Wetland vegetation in the sub(alpine) zone of the West Carpathians (Poland, Slovakia) was studied with particular reference to the following questions: (i) What are the main types of (sub)alpine fen, bog and spring vegetation above the timberline in the West Carpathians? (ii) Which major environmental gradients are associated with the variation in floristic composition? (iii) What determines the α-diversity of bryophytes and vascular plants in the different vegetation types? Vegetation plots were sampled and direct measurements of certain environmental characteristics recorded. Cluster analysis was used to distinguish the vegetation types, DCA and CCA to reveal the main vegetation gradients and environmental factors, and general regression models to identify the factors determining the α-diversity. Classification at the level of 12 clusters was ecologically and syntaxonomically interpretable. Two associations not mentioned in the most recent vegetation survey of Slovakia were distinguished and the syntaxonomical positions of others revised. The synthesis of collected and published vegetation data for the two countries has modified the classification concept of (sub)alpine wetlands in the West Carpathians. Whereas pH predominantly determined floristic differences among classes, different factors governed the species composition within classes. While the diversity of the vegetation of springs (Montio-Cardaminetea) was mostly determined by water chemistry, altitude and geomorphology appeared to be more important within fens and bogs. The species richness of spring vegetation was more influenced by mineral richness than water pH and for bryophyte richness the slope inclination was also important. The species richness of fens and bogs increased with pH. It is concluded that the ecological gradients influencing the floristic composition and species richness of (sub)alpine wetlands are strongly habitat-dependent.
Vegetation analyses (phytosociological relevés) of 20 peat bogs arranged along an altitudinal gradient in the southern part of the Czech Republic, Central Europe, revealed relationships between vegetation and environmental gradients. Six of the peat bogs were investigated in detail. The bogs were dominated by Pinus rotundata, a species endemic to Central Europe, and its hybridogenous populations with P. mugo (the hybrid is called P. ×pseudopumilio), with increasing proportions of the latter at higher altitudes. Data were processed using indirect (DCA) and direct (CCA) gradient analyses. Environmental variables (depth of the water table, mean and minimum temperatures, precipitation, pH, conductivity, NH4 and PO4 concentrations, total P, but not total N nor NO3 concentration), as well as biotic characteristics of the sites, such as species composition, and growth form of the dominant pines, were closely correlated with altitude. Woody species, herbs and bryophytes responded to the altitude similarly. Results also indicated the unique characteristics of each bog.
Whittaker was one of the leading ecologists of his generation, introducing several ideas to plant community ecology. One approach involved deriving environmental-correlation curves in attempts to determine how the abundance of individual species changed along environmental gradients. These curves have been used extensively in the ecological literature of the last 50 years. However, there has been no examination of whether the methods used were sufficiently rigorous to justify Whittaker’s conclusions, let alone the very widespread use of them by others to draw general conclusions. Whittaker’s curves were based on large amounts of fieldwork. However, the sampling methods used were subjective, and the analyses of the data were often circular. When the curves are compared to the data on which they were based, it can be seen that many of the features that Whittaker claimed to see in his graphs are not supported. Whittaker’s main conclusions may have been correct but his studies do not stand up as pieces of scientific work.
We discuss and criticise the contention of Colombo (2012) that the central-marginal model does not apply to three species of chromosomally polymorphic acridid grasshoppers, and that chromosomal clines in these species are a consequence of temperature gradients. We also discuss Colombo’s interpretation of our own results on the South American melanopline grasshopper, Dichroplus pratensis Bruner., Claudio J. Bidau, Dardo A. Martí., and Obsahuje seznam literatury