Vegetation-environment relationships in alpine mires of the West Carpathians and the Alps

QuestionsHow do two distant mountain ranges differ in their vegetation-environment relationships, overall species composition and its variability and species richness of vascular plants and bryophytes in alpine fens and bogs? Is the floristic difference consistent along the acidity-alkalinity gradient? LocationWest Carpathians (Poland, Slovakia) and Swiss Alps. MethodsVascular plant and bryophyte species compositions and environmental characteristics were sampled along the large acidity-alkalinity gradient within the alpine belts. PERMANOVA was used for testing floristic differences between the regions, DCA for the patterns description, CCA for testing the vegetation-environment relationships and linear models for testing the local species richness determinants. Compositional -diversity (rate of compositional turnover) and regional species pool were compared using PERMDISP and sample-based rarefaction curves. ResultsMost floristic variation was explained by water pH in both regions. Macroclimate was the second most important gradient in the Alps, correlating with the second DCA axis delimiting the moderately poor brown-moss fens from the Sphagnum bogs. The species composition differed significantly between the regions in all three pH classes, expect for bryophytes in the middle pH class. Bryophytes exhibited higher similarities between the regions, except in acidic mires. Vascular plant composition differed most in the middle pH class. The local species richness was predominantly determined by pH, except for bryophytes in the Alps. As compared to bryophytes, vascular plant local species richness was affected by more factors and showed a clear linear response to pH. Within the particular pH classes, there were few differences in local species richness, compositional -diversity and regional species pool between the two mountain ranges. ConclusionsThe pattern in inter-regional floristic dissimilarities differs between bryophytes and vascular plants, probably because of better dispersal ability of bryophytes, and different causes of these dissimilarities: lower mass effect at extreme ends of the acidity-alkalinity gradient in the case of vascular plants and higher compositional -diversity of acidic mires in the case of bryophytes. Contrary to previously explored alpine springs of the same regions, local species richness and composition were determined rather by pH than mineral richness, and all patterns were more consistent between the regions and the taxonomic groups.

Patterns of bryophyte and vascular plant richness in European subalpine springs

Alexandre Buttler, Lucia Sekulova

The diversity of spring habitats can be determined not only by local environmental conditions, but also by large-scale biogeographical effects. The effects can differ across various groups of organisms. We compared alpha-, beta- and gamma-diversity patterns of bryophytes and vascular plants of (sub)alpine springs in three contrasting mountain ranges: Alps (Switzerland), Balkans (Bulgaria), Western Carpathians (Slovakia, Poland). We used univariate and multivariate statistics to test for the effects of pH, conductivity, altitude, slope, mean annual temperature and annual precipitation on diversity patterns of both taxonomic groups and compared diversity patterns among the regions for particular pH and conductivity classes. We identified acidophyte and basiphyte, calcifuge and calcicole species using species response modelling. All regions displayed significant relationship between conductivity and alpha-diversity of vascular plants. Bulgaria showed the highest alpha-diversity of vascular plants for the middle part of the conductivity gradient. For both taxonomic groups, the beta-diversity in the middle part of gradient was highest in Swiss Alps. The total species pool was lowest in Bulgaria. The percentage of basiphyte and calcicole species was highest in the Alps. In (sub)alpine springs, mineral richness was a better determinant of vascular plant alpha-diversity than pH, and the extent of the alpine area did not coincide with alpha-diversity. Observed inter-regional differences in diversity patterns could be explained by the different proportion of limestone bedrock and different biogeographic history. The differences in alpha-diversity between both taxonomic groups are presumably result of the different rates of adaptation processes.

Springer Netherlands2012

Changes in testate amoebae (Protists) communities in a small raised bog. A 40-year study

Edward Mitchell

We analyzed the testate amoebae communities from two sets of moss samples taken forty years apart (1961 and 2001) in the same locations of a peat bog of the Swiss Jura Mountains. Peat cutting and lateral drainage of Le Cachot bog have caused a clear increase in tree cover, especially near the edges. Changes affecting herbaceous plants, mosses, or soil organisms can be subtle, and may easily be overlooked. We hypothesized that we would see changes in the dominant Sphagnum species and the structure of testate amoebae communities living in the mosses. More specifically, we hypothesized that the frequency of bryophyte and testate amoebae species indicative for dry conditions would increase and that the frequency of species indicative for wet conditions would decrease. The mean testate amoebae species richness per sample decreased from 11.9 to 9.6, but the overall species richness was identical (33 species) in both years. Three species increased significantly in mean relative abundance: Nebela tincta s.l. (+97%), Bullinularia indica (+810%), and Cyclopyxis eurystoma (+100%; absent in 1961), while two species decreased significantly: Assulina muscorum (-63%) and Euglypha compressa (-93%). The testate amoebae communities clearly differed among microhabitat types (hummocks, lawns, hollows), but no overall significant change in the community was detectable between the two sampling dates (Mantel test). These results could signify that changes at the microscopic level had already taken place by 1961 and no further overall significant changes in micro-environmental conditions took place during the 40-year period of this study. This would agree with the faster response time usually attributed to microorganisms and would also imply that the bushes and trees may be poor predictors of the response of microorganisms if they are themselves in a non-equilibrium stage. Other possible causes for the lack of overall differences are discussed.

2005

Plant species richness and environmental heterogeneity in a mountain landscape: effects of variability and spatial configuration

Alexandre Buttler

The loss of biodiversity has become a matter of urgent concern and a better understanding of local drivers is crucial for conservation. Although environmental heterogeneity is recognized as an important determinant of biodiversity, this has rarely been tested using field data at management scale. We propose and provide evidence for the simple hypothesis that local species diversity is related to spatial environmental heterogeneity. Species partition the environment into habitats. Biodiversity is therefore expected to be influenced by two aspects of spatial heterogeneity: 1) the variability of environmental conditions, which will affect the number of types of habitat, and 2) the spatial configuration of habitats, which will affect the rates of ecological processes, such as dispersal or competition. Earlier, simulation experiments predicted that both aspects of heterogeneity will influence plant species richness at a particular site. For the first time, these predictions were tested for plant communities using field data, which we collected in a wooded pasture in the Swiss Jura mountains using a four-level hierarchical sampling design. Richness generally increased with increasing environmental variability and "roughness" (i.e. decreasing spatial aggregation). Effects occurred at all scales, but the nature of the effect changed with scale, suggesting a change in the underlying mechanisms, which will need to be taken into account if scaling up to larger landscapes. Although we found significant effects of environmental heterogeneity, other factors such as history could also be important determinants. If a relationship between environmental heterogeneity and species richness can be shown to be general, recently available high-resolution environmental data can be used to complement the assessment of patterns of local richness and improve the prediction of the effects of land use change based on mean site conditions or land use history.