Conservation and Sustainable Use of the Biosphere - WBGU

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Conservation and Sustainable Use of the Biosphere - WBGU

90 E Diversity of landscapes and ecosystems

Box E 1.1-1

Organisms

Organisms are characterized by four properties. They

have a specific structure, ie they have outer limits that

clearly separate them from the outside world.They have

a metabolism that provides energy and nutrients to

maintain the functions of life. They can reproduce, ie

they are capable of ensuring, by division or by creating

offspring, that ageing or dying organisms are replaced by

younger, fitter ones. Furthermore, thanks to the ability

to mutate (changes in genetic information) organisms

are capable of adapting to changing environmental conditions

(Section D 2). Moreover, higher organisms are

capable of learning. By means of individual information

stored in neurones they have another very effective

adaptation mechanism.

In order to maintain their structures and life processes,

organisms have to be fed usable energy in the

form of radiation or chemically bound energy as well as

nutrients. Excreted products from organisms, which are

released into the environment as heat and wastes, cannot

be further used by the same species. Organisms are

thus ‘flow through systems’ whose existence is only

ensured by the continued supply of usable energy and

substances from outside sources.

These ecosystems are subject to major internal

modification by varying geological, pedological and

orographical site factors as well as human intervention.

The degree of aggregation to be used in each

case is determined by the question being addressed.

Questions concerning global biogeochemical cycles,

for example, are dealt with at the biome level,

whereas studies on the ß-diversity of plants (change

in the number of species in a habitat) are carried out

at an ecotope level. In Germany, for example, 509

biotope types have been identified for questions of

biotope conservation and land use planning (UBA,

1997a), whereas the above-mentioned global breakdown

according to Prentice and Kaplan names only a

few biomes for Germany.

The consideration of landscapes as geographical

or functional units can be done at different hierarchical

levels.The following is a brief description of landscape-forming

elements in their hierarchical organizational

form.

E 1.2

From natural to cultivated landscapes

Over millennia, humankind has increasingly intervened

in natural landscape diversity and, in the

process, has changed its habitat by chance or consciously

redesigned it. In the last few decades,

humankind has developed into an environmental

factor that accelerates the exchange of matter

between ecotopes, landscapes, biomes and continents

in previously unknown ways. As a result, there are

major changes in biological diversity at the species,

population and ecosystem level that are hard to

quantify and whose consequences cannot be reliably

predicted (WBGU, 1998a).

Viewed ecologically, humans are extremely competitive,

heterotrophic consumers. With the help of

their intellectual abilities, they have considerably

developed their biological characteristics and have

enriched them culturally. As a being endowed with

reason, it is possible for them to foresee events and to

design their environment.With these human abilities

that have developed over biological evolution, ‘culture’

has appeared as a new factor in the biosphere.

Since then, cultural evolution has accompanied biological

evolution and overshadowed it at times, but it

has never cancelled it out or replaced it. Cultural evolution

can be explained in terms of humans’ need to

free themselves from the constraints placed on them

by nature. If we look at the development of cultural

evolution, we can make a rough categorization into

five stages that can be identified to varying extents

and at different times in all human habitats:

1. Hunter-gatherer stage,

2. Stage of agricultural and forestry land use,

3. Stage of urban cultures,

4. Industrial and high-energy use stage,

5. Information and communications stage.

These five stages came about at different times and

characterize the periods named after them, but they

have not completely replaced each other. Rather,

they can be found next to each other or linked

together to differing extents, and they all have a combined

effect on the biological diversity of ecosystems.

People still hunt and gather today, albeit with different

equipment and techniques. Similarly, agriculture

and forestry are practised alongside industrial technologies

and information technology. Humankind’s

natural environment was largely changed into a cultivated

landscape in the course of this development.

In this process, self-organization, reproduction and

evolution were replaced to a varying degree by the

targeted regulation and control by mankind. The

existing structures and internal cycles were frequently

destroyed and decoupled during this process.

Ecosystems shaped by humankind are therefore

often similar to the flow-through systems that are

characteristic for organisms. Humankind did not find

it satisfactory to confine the adaptation of its needs

and wishes to the natural productivity and utility of

its habitat. In order to elude the constraints posed by

nature, people developed collection, concentration,

reinforcement and distribution processes and created

the systems associated with these actions. The

perfection of hunting and catching methods, the

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