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