Values, Alterations and Degradation of the Natural Landscape 107
• Water, air, soil etc. pollution and toxic pollution of the trophic chains
• The climatic change prospect
5.5.1 Flora and Fauna
The total of plant species of a terrestrial or aquatic ecosystem is called flora.
The term vegetation refers to the total of plants that cover the surface of
an area. The vegetation of forests, meadows and marshes are characteristic
cases. The processes, causes and outcomes of natural vegetation degradation are characteristically described in the case of forests.
The degradation of vegetation, and especially forest clearing, entails,
among other factors, the decrease of flora variety. During the past centuries,
but especially since 1800, a great number of plant species have disappeared
from the biosphere as a consequence of man’s actions. The destruction of
tropical forests and of other significant biotopes, over-grazing, over-collection
of medicinal and aromatic plants and the introduction of alien species into
sensitive ecosystems are the major causes for the extinction of plant species.
The total of animal species of a terrestrial or aquatic ecosystem is called
fauna. A range of factors has led man—since the Palaeolithic era up until
the 20th century—to cause the gradual decrease of the populations and
the extinction of more and more species of wild fauna. Vegetation offers
food and shelter to most of the terrestrial animal species; thus, the destruction of vegetation or, more generally, of the biotopes, constitutes, as a rule,
the most significant degradation factor of the fauna. Actually, extensive
deforestation, which continues today in the tropical regions, has caused
the extinction of many mammals, birds etc. in Europe, North and South
America, Australia, Polynesia and other regions. Great disasters have also
been caused by the drainage of wetlands, and generally the changes of land
use in favour of agriculture, livestock farming and residential development.
Over-hunting and over-fishing are significant factors for fauna degradation, which has driven many species of big mammals, birds and marine
organisms to extinction. The change of competition conditions, with the
introduction by man of alien species, that is, which are coming from other
parts of the planet, into virgin ecosystems, also has had adverse consequences. For many sea mammals, big terrestrial mammals and fish, the
decrease began long before the industrial era. Man’s expansion 40,000 years
ago, during the Pleistocene period, caused the extinction of a significant
number of animal species because of over-hunting and deforestation. It has
been ascertained that the extinction of animals closely followed man’s
progressive colonization of various continents and islands. It is estimated
that mass species extinctions took place about 40,000 years ago in Africa
and Southeast Asia, 20,000–13,000 years ago in Europe, 13,000–2000
years ago in North and South America, 800 years ago in Madagascar
and 700 years ago in New Zealand. The extinction rates were accelerated
• Water, air, soil etc. pollution and toxic pollution of the trophic chains
• The climatic change prospect
5.5.1 Flora and Fauna
The total of plant species of a terrestrial or aquatic ecosystem is called flora.
The term vegetation refers to the total of plants that cover the surface of
an area. The vegetation of forests, meadows and marshes are characteristic
cases. The processes, causes and outcomes of natural vegetation degradation are characteristically described in the case of forests.
The degradation of vegetation, and especially forest clearing, entails,
among other factors, the decrease of flora variety. During the past centuries,
but especially since 1800, a great number of plant species have disappeared
from the biosphere as a consequence of man’s actions. The destruction of
tropical forests and of other significant biotopes, over-grazing, over-collection
of medicinal and aromatic plants and the introduction of alien species into
sensitive ecosystems are the major causes for the extinction of plant species.
The total of animal species of a terrestrial or aquatic ecosystem is called
fauna. A range of factors has led man—since the Palaeolithic era up until
the 20th century—to cause the gradual decrease of the populations and
the extinction of more and more species of wild fauna. Vegetation offers
food and shelter to most of the terrestrial animal species; thus, the destruction of vegetation or, more generally, of the biotopes, constitutes, as a rule,
the most significant degradation factor of the fauna. Actually, extensive
deforestation, which continues today in the tropical regions, has caused
the extinction of many mammals, birds etc. in Europe, North and South
America, Australia, Polynesia and other regions. Great disasters have also
been caused by the drainage of wetlands, and generally the changes of land
use in favour of agriculture, livestock farming and residential development.
Over-hunting and over-fishing are significant factors for fauna degradation, which has driven many species of big mammals, birds and marine
organisms to extinction. The change of competition conditions, with the
introduction by man of alien species, that is, which are coming from other
parts of the planet, into virgin ecosystems, also has had adverse consequences. For many sea mammals, big terrestrial mammals and fish, the
decrease began long before the industrial era. Man’s expansion 40,000 years
ago, during the Pleistocene period, caused the extinction of a significant
number of animal species because of over-hunting and deforestation. It has
been ascertained that the extinction of animals closely followed man’s
progressive colonization of various continents and islands. It is estimated
that mass species extinctions took place about 40,000 years ago in Africa
and Southeast Asia, 20,000–13,000 years ago in Europe, 13,000–2000
years ago in North and South America, 800 years ago in Madagascar
and 700 years ago in New Zealand. The extinction rates were accelerated