Conservation and Sustainable Use of the Biosphere - WBGU

Sustainable land use E 3.3
149
Table E 3.3-5
Regional change in forest
cover.
Source: Abramowitz, 1998
Region Original Remaining Annual Proportion of
forests forests net change primary forest
[10 3 km 2 ] [10 3 km 2 ] (1990–1995) [%]
[% year -1 ]
Africa 6,799 2,302 -0.7 23
Asia 15,132 4,275 -0.7 20
North America 10,877 8,483 0.2 44
Central America 1,779 970 -1.2 18
South America 9,736 6,800 -0.5 65
Europe 4,690 1,521 0.3 1
Russia 11,759 8,083 0.1 43
Oceania 1,431 929 -0.1 34
World 62,203 33,363 -0.3 40
Today the mean annual change in the forest
acreage in the species-rich tropical forests is especially
large. It is extreme in Brazil and Indonesia.
Both countries together have annual forest losses of
over 3.6 million ha, that is a third of the forest acreage
of Germany for each country. With deforestation
rates of over 0.4 million ha each, the losses in countries
such as Zaire, Mexico, Bolivia, Venezuela and
Malaysia are also considerable. In Russia, which does
not provide any official figures, experts estimate that
approx 4 million ha of taiga are cleared per year.
These figures do not include the insidious changes
resulting, for example, from small, repeated fires that
escape detection by satellites over a long period
(Cochrane and Schulze, 1999).
The relationship of forest acreage to population
figures is influenced both by the development of
deforestation and by population growth. In 1950
around 2.55 thousand million people lived on the
Earth; the figure had more than doubled to 5.7 thousand
million by 1995. In 1950 there was an average of
1.6 ha forest available per inhabitant of the world;
this figure had fallen to 0.6 ha by 1995. The forecasts
predict another halving to 0.3 ha per inhabitant for
2025. However, it is not only the conversion of the
forests that is changing biodiversity (Box E 3.3-6),
but also the increasing conversion of primary forests
into secondary forests or plantations. Here, the
uncontrolled exploitation of primary forests, in particular,
has a negative impact.
The further destruction of the forests can only be
stopped by:
– ceasing uncontrolled conversion of the forests into
arable and grazing land and into areas for transport
infrastructure and settlement;
– regulating forest use, in a manner incorporating
existing knowledge and geared to sustaining timber
increment (sustainability principle);
– establishing segments of regulated, highly productive
plantations in order to produce the required
quantities of certain wood qualities while protecting
natural forests;
– halting the use-related degradation of the biotic
and abiotic components of forest ecosystems;
– reducing the deposition-related stresses upon
forests from acids, nitrogen and contaminants.
E 3.3.4.5
Substitution of land-use products
Nutritional statistics show that in North America
today the food supply per head of population is
15,181 kJ per day, 34 per cent of which comes from
animal production. The figures for western Europe
are 14,424 kJ, 33 per cent of animal origin. In the
developing countries of Latin America 11,438 kJ are
available to every inhabitant per day, 17 per cent of
animal origin. In the Far East the figures are 9,285 kJ,
7 per cent from animal production, and in the developing
countries of Africa 8,872 kJ, only 5 per cent of
which is of animal origin.
The oversupply of food in the industrialized countries,
coupled with a surplus of animal protein, holds
the potential to relieve shortages in the global food
supply. However, because of the relatively small proportion
of the world’s population that is oversupplied
in this way, the relief that can be achieved by
reducing the proportion of animal foods should not
be overestimated, especially when we remember that
the world’s population is growing by over 80 million
per year. Substitution is also limited because only
feedstuffs that are also suitable for human consumption
can be considered. Moreover, it must also be
considered that ruminants sometimes graze grasslands
which cannot be used for any other purpose.
Animal production and its rapid growth in recent
years (Table E 3.3-6) exerts an enormous influence
on the biodiversity of our world.This influence is not
only due to the fact that 22 million km 2 are used as
grazing land, but also that animal feed is produced on
21 per cent of arable land. If, on the one hand, the
demand for food from animal sources is to be met
and, on the other hand, ecological side effects are to