Abstract
Recently available extensive datasets on plant distributions across the whole national floras and on functional traits of such floras and increasing availability of fine-scale information on the abiotic environment make it possible to explore the trends in plant traits across geographical space and explain them as a function of large-scale environmental factors. Our aim is to define the main axes of variation in plant traits as surrogates for functional strategies and to test how functional trends vary with changing environmental factors at a large scale.
We used the Pladias Database of the Czech Flora and Vegetation to extract plant composition in cells of 5 longitudinal minutes x 3 latitudinal minutes covering the whole country. We also extracted 79 species traits and calculated Principal Coordinate Analysis based on the Gower weighed distance among species, defined by their traits.
We then used species composition of cells to calculate the average of scores for each of the first four ordination axes and mean trait dissimilarity within a cell as a measure of functional diversity. The functional trends (score averages and trait dissimilarity) were plotted on the country map to facilitate the interpretation of trends.
We also related each of the functional trends to large-scale environmental factors such as precipitation, temperature, topographic wetness and bedrock using linear models. The first four axes of the ordination represented approx. 30% of the total variation in traits.
The first axis separated the annual herbs occurring mainly in warm lowlands vs perennial, clonal herbs or dwarf shrubs occurring mainly in cool and wet mountain areas, which are mostly formed of nutrient-poor rocks and have a larger representation of forest in the landscape. The second axis contrasted species with short-living shoots, large SLA, including hydrophytes, geophytes, in general R strategists and species more related to wetlands vs species with long-living shoots, large leaves with high dry matter content, usually C or S strategists with a higher presence in mesic/dry areas.
The third axis reflected the difference between species with simple persistent-green leaves, prevailing dicyclic or polycyclic shoots in warm wetland areas, and those with compound summer-green leaves with monocyclic shoots in the areas with relatively high precipitation, poor soils and low temperatures. The fourth axis contrasted windpollinated species with fleshy fruits, often trees or shrubs, generally S strategists, related to the areas with acidic, nutrient-poor soils (submontane and montane landscapes on base-poor ancient rocks, also slightly cooler and precipitation richer) vs insect-pollinated species with dry fruits (lowland areas with Cretaceous and younger sediments, with more base-rich and nutrient-rich soils).
Functional diversity within cells is higher in warm areas with low precipitation and outside wetlands.