Conservation and Sustainable Use of the Biosphere - WBGU

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Conservation and Sustainable Use of the Biosphere - WBGU

150 E Diversity of landscapes and ecosystems

Box E 3.3-6

Forests and biological diversity

The loss of forest biodiversity results both from the loss of

forest land (Section E 3.3.4.4) and from the degradation of

existing forests. Both processes continue apace and, after

centuries of forest destruction in temperate and boreal

areas, since the mid-twentieth century they have taken

place particularly actively in the tropics. With regard to the

loss of biological diversity, special importance is attached to

the loss of tropical forests and forest degradation because

the tropical forests are disproportionately richer in species

than temperate and boreal forests and the agro-ecosystems

that result from the conversion are much more fragile.

The best contribution to the conservation of forest biological

diversity can be made by the biodiversity of forests

being understood as a carrier of biological resources. The

value of these biological resources comes to bear at various

levels, ranging from the household level (firewood, food,

medicine), local (food, firewood, medicine, building materials),

national (wood products, water, firewood, etc) and

international markets (wood products, resins, oils, tourism,

etc) (Section H 5). Forest biodiversity gains global significance

as an important carrier of information for future

options on technological or medical developments (Section

D 3.3). Further importance may be attached to the biodiversity

of forests regarding their stabilising effect on the

global climate (Section F 2). The importance of forests as

biological carbon sinks is currently the subject of international

discussion (WBGU, 1998b).

The information on the number of species in forests is

highly unreliable and fluctuates between 2 and 80 million

species. The mean value of the estimates is around 10 million

species, and it is assumed that the vast majority of these

are arthropods (WCMC, 1992; Heywood and Watson, 1995).

In turn, around 50–90 per cent of arthropods are to be found

in the tropical forests and this emphasizes their high fauna

diversity. With respect to plant biodiversity the much

quoted example form Borneo can be used, where 700 tree

species have been identified on 10 ha of forestland, in other

words more species than occur in the whole of North America

(Rodgers, 1996).

In light of the pressure on land use described above, further

losses of forests in the tropics will be inevitable (Chapter

G). The majority of the conversion will continue to be

for agricultural use. It is therefore all the more important to

integrate the land use changes into comprehensive concepts

that are anchored at regional level (Section E 3.9). The

maintenance of the agricultural productivity of the converted

forestland or increasing the productivity on existing

agricultural land must be an important objective (Section

E 3.3.4.2).

Although most national policies emphasize that the

remaining forestland should be protected, deforestation

continues on a global level. From this, it can be seen that the

causes of forest destruction are multi-faceted and differ

from region to region. Not only direct reasons, such as the

spread of slash and burn, but also indirect reasons due to the

failure of policies, such as rural poverty, lead to the continuing

destruction of forests (NNA, 1998; Jepma 1995; Pearce

and Moran, 1998; Chapter G).

Since the existing biological diversity of the forests cannot

be preserved as a whole and species are becoming

extinct more quickly than all the existing species can be

recorded (Pimm et al, 1995; Section D 1), special significance

is attached to the functional evaluation of biodiversity

alongside recording habitats. Two questions can be

asked:

• How much biodiversity is needed to conserve multifunctional

forests (Section E 3.3.9)?

• Can this question be answered on time?

The first steps along this route have been made with the

identification of hotspots of biodiversity, the designation of

indicator taxa and the mapping of the usage pressure on

existing forest ecosystems (Global Forest Watch; WRI,

1999).An accompanying measure that could help to reduce

the predatory exploitation of forest resources is the certification

of wood products and forms of management (Box

E 3.3). A legally binding regulation for forest protection is

long overdue (Section I 3.4.4). The instruments and means

of implementation currently available are, however, so limited

that it is extremely doubtful whether the dynamics of

the current trend can be decisively influenced.

be minimized, far-reaching changes in eating habits

and in the way we keep and use animals will have to

be effected.

• Overnutrition with foods of animal origin must be

reduced because it is inefficient on the one hand

and has a negative impact on health on the other.

• The productivity of domesticated animals should

be optimized because large unproductive stocks

have a disproportionate negative impact on biodiversity.

This should also include ‘improvement’ of

traditional livestock breeds.

• Grazing practices should be more oriented

towards the carrying capacity of the grasslands in

order to prevent the degradation of the grazing

areas.

Switching to animal foodstuffs from the sea is also

limited because some natural fish populations are

already being overexploited. Although aquaculture

is a possible alternative, high-quality feed must be

used, which – in turn – mostly comes from terrestrial

ecosystems. Also, establishing cultures of this kind in

lakes and shallow seas is problematic from the point

of view of environmental pollution and the impact on

the biodiversity of aquatic ecosystems (Section

E 3.4).

The production of food using biotechnological

methods has not yet progressed to a level where it

can relieve shortages. Although there is great potential

for the biological conversion of plant wastes or

residues into feedstuffs and foods, only a few

approaches have so far proved to be economically

sustainable. New information and conversion methods

should be developed for the better use of plant

biomass (such as wood or straw) as feed and food. In

this respect, molecular biological methods could

open up new opportunities.

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