Conservation and Sustainable Use of the Biosphere - WBGU

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Conservation and Sustainable Use of the Biosphere - WBGU

260 G Biosphere-anthroposphere linkages: The Overexploitation Syndrome

is degraded because the structure and the function

of the ecosystem have been damaged. In the long

term even this lightly arrested overexploitation

scenario will lead to a complete conversion of the

ecosystem in question. Most boreal forests in cultivated

landscapes marked by long and intensive

human intervention have gone through that scenario.

• Type B degradation: In this scenario also the

resource is used selectively (cf Type A degradation),

but the selection criteria are not primarily

related to area but to certain species or age

groups. If the logging exceeds the reproduction

rate in the ecosystem the classic case of unsustainable

forestry will occur. The severity of damage

caused to the ecosystem then additionally

depends on the degree of function and biodiversity

loss, not just on the reproduction rate of the

renewable resource.This scenario is typical for the

majority of tropical rain forest areas that have

been more or less transformed over time into

degraded secondary forests.

• Type B conversion: In some circumstances, in the

context of natural succession, there may also be

conversion in Type B degradation. The transition

to other syndromes is significant here; it can be

triggered or promoted, for example, by the development

and opening up of an area that usually

comes hand in hand with resource use.

G 2.4

Interaction of the Overexploitation Syndrome

with other syndromes

The significance of the Overexploitation Syndrome

for the global deforestation issue varies from one forest

type to another. In the boreal forests, the Overexploitation

Syndrome describes the major component

of deforestation. Other patterns of use, such as conversion

of forest to agricultural use, play a secondary

role. In the tropical forests the direct contribution of

the Overexploitation Syndrome to deforestation is

much smaller. The conversion to agricultural land

accounts for the largest proportion of deforestation,

with about 50 per cent attributable to small-farmers

practising shifting cultivation (Herkendell and Pretzsch,

1995). This pattern was classified as an expression

of the Sahel syndrome (QUESTIONS, 1996 and

1998; WBGU, 1997; Schellnhuber et al, 1997;

Petschel-Held et al, 1999). Notwithstanding that fact,

the Overexploitation Syndrome is also of great,

albeit indirect, significance in the tropics in terms of

the global core issue of deforestation: it functions

simultaneously as a ‘pioneer’ or ‘catalyst’ syndrome

for other patterns of forest destruction.As a result of

the development of forest regions for or by timber

companies the general access to a given region is

always greatly improved. And along the newly built

roads landless shifting-cultivation farmers and large

Overexploitation Syndrome

Region 3

Development

Trigger

Sahel

Syndrome

Trigger

Region 2

Dust Bowl

Syndrome

Sahel

Syndrome

Figure G 2.4-1

The Overexploitation

Syndrome as an element

triggering the Sahel

Syndrome and the Dust

Bowl Syndrome.

Source: Cassel-Gintz et al,

1999

S.

Overexploitation

Development

Trigger

Trigger

Region 1

Dust Bowl

Syndrome

Overexploitation Syndrome

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