subspecies level)
have been considered rare (Leary 1993). Table 1.2
provides an approximate idea of the biodiversity losses in
Solomon Islands.
The PICs (especially the smaller islands) are
ecologically fragile. Effective conservation at any level is
jeopardized by the introduction of exotic plant and animal
species, unsustainable development and natural
disasters, which can make large and rapid changes to
biodiversity in islands. It is widely believed that the
uncontrolled introduction of exotic pests has been
responsible for great loss of biological diversity, although
the extent is not known.
People living in the region rely heavily on biological
resources for their economic, social and cultural wellbeing.
This includes the use of natural resources for
food, artisanal and medicinal purposes, further