94 Ecology and Applied Environmental Science
regeneration is not hampered by grazing, a second fire or other human
interventions, it can ensure the restoration of the forest vegetation to a
large degree. The need for artificial reforestation arises only in cases where
natural regeneration does not succeed, for various reasons. Therefore artificial reforestation, which is a difficult and extremely costly activity, plays
a rather limited role in forest restoration after fires.
In Greece, the phenomenon of forest fires has exhibited a significant
increase during the last 40 years and constitutes the major deforestation factor. A great percentage of the disasters (30–40% of the number
of fires and 60–70% of the burned areas’ surface) is due to arson, which
proves that the effort for land use change towards the direction of pastures
and building plots is the most important factor for fires. Of course, we
should not ignore the periodic draughts and the potential climate change
that create favourable conditions for a greater number of fires and more
destructive ones.
5.2.7 Soil and agricultural activity
5.2.7.1 Erosion and Desertification
By the Neolithic era, deserts had already expanded significantly due to
human action. Deforestation, over-grazing and cultivation of friable soil are
basic factors. It is possible that in certain eras some small climatic changes
assisted this process and accelerated deforestation. However, the prevailing
views suggest that human activity was much more decisive than the influence of the climate. The Nile valley case is characteristic. For thousands of
years, it had the ability to feed Egypt’s inhabitants, because the ecosystem’s
functions, with the periodic risings of the river’s level and the transport
of nutrients, had remained undisturbed. This was so because the sources
of the Nile were mostly in inaccessible areas that had not received strong
human interventions until recently. On the contrary, in the case of Tigris
and Euphrates Rivers, degradation is great. Their sources are in the
Armenian plateaus, which have suffered the impacts of human activities
and especially those of extensive livestock farming for long periods. The
gradual destruction of natural vegetation by over-grazing, timber felling
and thoughtless cultivation caused extensive erosion. The river waters are
overloaded with debris that deluge the valleys and create extensive alluviums at the river mouths. The old empires that developed in the fertile land
of Mesopotamia managed to decelerate the degradation for hundreds of
years by land reformation works. However, when the invaders shattered
the strong and organized states, the irrigation system was destroyed and
the area entered a gradual desertification process.
In vulnerable watersheds where the conditions are favourable, traditional agricultural intervention can destroy a region’s productivity through
regeneration is not hampered by grazing, a second fire or other human
interventions, it can ensure the restoration of the forest vegetation to a
large degree. The need for artificial reforestation arises only in cases where
natural regeneration does not succeed, for various reasons. Therefore artificial reforestation, which is a difficult and extremely costly activity, plays
a rather limited role in forest restoration after fires.
In Greece, the phenomenon of forest fires has exhibited a significant
increase during the last 40 years and constitutes the major deforestation factor. A great percentage of the disasters (30–40% of the number
of fires and 60–70% of the burned areas’ surface) is due to arson, which
proves that the effort for land use change towards the direction of pastures
and building plots is the most important factor for fires. Of course, we
should not ignore the periodic draughts and the potential climate change
that create favourable conditions for a greater number of fires and more
destructive ones.
5.2.7 Soil and agricultural activity
5.2.7.1 Erosion and Desertification
By the Neolithic era, deserts had already expanded significantly due to
human action. Deforestation, over-grazing and cultivation of friable soil are
basic factors. It is possible that in certain eras some small climatic changes
assisted this process and accelerated deforestation. However, the prevailing
views suggest that human activity was much more decisive than the influence of the climate. The Nile valley case is characteristic. For thousands of
years, it had the ability to feed Egypt’s inhabitants, because the ecosystem’s
functions, with the periodic risings of the river’s level and the transport
of nutrients, had remained undisturbed. This was so because the sources
of the Nile were mostly in inaccessible areas that had not received strong
human interventions until recently. On the contrary, in the case of Tigris
and Euphrates Rivers, degradation is great. Their sources are in the
Armenian plateaus, which have suffered the impacts of human activities
and especially those of extensive livestock farming for long periods. The
gradual destruction of natural vegetation by over-grazing, timber felling
and thoughtless cultivation caused extensive erosion. The river waters are
overloaded with debris that deluge the valleys and create extensive alluviums at the river mouths. The old empires that developed in the fertile land
of Mesopotamia managed to decelerate the degradation for hundreds of
years by land reformation works. However, when the invaders shattered
the strong and organized states, the irrigation system was destroyed and
the area entered a gradual desertification process.
In vulnerable watersheds where the conditions are favourable, traditional agricultural intervention can destroy a region’s productivity through