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1 Introduction: The Importance of Forests
reduce the rate of surface runoff, and in the meantime increase infiltration. (Leaflitter covering the surface has a high water-retaining capacity. The infiltration of
water into forest soils is 7–8 times higher, surface runoff 2–3 times higher in forested
surfaces compared to areas not covered by forests.) The age of forests can also
impact water budget in various ways. The older the forest stand is, the more surface
runoff it is capable to retain (Illés and Konecsny 2000). In addition, forests are
habitats of a number of plant and animal species, thus unreasonable deforestation
is most dangerous to the biosphere. Apart from their genetic values, forested areas
are also valuable from the point of view of the adequate functioning of the Earth’s
system. Forest stands have an important role in the exchange of CO2 and O2 gases.
Trees incorporate a significant amount of CO2 into their bodies. (Each square metre
of the tropical rain forests absorbs about 1 kg coal from the atmosphere, i.e. 10
t/ha (Kerényi 2003).) With forests cleared, atmospheric CO2 content increases and
the greenhouse effect intensifies. Forests are also capable of binding high amounts
of dust (30–70 t/ha), thus contributing to cleaning the air from pollutants (Kerényi
Wood is one of the civilisation’s most important raw materials and energy
sources. Finally, forests play an important role in recreation as well. Their
favourable climatic impacts advance the regeneration of the human body as well
as satisfy the soul.
About 2,000–3,000 years ago, along with the development of transportation
(shipbuilding, the appearance of wheeled carts), the destruction of temperate forests
started to take place in the Mediterranean. (Many researchers associate the intensive
transgression of almost all river deltas into the Mediterranean Sea and the silting of
a number of antique harbours (Ephesos, Miletos, Ravenna, etc.) with the increased
amount of debris resulting from deforestation.) Widespread grazing also impeded
the regeneration of forests. Roughly 200 years ago, the majority of the forests in
most of Europe and in Southeast Asia underwent the same process, partly due to the
population growth and the demands by the developing industry. The natural forest
cover fell victim to European settlers gaining ground in North America ca. 100 years
ago (Plate 8.1). By the 20th century, deforestation became focused on the tropics.
Today the destruction of the tropical rain forests takes place at an intensity never
witnessed before, for which the primary explanation is given by the economic and
social backwardness and the financial exposedness of the tropical countries.
Ten thousand years ago, an area of approximately 62.2 million square kilometres was covered by natural forests. (According to the definition by FAO, forests
are areas at least 0.5 ha in size and in which at least 10% of the area is covered by
foliage.) The area of natural forests, which represented nearly 42% of the land surface, dropped to 38.7 million square kilometres (26%) (Rakonczai 2003; Fig. 8.1).
Each year, ca. 3 billion tonnes of wood is used. More wood is used in Europe for furniture, construction material, firewood and paper than metals for any other purposes.
The rate of deforestation at the beginning of the 21st century is estimated to be
16 million hectares per year. Of this, about 14 million hectares are cleared in the
tropics. As a result of afforestation, the net loss of forested areas is ‘only’ ca. 10
Plate 8.1 A typical deforested landscape in the Midlands of England (Karancsi 1998)
The uppermost map in Fig. 8.1 indicates former natural forested areas, the middle one the total area of present-day natural and planted forests whereas the lower
one indicates the extension of natural forests now. Monoculture, i.e. when only a
single tree species is planted over large areas, is a feature of artificially planted ‘cultivated forests’. With the trees of such forests becoming exploitable at the same time,
clear-cutting, entailing intensified erosion processes (Plate 8.2) and land degradation
(Plate 8.3) seem to be nearly unavoidable. In times of forest renewals, for economic
reasons, alien species are often planted replacing indigenous ones with mostly negative impacts on the whole ecosystem (soil acidification, severe species degradation,
Hereafter, an overview will be provided on the relevance of tropical rainforests
and on the consequences of clear-cutting on their environment (Fig. 8.2).
These forests with complicated vertical structures are extremely abundant in
species. In certain regions of Amazonia, a single hectare contains as many plant
and animal species as the total of European forests. (Here, as many as 2,000 tree
species can be present on 1 ha in contrast to the forests of the moderate climate
where only a maximum of 20 tree species can be found.) This is the richest ecosystem of our planet. At its greatest extension, it is found in the Amazon and Congo
basins and also in Southeast Asia and Central America.
Tropical rainforests are also cleared to provide area for crop cultivation and
animal husbandry as well as for the trading of tropical wood.
During forest clearance, first the multi-storied abundant foliage, responsible for
the transpiration of large amounts of water, is removed. As the transpiration surface is reduced, the moisture content of the air drops and this results in lesser and
more sporadic rainfall. The existence of a tropical forest is based on rainfall. With
decreasing amounts of rainfall, the vegetation also begins to grow less dense and
Fig. 8.1 Forested areas in the past and at present (Bryant et al.1997)
degraded. With a sparse foliage, irradiation increases and, due to the more intensive
vertical turbulent air movement, violent hailstorms become common.
The water-retaining capacity of the vegetation cover reduced by the clearance of
rainforests will have serious consequences. The foliage, coats of moss and lichen as
well as epiphyte plants of the rainforests intercept rainwater conveying it towards
the soil slowly (by drops). On the contrary, rainwater in deforested areas reaches
the ground surface unhindered, washing away soil particles (erosion). The otherwise thin soil of the rainforests is gullied by erosion into badlands. In deforested
areas, the increasingly scarce vegetation will be composed of less demanding plant
species. Violent hails, after a while, can entirely wash away the laterite soils from
the bedrock and make revegetation impossible.
Plate 8.2 Gully development after clear-cutting at the western rim of the Medves Plateau
Plate 8.3 Typical ‘badland’ formation after deforestation at Kazár, North-Hungary (Karancsi
Intense rainfall will raise the water-level of rivers causing floods, which destroy
agricultural lands and settlements along the river banks. Fluvial sediments will fill
up lakes furthering large-scale eutrophication.
Tropical rainforests evenly use solar energy and reflect only 8–14%. The albedo
of the bushland formed after forest clearance is 15–20%, whereas that of an eroded
surface can exceed 30%. Intensive inward and outward radiation also mean a great
Fig. 8.2 The impact of
tropical forest clearance on
the environment (Balázs
fluctuation of temperature that is not tolerated by plants accustomed to evenly warm
and humid climate. Further species will be extinct.
The clearance of tropical rainforests also has an influence over further regions,
where the amount of precipitation is also reduced and seasonal droughts become
more frequent there. Thus former deciduous closed forests are replaced by savannas
with groves, wooded savannas become treeless grasslands, whereas in former grasslands, grass becomes sparse and desertification begins to take place. This process
has a disastrous impact on farming. Farmers are forced to move closer to areas under
equatorial climate and with a higher amount of precipitation, where, on the contrary,
endowments for production (shallow soils poor in nutrients) are less favourable and
new agricultural areas are gained by forest clearance. Stock keepers are also forced
to leave their pastures abandoned under desertification and have to form new grazing
lands for either farmers or forested areas.
Tropical rainforest clearance is also associated with the destruction of local
8.2 History of Woodlands in the Carpathian Basin
The Holocene was the period when the Carpathian Basin became forested and the
stock-breeders and farmers appeared. This is, therefore, also the advent of deforestation. The parallel processes of the natural expansion of forests and anthropogenic
impacts influenced the history of Hungary’s forests in the past ca. 8,000 years.
(Traces of the first settlements of farmers in Hungary are from the 6th millennium
BC. The age of the earliest Neolithic site (Szeged-Gyálarét) is dated by the radiocarbon method at 7090 ± 100 BP (Bácskai 1982)). It is estimated that without human
influence on the environment, the natural vegetation of Hungary at present would
be forest steppe and more than 60% forested (Medzihradszky 1996).
Forested areas reached their greatest extension during the Paleolithic and the Iron
Age, as climate provided the most favourable conditions to the expansion of woods
while nature transformation by humankind were only of a minor scale at that time.
During the Neolithic Period with more arid climate, there was a decrease in wooded
areas, while grasslands expanded. Prior to the beginning of human landscape transformation, approximately 60% of Hungary was covered by forests. By the time of
the Magyar Conquest, forest clearance reduced the cover to 43%. The country witnessed the lowest rate of forested areas (11.8%) in 1913 (the data is for the area of
present-day Hungary). Today, forests cover more than 20% of the area; however,
only one-third of this resembles former (potentially) natural forests whereas the rest
is plantation or intensively transformed forests (Németh 1998). [Here, the notion
of (potential) natural forest refers to the presence of zonal associations (Turkey
oak-sessile oak, hornbeam-oak on higher terrains, and beech on cooler slopes with
northern exposure) less disturbed by humans.]
According to the results of pollen analyses, the Hungarian low mountains could
have been mostly covered by beech woods in the Subboreal (2,500–5,000 years
ago) (Pócs 1981). In the Subatlantic, lasting to the present, such beech woods
retreated to higher regions. Human appearance in the Carpathian Basin is estimated
at about 6000 BC. Anthropogenic impacts were, in the Neolithic, restricted to rather
small patches, landscape transformation only accelerated later. Farming and animal
husbandry have been gaining ground at the expense of forests along the lowland
margins from the Copper Age. Forest clearance involved accelerated soil erosion
and renewed movements of wind-blown sand.
8.3 Case Study: Geomorphological Impacts of Deforestation
Through the Example of the Medves Region
The research area of 32 km2 , henceforth called the Medves Region, is part of one
of the micro-region of the North Hungarian Mountains, called the Medves Plateau,
Central Europe’s largest basalt plateau (with an area of 13 km2 , of which an 8 km2
section falls within the territory of Hungary) and the adjacent regions with a more
varied morphology and basalt peaks of higher elevations (e.g. Salgó – 625 m,
Fig. 8.3 The Medves Region with the study area (Karancsi 2005)
Szilvásk˝o – 628 m) (Horváth et al. 1997; Karancsi 1998a,b). This area with diversified morphology neighbouring Slovakia has been part of the Karancs–Medves
Landscape Protection area since 1989 (Fig. 8.3).
8.3.1 A Historical Review of Agricultural Landscape Alterations
To understand anthropogenic impacts, the temporal and spatial variations and
human activities in the region have to be studied. In lack of a comprehensive
archaeological survey, general data as well as written and mapped sources found
in archives provide information on the area (Erd˝osi 1978; Gazdag 1964).
The majority of the research area has been used by agriculture and forestry
for a long time (Dornyay 1928). In the Copper Age, beginning here around 2500
BC, an ethnic group similar to the Badenian Culture populated the area. Unlike
Stone Age people, they were primarily stock keepers, thus were often forced to
change their locations. During herding, new pastures were created by, in addition
to migration, forest clearance, i.e. the appearance of anthropogenic impacts can be
estimated by and large to this period in the region. Migratory herding caused trampling; deforestation accelerated erosion, in other words, gradual land degradation
The Bronze Age (1800–750 BC) witnessed population growth. Among the
people of the Iron Age starting around 750 BC, Scythians involved in animal husbandry (mainly of horses dominated the area for nearly 300 years).