Ecology of mire vegetation located on fishpond's edges in Třeboň basin
(2002-2006)
- The dissertation contains a vegetation-environment study of mires on fishpond-margins in the Třeboň Basin (Czech Republic). Vegetation-environment relationships were investigated in mires that are enriched with nutrients and especially calcium, from intensely managed and limed fishponds. As a result, the extremely high longterm nutrient supply to the mires on fishpond margins has not altered the gradient structure, but has shifted the chemical limits of plant communities. Water pH and position of water table were identified as the two main determinants of species variation in fishpond-margin mires. Species richness of both vascular plants and bryophytes was partly explained by pH. However, the variation in total mineral richness and potassium concentration in the water were the next two most important variables determining bryophyte species richness. We observed some seasonal trends in the dynamics of the water parameters. The lowest electrical conductivity was recorded in spring, and it increased continuously throughout summer; becoming highest in autumn. In contrast, the water table was falling in summer, when evapotranspiration was high, and rose in autumn after heavy rainfall. Water pH increased from March to June, then it remained stable and decreased at the end of summer. The fluctuations of the environmental factors measured were wider in species-poor fen vegetation than they were in rich fens, which seemed to be quite stable in all environmental factors measured. The dissertation also includes the results of a test of the PVC discoloration method for measurement of the water table, and recommends a new alternative method, which works precisely even in fens and in mineral soils. Further, a comparison was made between two different methods usually used for monitoring vegetation changes: repeated vegetation sampling, and comparison of vegetation maps using GIS, taking the example of changes in a moderatelyrich fen after 20 years. The results of both methods showed successional changes to denser vegetation types. The difference between these two methods is in the scale. The first method provides more detailed information about species composition, but it can miss changes in spatial composition of the vegetation investigated. In this case, the other method is useful.
Publications for dissertation
- Navrátil J. & Navrátilová J. (2007): Wetlands succession in Ruda Nature Reserve, Czech Republic. – In: Okruszko S. T., Maltby E., Szatyłowicz J., Świątek D. & Kotowski W. (eds), Wetlands: Monitoring, Modelling, Management. Taylor & Francis Group, London, p. 27-36. (pdf)
- Navrátilová J., Navrátil J. & Hájek M. (2006): Relationships between environmental factors and vegetation in nutrient-enriched fens at fishpond margins. – Folia Geobot. 41: 353–376. (pdf)
- Dítě D., Navrátilová J., Hájek M., Valachovič M. & Pukajová D. (2006): Habitat variability and classification of the bladderwort (Utricularia) communities: comparison of peat depressions in Slovakia and Třeboň basin. – Preslia. 78: 331–343. (pdf)
- Navrátilová J. & Hájek M. (2005): Recording relative water table depth using PVC tape discoloration: Advantages and constraints in fens. – Appl. Veg. Sci. 8: 21–26. (pdf)
- Navrátilová J. & Navrátil J. (2005): Vegetation gradients in fishpond mires in relation to seasonal fluctuations in environmental factors. – Preslia 77: 405–418. (pdf)
- Navrátilová J. & Navrátil J. (2005): Hlavní typy nelesní rašeliništní vegetace Třeboňské pánve. – Sbor. Jihočes. Muz. v Čes. Budějovicích Přír. Vědy 45: 45–56. (pdf)
- Navrátilová J. & Navrátil J. (2005): Stanovištní nároky ohrožených a vzácných rostlin rašelinišť Třeboňska. – Zprávy Čes. Bot. Společ. 40: 279–299. (pdf)
- Navrátilová J. & Navrátil J., (2004): Rašeliništní vegetace v severní části třeboňsko-jindřichohradeckého pomezí. Sbor. Jihočes. Muz. v Čes. Budějovicích Přír. Vědy. 44: 45-58.