Environmental Engineering Reference
In-Depth Information
The natural situation lasted in Europe until the first
centuries
AD
and in North America until the arrival of
European settlers.
to landscape changes in rural areas at an ever-
increasing speed and scale. Chemistry enabled the
development of artificial fertilizer, and engineering
sciences made large-scale mechanization possible.
In Europe this process became especially apparent
after the Second World War when politicians feared
famine and stimulated large-scale reallotment pro-
grammes and further rationalization of agriculture. The
process was further accelerated with the formulation
of the Common Agricultural Policy in the European
Community during the 1960s. This policy has been so
successful that Europe has become a major exporter
of food.
3.5.2 Human-affected landscapes
Central and western Europe
Human impact on landscapes in north-west Europe
dates back to the Neolithic era (7000 -5000 yr before
present) but at first this influence was only locally
relevant. Human densities were very low (<0.5 inhab-
itants per km
2
) and the landscape consisted mainly of
woodland and mires. Open spots with low-intensity
agriculture were found only in the direct vicinity of
human settlements. At first these fields were created
by burning a certain area of woodland and used until
the nutrients were depleted, typically after a few
years, and then the settlements were broken up and
a new area was sought. There the whole cycle started
again (
slash and burn culture
). This
near-natural land-
scape
existed until the beginning of the Middle Ages
(
c
.500
AD
).
The next,
semi-natural
stage is associated with the
development of a more sedentary form of agriculture.
The settlements became fixed and human impact on
the landscape increased. Uniform landscapes were
split up, at least partly, and large-scale gradients
were replaced by smaller gradients of human impact.
Close to the villages human impact was sometimes
considerable whereas this influence became almost
negligible further away. This process continued with
time and human impact became ever more dominant.
In certain areas humans had altered the structure of
the landscape completely by the end of the Middle Ages
(
c
.1500
AD
), for example in England where most wood-
lands had been cut for fuel and people had to switch
to peat for heating. Another example is the western
part of the Netherlands where people started to pro-
tect themselves against flooding by building dykes and
creating polders from the 15th century onwards (Bos
et al.
1988). However, in general landscape use in
north-west Europe was more or less determined by
natural restrictions and remained semi-natural until
the end of the 19th century.
Developments in natural sciences stood at the basis
of the next phase with
industrial agriculture
and led
North America
To a certain degree the afore-mentioned developments
also occurred in North America. There are, however,
two major differences with Europe. First, the time-
scales are different. Whereas the natural situation
ended at the onset of the Middle Ages in Europe this
stage continued until the arrival of European settlers
in North America. Even then intensification occurred
on a comparatively small scale during the first two
centuries and was mainly restricted to the East Coast.
Large-scale developments in North America started
especially after colonization of the whole area by white
settlers in the second half of the 19th century, but
then developments took place at a much faster pace
than in Europe. One of the consequences was that the
semi-natural situation, which is a major reference for
ecological restoration in Europe, hardly occurred in
North America. In most regions the natural stage was
followed immediately by the industrial agricultural
phase. A clear example is the situation in the Mid-
West where prairies were converted directly into
intensively used arable fields, which almost led to
the extinction of large herbivores such as bison.
A second important difference between North
America and north-west Europe is the large difference
in human population size. Whereas the high popula-
tion density in Europe made it necessary also to pro-
duce food in less suitable areas with infertile soils,
insufficient moisture supply, etc., this was much less
the case in North America. Here land-use pressure was
much lower and food production could be restricted
to more favourable areas. An important consequence
is that larger areas with relatively untouched
