Geobotany

The Working Group of Vegetation Science focused its research in 1999-2004 on the following five topics:

1. Methods of formalized vegetation classification. The Working Group of Vegetation Science at Masaryk University manages one of the world?s largest databases of vegetation plots: the Czech National Phytosociological Database (Chytrý & Rafajová 2003). As vegetation databases are new resources for plant ecology and macroecology, the methods of their analysis are not yet sufficiently explored. A part of the research capacity of the working group was therefore focused on testing and development of new analytical methods. One of the main results includes the adaptation of the Cocktail classification method, originally developed by H. Bruelheide (Kočí et al. 2003). This method enables creation of formal definitions of plant communities and a consistent application of these definitions in large vegetation-plot data sets. The Cocktail method was implemented in the newly developed software JUICE (Tichý 2002), which is currently used in a number of laboratories in the Czech Republic, Europe and overseas. Properties of the Cocktail method were tested with real data sets of subalpine tall-forb vegetation (Kočí et al. 2003) and weed vegetation (Lososová 2004). The Cocktail method was supplemented with a newly developed procedure for similarity-based assignment of new plot records to the classes of an existing classification (Kočí et al. 2003, Tichý 2005). The second main result was the development of statistical measures of phytosociological fidelity (Chytrý et al. 2002a), which were successfully tested and used for determination of diagnostic species in different vegetation types. These developments made it possible to carry out an extensive parametrization of vegetation units and vascular plant species of the Czech Republic with respect to their diagnostic capacity. The parametrization results were published as a separate monograph (Chytrý & Tichý 2003). Statistically defined fidelity was also applied for the assessment of the quality of vegetation unit delimitation in the expert classifications (Chytrý & Tichý 2003) and for determination of the optimal number of clusters in a numerical classification (Botta-Dukát et al. 2005). In association with the application of formalized classification methods, some research was done into the assessment of data quality in phytosociological databases, with special attention to the effect of plot size (Chytrý 2001, Chytrý & Otýpková 2003). At the same time pilot studies of the scale effect on the determination of diagnostic species were performed (Chytrý et al. 2002b).
2. Studies of vegetation patterns at national and regional scale. Vegetation diversity and its relationships to abiotic factors and phytogeographical influences were studied in different vegetation types. All the studies were based on large vegetation-plot data sets and their principal objective was identification of major gradients in species composition, underlying environmental factors and searching for optimal classification that would be related to the previous schemes of vegetation and habitat classification. In particular, attention was paid to woodland, grassland and weed vegetation. In woodlands, diagnostic species of Central European spruce forests were identified (Chytrý et al. 2002), classification of Czech oak-hornbeam forests was revised (Knollová & Chytrý 2004) and an international publication on the diversity of circumpolar boreal forests of Euroasia and North America was edited (Chytrý & Spribille 2002, Spribille & Chytrý 2004). In grasslands, the diversity of hay-meadow vegetation of the Czech Republic was revised (Havlová et al. 2004), vegetation-environment relationships in Czech wet meadows were analysed (Hájek & Hájková 2004) and major gradients of diversity in lowland wet meadows in Central Europe were described (Botta-Dukát 2005). In weed vegetation, major environmental gradients responsible for its differentiation in the Czech and Slovak Republics were identified and described (Lososová 2004, Lososová et al. 2004).
3. Long-term dynamics of Central European vegetation types. Vegetation dynamics were assessed on the time scale ranging from several decades (using resampling of old vegetation-plot records) to a few years (using permanent plots). Research was mainly concerned with vegetation types dominated by annual plants which exhibit the highest dynamics and sensitively reflect environmental changes. Weed communities of arable land (Lososová 2003, Lososová et al. 2003, 2004, Pyšek et al. 2004b, 2005), human-made urban vegetation (Pyšek et al. 2004a) and annual wetland vegetation (Šumberová et al. 2005) were selected as the most suitable models. In arable weed communities, long-term decrease in diversity was revealed for the period of last few decades. This decrease was stronger at higher altitudes and mainly affected the archaeophytes, i.e. old alien species that migrated to Central Europe between the Neolithic and the Middle Ages. The same trend for archeophytes was found in urban vegetation. Besides annual vegetation, vegetation dynamics were also studied in perennial heathland vegetation after experimental disturbance that was used to simulate different types of nature conservation management (Chytrý et al. 2001). In this case disturbance resulted in an increase in species richness and enhancement of the nature conservation value of the studied sites.
4. Mire ecology. A detailed vegetation research connected with sampling of environmental data allowed to evaluate vegetation-environment relationships in the Western Carpathian mires at a broad geographical scale. Strong relationships between water chemistry and vegetation composition of fens was found at the landscape scale in the Outer-Carpathian flysch zone (Hájek et al. 2002); the same trend is evident from the analysis of large phytosociological data-set from the entire Western Carpathians (Hájek 2002). This result cannot be, however, extrapolated to a finer spatial scale, where water regime is more important (Hájková et al. 2004). Some mires are characterised by a very fine mosaic of contrasting microhabitats; therefore the area of a conventional phytosociological plots covers a long gradient in terms of both species composition and pH (Hájková & Hájek 2004b). The same scale-dependence as well as dependence on the taxonomical group studied (vascular plants, bryophytes) was confirmed also for correlations among species richness, aboveground biomass and water chemistry (Hájková & Hájek 2003). Some studies were devoted to the influence of seasonal dynamics of water chemistry and water level on the reliability of vegetation-environment correlation obtained from single measurements. The water pH and conductivity as well as water Ca concentration were found to be appropriate for characterising fen, especially rich fen, habitats even when single measurements are used. On the contrary, fluctuating concentration of iron and macroelements (N, P, K) is responsible for failed correlation with the species composition in the analyses of single measurements (Hájek & Hekera 2004, Hájková et al. 2004). Further research was focused on understanding the Sphagnum distribution and niche differentiation in the Western Carpathians. We succeeded in collecting concurrently measured data on water chemistry and water regime of Sphagnum microhabitats throughout a wide geographical range covering an area of thousands of square kilometers (Hájková & Hájek 2004a). We also started the research on concordances among species compositions of various taxonomical groups (vascular plants, bryophytes, algae, fungi, testate amoabeae, molluscs). The close indicative relationships was found namely between higher plants and molluscs (Horsák & Hájek 2003).
5. Local field studies of vegetation types. Local field studies of vegetation differentiation make up an integral part of vegetation science, as they provide basic data for large-scale synthetic studies of vegetation patterns and processes. Field research focused on the areas with insufficient or lacking data, and covered different vegetation types of the Czech Republic and adjacent countries. Individual studies included the Podyjí/Thayatal National Park (Chytrý & Vicherek 2003), Pavlov Hills, confluence area of the Morava and Dyje rivers (Vicherek et al. 2000) and the Bílé Karpaty Mts. (Otýpková 2001).