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sampling plots, density of Lumbricus rubellus is high in all seasons. Aporrectodea caliginosa were found only in greatly eutrophicated sampling plots. They were found almost in all seasons that indicate on formation of a constant Aporrectodea caliginosa population. Lumbricus castaneus is a typical forest species, and is not normally found in acidic pine forest soils with pH value less than 4 (Атлавините, 1976). In Jurmala Lumbricus castaneus were found almost in all seasons in the eutrophicated sampling plots, it may be due to both the decrease of soil acidity and the incres of nutrition source- leave and vascular plant waste in the ground cover. Table 3.3 Communitie of earthworms in Jūrmala sample plots in forests with different degrees of eutrophication *(Атлавините, 1976; unpublished data of author on earthworm fauna of oligotrophic maritime pine forests in Western Latvia) Observation site Communities of earthworms Natural pine forests * Dendrobaena octaedra Not transformed forests in Jūrmala Dendrobaena octaedra – Lumbricus rubellus Forests with partial eutrophication in Dendrobaena octaedra – Lumbricus rubellus Jūrmala Lumbricus rubellus – Dendrobaena octaedra – Aporrectodea caliginosa Eutrophicated forests in Jūrmala Lumbricus rubellus – Dendrobaena octaedra – Lumbricus castaneus - Aporrectodea caliginosa To the non-eutrophicated sampling plots of Jurmala characteristic are communities of two earthworm species Dendrobaena octaedra and Lumbricus rubellus with little dominance of Dendrobaena octaedra (Tables 3.2 and 3.3). It should be considered that formation of a stable Lumbricus rubellus population indicates on the beginning of the eutrophication processes in these sampling plots. In the partly eutrophicated sampling plots, increases dominance of Lumbricus rubellus. Dominance of both Dendrobaena octaedra and Lumbricus rubellus here is analagous. In the greatly eutrophicated areas appears typical dominace of Lumbricus rubellus, but reduces dominance of Dendrobaena octaedra. Increases also population 28
of Aporrectodea caliginosa, emerge new earthworm species noncharacteristic to the pine forest soils. Here are formed 3 to 4 earthworm species communities, who are characteristic both- to conifer, and deciduous tree forests. They are considered as a transition type species communities characterizing forest eutrophication processes. In the non-eutrophicated pine forest soils such species communities have not been found. 3.5. Earthworm communities change due to the industrial pollution in the pine forests near Saulkalne Saulkalne dolomite processing plant yearly emits into the atmosphere more than 700 t of pollutants. In the 80’s of the last century, the production units functioned in full load, but in the turn of the 80’s and 90’s, the production capacity was rapidly decreased. The most common pollutants in the exausted emissions of the factory are the dust containing calcium and magnesium compounds. Till 1995, when installation of inovative purification filters was initiated the company operated without strict requirements on the environmental protection (Vaivara, 2006). 3.5.1. Description of the sampling plots and sampling procedure In order to determine the effect of the pollution created by Saulkalne dolomite processing plant, in 1989 near the industrial area of Saulkalne were initiated lasting observations on the forest dynamic. In the dominant wind direction for 6.3 km was established transect with 5 sampling plots at different distances from the dolomite processing factory (Table 3.4). The sampling plots were created in areas, which conform to Vaccinio myrtilli – Pinetum forest growth type. The forest stand age in 1989 was assessed to be from 41 to 63 years. Earthworms were sampled in the period from 1989 to 1991. The soil of the sampling plots is formed of fine-grained sand. Organic matter and humus accumulation horizon number in the first two sampling plots, closest to the emission source, is higher (O, Ah, AhE). In these sampling plots, mineralization of the organic 29
Page 1 and 2: UNIVERSITY OF LATVIA FACULTY OF GEO
Page 3 and 4: CONTENTS CONTENTS .................
Page 5 and 6: environmental factors, as well as o
Page 7 and 8: Aprobation of te Results Te results
Page 9 and 10: 1. EARTHWORMS IN AGRICULTURAL LANDS
Page 11 and 12: Summing up data of numerous researc
Page 13 and 14: 1.3. Earthworm impact on gricultura
Page 15 and 16: period. The samples were hand sorte
Page 17 and 18: Figure 2.1. All season mean density
Page 19 and 20: 3. CHANGES OF EARTHWORM COMMUNITIES
Page 21 and 22: ubidus tenuis, whose propotion is i
Page 23 and 24: soil liming has facilitated great b
Page 25 and 26: 3.4.2. The total earthworm populati
Page 27: population of earthworms in all of
Page 31 and 32: Table 3.5 The chemical properties o
Page 33 and 34: For the reciprocal comparision of t
Page 35 and 36: observed by the author of the docto
Page 37 and 38: Figure 3.3. Possible process of pin
Page 39 and 40: CONCLUSIONS 1. Reasearches conducte
Page 41 and 42: LITERATURE Abrahamsen, G. 1972. Eco
Page 43 and 44: Latvian Academy of Sciences, B, 7 (
Page 45: беспозвоночныхмор

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