Summary

CONTENTS
CONTENTS ................................................................................................................................................3
INTRODUCTION ......................................................................................................................................4
1. EARTHWORMS IN AGRICULTURAL LANDS...............................................................................9
1.1. EARTHWORM IMPACT ON SOIL PROPERTIES AND MICROORGANISMS...........................................11
1.2. EARTHWORMS AND SOIL CULTIVATION......................................................................................... 12
1.3. EARTHWORM IMPACT ON GRICULTURAL LAND QUALITY BIOINDICATION................................... 13
2. THE MONITORING SYSTEM OF AGRICULTURAL LANDS....................................................14
2.1. DESCRIPTIOM OF THE MONITORING SAMPLING PLOTS ................................................................ 14
2.2. FACTORS EFFECTING EARTHWORM DENSITY AND COMMUNITY STRUCTURE IN THE MONITORING
SAMPLING PLOTS .................................................................................................................................. 15
3. CHANGES OF EARTHWORM COMMUNITIES IN ACIDIC PINE FOREST SOILS ..............19
3.1. LATVIA’S OLIGOTROPHIC FOREST SOIL EARTHWORM FAUNA IN LATVIA AND NORTHERN EUROPE
.............................................................................................................................................................. 19
3.2. EARTHWORM FAUNA CHANGES DUE TO FOREST LIMING.............................................................. 21
3.3. LATVIA’S BOREAL PINE FOREST EUTROPHICATION AND TRANSFORMATION ............................... 22
3.4. EARTHWORM SPECIES COMMUNITIES CHANGES DUE TO TRANSFORMATION OF JURMALA
FOREST SOILS........................................................................................................................................ 23
3.4.1. Description of the sampling plots and sampling procedure ................................................... 23
3.4.2. The total earthworm population density in Jurmala sampling plots ...................................... 25
3.4.3. Soil property change impact on earthworm communities ...................................................... 26
3.4.4. Earthworm communities structure in Jurmala sampling plots............................................... 27
3.5. EARTHWORM COMMUNITIES CHANGE DUE TO THE INDUSTRIAL POLLUTION IN THE PINE
FORESTS NEAR SAULKALNE ................................................................................................................. 29
3.5.1. Description of the sampling plots and sampling procedure ................................................... 29
3.5.2. The total earthworm population in Saulkalne sampling plots................................................ 31
3.5.3. Pollution impact on the earthworm populations .................................................................... 34
3.5.4. The earthworm communities structure in Saulkalne sampling plots ...................................... 34
3.6. THE POTENTIAL EARTHWORM IMPACT ON PROCESSES OF SOIL EUTROPHICATION IN THE
FORESTS OF JURMALA AND SAULKALNE ............................................................................................. 36
3.7. ROLE OF EARTHWORMS IN THE BIOINDICATION OF THE PINE FOREST EUTROPHICATION
PROCESSES............................................................................................................................................ 37
CONCLUSIONS.......................................................................................................................................39
LITERATURE..........................................................................................................................................41
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