Conservation and Sustainable Use of the Biosphere - WBGU

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Conservation and Sustainable Use of the Biosphere - WBGU

100 E Diversity of landscapes and ecosystems

nutrient depletion and acidification with simultaneous

N eutrophication. Both processes work against

biodiversity because they remove locational differences

in the landscape or differences generated by

man.Thus, today around two-thirds of forest soils can

be classed as highly acidified (BMELF, 1997) and

receive excessive nitrogen deposits at the same time.

This digression about the development of ecosystems

in Central Europe makes it clear that this ecologically

‘favourable area’, which developed in areas

with young, little-weathered substrates and a temperate

climate, has undergone an extremely dynamic

development over the last 11,000 years. Natural

changes in the climate and the soils meant that living

communities had to constantly adapt. However,

human interventions were especially serious; over

millennia humans had deliberately shaped the landscape

and, in the process, created a cultivated landscape.

In the species-poor region of Central Europe,

‘disruptions’ caused by humans initially led to an

increase in biodiversity, which reached its peak

around 100–200 years ago. Today there are 509

biotope types in Germany. Of these, 69 per cent are

at risk, whether by the reshaping of landscapes during

economic intensification or by the abandonment

of conventional use forms (UBA, 1997a). In addition,

completely new ecosystems have developed that are

still evolving. In this environment, the challenge of

biotope and species conservation can only be met by

allowing conservation and use to co-exist (Section

E 3.9). Protecting processes alone would change this

landscape into one consisting almost entirely of

woodland, with a corresponding loss of diversity.

However, if we want to conserve the cultivated landscape

of the past, we will also have to conserve the

associated use. All other solutions lead to biological

changes whose results cannot always be precisely

predicted, but that need to be assessed if the cultivated

landscape is to be developed sustainably and in

a way that is environmentally sound.

E 2.2

Amazonia: Revolution in a fragile ecosystem

Fine smoke is wafting through the rainforest, blurring

outlines under a blue-grey veil and making the

sun appear as a milky disc. It started a few weeks ago,

intensified, diminished and intensified again, but the

smoke, that makes your eyes water and affects your

breathing was always there. The fire, with which the

small-scale farmers wanted to clear their plots of

weeds, wood, scrub and pests as usual, has got out of

hand this year. An unusual drought has kept the rain

away that would otherwise keep the fires under control

and, therefore, large areas of the forest have been

burning in many places and for many weeks now. But

who is bothered about these fires in the parts of

Amazonia far from the major cities? Although the

Governor has declared a state of emergency, there is

no money for the deployment of fire-fighting helicopters

and planes. Because no cities, no international

transport routes or even centres of tourism are

affected by the smoke, the central government is not

very interested in the fires and the international public

takes no notice whatsoever of the catastrophe.

Every year 300–500 million ha forest burn down

around the world, and it is only reported by the

media reports it in exceptional cases. Forest fires are

natural and have always destroyed large areas of

woodland at certain intervals. Exceptional climatic

conditions greatly heighten the risk of forest fires;

just lightning striking a dry tree can be enough to

trigger an extensive fire. However, forests can regenerate

and revert to the original situation from before

the fire, but this can take decades to centuries.

People, too, have over the millennia used fire to

clear their settlements of vegetation or to clear the

forest in order to grow crops. However, this burning

down also brought other advantages; the ash fertilizes

the soil and neutralizes the acid stored in it,

greatly improving the growth of crops.The Indians in

the Amazon basin also know this, and they have been

using this technique, shifting cultivation, since they

migrated to this area about 8,000 years ago. However,

they also know when they can burn so that the

fires do not get out of control. They also chose such

small areas that the interventions would not lead to

long-term changes in the overall ecosystem. Because

the soil’s nutrient reserves are exhausted after

around three years, it is no longer worthwhile to grow

crops on it. The forest regrows over the cleared area

and the settlers migrate to another place, to return

30–100 years later. However, this rhythm has

changed. Slowly at first when the first conquerors

and colonists appeared at the start of the Modern

Era, but then with increasing speed. Today concessionaires,

big land owners, gold-diggers and small

farmers intervene in the forests, largely without control.

The changes induced by the use of the forests,

right up to the conversion of the forest into grassland

or arable and plantation land, exceed the forests’

regeneration capabilities, with the consequence that

large areas of primary forest are disappearing.

E 2.2.1

Geological and climatic features of the Amazon

basin

What makes the interventions in the tropical rainforests

different from interventions in the temperate

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