Report from the Sub-comittee on the environment and health

Scenarios with birds
Methods and calculations
fertiliser, 25 tonnes of pig manure per hectare were used, <strong>the</strong> density of
earthworms would increase by about 25%. For comparison, <strong>the</strong> density in
a clover-grass field is shown. There, <strong>the</strong> highest value is reached one year
after reploughing. It can thus be concluded that <strong>the</strong> density of
earthworms is not affected by <strong>the</strong> pesticides used in <strong>the</strong> scenario for
present production but is greatly affected by soil treatment, <strong>the</strong> use of
animal manure and, particularly, <strong>the</strong> crop rotation.
Scenarier
Scenarier med regnorme
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Kløvergræs
400
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Gylle 110
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Nul 99
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Nudrift
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88
0 100 200 300 400
Regnorme pr. kvadratmeter
Figure 10.5
Calculations of <strong>the</strong> average density of earthworms in present production
and <strong>the</strong> 0-scenario. For comparison, calculations are shown for <strong>the</strong>
average density with use of pig manure and <strong>the</strong> density in clover grass
one year after reploughing.
(Figure texts:
Scenarier = Scenarios
Scenarios with regnorme = Scenarios with earthworms
Kløvergræs = Clover grass
Gylle = Pig manure
Nul = 0-scenario
Nudrift = Present production
Regnorme pr. kvadratmeter = Earthworms per square metre)
There are a number of characteristic bird species in Danish farmland.
Their population development and distribution in <strong>the</strong> landscape have
been studied as an element of research on <strong>the</strong> impact of pesticides on
nature and <strong>the</strong> environment (Petersen, Jacobsen 1997). With this
knowledge it is possible to carry out simple calculations of how <strong>the</strong> bird
populations would develop in <strong>the</strong> different scenarios for land use and
pesticide use (Petersen, Jensen, 1998).
There have been some studies that do not directly contain data that can
be used for scenario analyses because <strong>the</strong>y cannot be generalised or have
been collected in conditions that do not reflect present-day Danish
agricultural conditions (Petersen, Jensen, 1998). The calculation used is
based on data <strong>from</strong> three years' counts of birds in <strong>the</strong> breeding season at
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