The principal regulators of vegetation structure in lakes of north-west Poland. A new approach to the assembly of macrophyte communities

TABLE OF CONTENTS

1. INTRODUCTION 7

Acknowledgements 10

2. METHODS 11

2.1. Plant sampling 11

2.2. Methods of environmental testing 12

2.3. Statistical analysis 13

3. VEGETATION STRUCTURE 18

3.1. Frequency and species abundance 18

3.2. Diversity of vegetation 28

3.3. Macrophyte communities 33

3.3.1. The Sphagnum denticulatum – Warnstorfi a exannulata community 33 3.3.2. The Isoëtes lacustris – Lobelia dortmanna – Littorella unifl ora

community 36

3.3.3. The Myriophyllum alternifl orum – Littorella unifl ora community 42 3.3.4. The Chara delicatula – Drepanocladus sordidus community 46 3.3.5. The Fontinalis antipyretica – Drepanocladus sordidus community 50 3.3.6. The Myriophyllum alternifl orum – Chara delicatula community 55

3.3.7. The Elodea canadensis community 59

3.3.8. The Ceratophyllum demersum community 64

3.3.9. The Myriophyllum spicatum community 68

3.3.10. The Nitella fl exilis community 73

3.3.11. The Chara globularis community 76

3.3.12. The Chara tomentosa community 80

3.4. Comparative analysis of the communities 86

4. FACTORS AND REGULATORS 97

4.1. Relationships between environmental factors,

communities and their toposequence 97

4.2. The rank of environmental factors 107

5. DISCUSSION 143

5.1. Abiotic regulators 143

6

5.1.1. Light intensity 143

5.1.2. Temperature 145

5.1.3. Nutrients 148

5.1.4. Dissolved inorganic carbon 149

5.1.5. Organic matter in the water 154

5.1.6. Sediment as a regulator 155

5.1.7. Water depth, hydrodynamic forces and human pressure 156

5.2. Biotic regulators of vegetation structure 158

5.3. Relationships among regulators 160

6. CONCLUSIONS 163

7. REFERENCES 165

8. SUMMARY (in Polish) 182

9. APPENDIX 197