Summary

3.6. The potential earthworm impact on processes of soil eutrophication in the
forests of Jurmala and Saulkalne
Increase of the total earthworm population has impact on both the soil structure
and its fertility (Lee, 1985; Атлавините, 1990; Haimi, Boucelham, 1991; Deleporte,
Tillier, 1999; McInerney et al., 2001; Räty, Huhta, 2004). The earthworm population
increase may be related to the possible microorganism activization in the non-
degradated sampling plots in Jurmala and Saulkalne after additional nutritient
spreading into the forest soils due to the recreative load, optional activities and
pollution (Figure 3.3). Activity of microorganisms quickens decomposition of plant
residues, and greater amount of nutritients descend into the soil, creating favorable
circumstances for the earthworm population increase, and plant growth. In the gullets
of earthworms occurs formation of humus matter with more neutral pH reaction,
forming stable aggregates with soil mineral complexes. It reduces the processes of
soil podsolation (Аристовская, 1980; Стриганова, 1980). Especially active forest
plant residues recyclers and soil formers are Lumbricus rubellus, whose population
increase and the dominance in species communities have been observed in both-
Jurmala, and Saulkalne. Significant is formation of a stable population of endogeic
Aporrectodea caliginosa. Presence of earthworms may become a significant factor
for the further biocenosis development. Earthworms quicken different processes in
the soil, among them also formation of primary production, mineralization and
accumulation of nitrogene, formation of mull humus (Satchell, 1980; Стриганова,
1980; Tiunov, Scheu, 2004). It means that in the forest transformation processes in
both- Jurmala, and Saulkalne, more significant are the inner factors of the
biocenosis- the mutual incentive impact of microorganisms, earthworms and plants.
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