Summary

For the reciprocal comparision of the sampling plots the average density of
worms in all seasons was chosen (Figure 3.2). In comparision with natural forests of
similar growth type, the average earthworm density in Saulkalne sampling plots is
relatively high. Even in the monitoring sampling plot with vegetation corresponding
to a natural forest type, the density in all seasons is heightened. Obsviously, also in
Saulkalne sampling plots, changes in the earthworm populations are observed before
changes in the vegetation.
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6
4
2
0
Saulk 1 Saulk 2 Saulk 3 Saulk 4 Saulk 5
Figure 3.2. All season mean density of earthworms per sample in Saulkalne sample plots.
In highly transformed forests, closer to the emission source, the earthworm
population has a tendency to increase. In the closest sampling plot to the factory, the
density is little lower than in the next two, what may be due to the emited pollution
of factorie in they direct closiness. In the both furthest sampling plots, where the soil
pollution level is lower, the earthworm density is lower. However, ANOVA analysis
did not show significant differences among the sampling plots.
Comparing seasonal earthworm changes, it is evident, that in the sampling
plots Saulkalne 1 and Saulkalne 2, the density gradually increases. Such a
nonchaectaristic earthworm population dynamics to the pine forest biotypes
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