Die Ruderalvegetation des nördlichen Teils der Donau-Tiefebene 3. Gesellschaften des Verbandes Dauco-Melilotion auf natürlichen Standorten

Echio-Verbascetum Sissingh 1950, Epilobio dodonaei-Melilotetum albae Slavík 1978 und Erysimo-Galeopsietum angustifoliae Mucina 1982 gehören zur Gruppe von Gesellschaften des Verbandes Dauco-Melilotion Görs 1966 auf natürlichen Standorten, d.h. im Falle der Donau-Tiefebene auf Flusskiesbänken. Im mittleren Pova?ie-Gebiet kommen diese Gesellschaften entlang des Váh-Flusses vor, wobei sie typische Zonationssysteme bilden. Sie sind die artenreichsten Gesellschaften des Verbandes, ihre Artenzahl erreicht sogar Werte von 47–49 (Echio-Verbascetum). Die Lactuca viminea-Artemisia campestris-Gesellschaft ist im Untersuchungsgebiet selten. Sie besiedelt halbruderale Standorte—ruderalisierte Bergfüsse unter Abhängen. Zu den grundlegenden Charakteristika der Gesellschaften gehört auch der hohe Anteil thermophiler und xerophiler Arten der Klasse Sedo-Scleranthetea und Festuco-Brometea, als auch der Anteil von Arten skelettreicher Substrate (Arten der Klasse Thlaspietea rotundifolii).     

DasAnthriscetum sylvestris in der Slowakei

DasAnthriscetum sylvestris Hada? 1978 (VerbandAegopodion podagrariae), eine expanaive Ruderalgesellschaft, wurde auf Grund von 36, aus der ganzen Slowakei stammenden, Vegetationsaufnahmen charakterisiert. In Bezug auf die floristische und ökologische Diversität wurden die folgenden neuen Syntaxa ausgeschieden:A. s. brometosum sterilis (mit der typischen Variante und der Variante mitPoa nemoralis) undA. s. poëtosum trivialis (mit der typischen Variante und der Variante mitRanunculus repens). Die syntaxonomischen und syndynamischen Beziehungen der Assoziation werden diskutiert.     

Quantifying the effects of ecological constraints on trait expression using novel trait‐gradient analysis parameters

Complex processes related to biotic and abiotic forces can impose limitations to assembly and composition of plant communities. Quantifying the effects of these constraints on plant functional traits across environmental gradients, and among communities, remains challenging. We define ecological constraint (C_i) as the combined, limiting effect of biotic interactions and environmental filtering on trait expression (i.e., the mean value and range of functional traits). Here, we propose a set of novel parameters to quantify this constraint by extending the trait‐gradient analysis (TGA) methodology. The key parameter is ecological constraint, which is dimensionless and can be measured at various scales, for example, on population and community levels. It facilitates comparing the effects of ecological constraints on trait expressions across environmental gradients, as well as within and among communities. We illustrate the implementation of the proposed parameters using the bark thickness of 14 woody species along an aridity gradient on granite outcrops in southwestern Australia. We found a positive correlation between increasing environmental stress and strength of ecological constraint on bark thickness expression. Also, plants from more stressful habitats (shrublands on shallow soils and in sun‐exposed locations) displayed higher ecological constraint for bark thickness than plants in more benign habitats (woodlands on deep soils and in sheltered locations). The relative ease of calculation and dimensionless nature of C_i allow it to be readily implemented at various scales and make it widely applicable. It therefore has the potential to advance the mechanistic understanding of the ecological processes shaping trait expression. Some future applications of the new parameters could be investigating the patterns of ecological constraints (1) among communities from different regions, (2) on different traits across similar environmental gradients, and (3) for the same trait across different gradient types.     

Habitat heterogeneity promotes intraspecific trait variability of shrub species in Australian granite inselbergs

The role of intraspecific trait variability is increasingly recognized as a key factor shaping plant fitness and community assembly worldwide. Studying the direct effects of habitat heterogeneity on trait expression of individual plants of the same species is a useful tool to quantify intraspecific trait variability locally. We investigated how habitat heterogeneity on granite inselbergs affected intraspecific trait variability of 19 functional traits in three shrub species of the family Proteaceae in south western Australia, a global biodiversity hotspot. We used pairwise comparison (single trait) and multivariate analysis (multiple traits, functional space) to detect shifts in trait patterns. Consistent with our predictions, we found that individuals developing in putatively more stressful habitats (highly sun-irradiated, shallow-soil patches on the outcrops) were characterized by trait expressions indicative of more conservative resource-related strategies when compared with plants occurring in the surrounding woodlands that were experiencing more benign ecological conditions. These results were significant for two out of three species. Granite inselbergs promoted plant longevity, a signal that these granite inselbergs might offer refugial conditions defined as protection against fire.     

A numerical-taxonomic study of theJuncus bufonius aggregate (Juncaceae) in Slovakia

Samples of 34 populations of theJuncus bufonius aggregate in Slovakia have been submitted to a numerical-taxonomic treatment. Three species corresponding to three known cytodemes, i.e.J. bufonius L. s. str. (2n = c. 100–110),J. ambiguus Guss. (2n = 34) andJ. minutulus (Alb. etJahan.)Prain et al. emend.Snog. (2n = c. 72), have been confirmed for the study area. A survey of quantitative characters by various ordination and cluster techniques reveals that the length of capsules, seeds, inner tepals and anthers as well as the ratio of anther to filament length are significant for the segregation of the cytodemes.     

Woody species in resource‐rich microrefugia of granite outcrops display unique functional signatures

Refugia are key environments in biogeography and conservation. Because of their unique eco‐evolutionary formation and functioning, they should display distinct functional trait signatures. However, comparative trait‐based studies of plants in refugia and non‐refugia are lacking. Here, we provide a comparison between resource‐rich (putative microrefugia for species preferring mesic habitats under increasing aridity) and resource‐impoverished woodlands (non‐refugia) around two granite outcrops in south‐western Australia. We measured and compared six functional traits (bark thickness, foliar δ¹³C, foliar C:N, leaf dry matter content, plant height, specific leaf area) in four woody species. We performed multiple‐trait, multiple‐species and single‐trait, within‐species analyses to test whether plants in resource‐rich habitats were functionally distinct and more diverse than those in the surrounding resource‐impoverished woodlands. We found that species in resource‐rich woodlands occupied larger and distinct multiple‐trait functional spaces and showed distinct single‐trait values (for specific leaf area and bark thickness). This suggests that plants in resource‐rich woodlands can deploy unique and more diverse ecological strategies, potentially making these putative microrefugia more resilient to environmental changes. These findings suggest that species in microrefugia may be characterised by unique functional signatures, illustrating the utility of comparative trait‐based approaches to improve understanding of the functioning of refugia.     

Tri-substituted imidazole analogues of SB203580 as inducers for cardiomyogenesis of human embryonic stem cells

The p38α mitogen-activated protein kinase (MAPK) inhibitor SB203580 had been reported to enhance the cardiomyogenesis of human embryonic stem cells (hESCs). To investigate if tri-substituted imidazole analogues of SB203580 are equally effective inducers for cardiomyogenesis of hESCs, and if there is a correlation between p38α MAPK inhibition and cardiomyogenesis, we designed and synthesized a series of novel tri-substituted imidazoles with a range of p38α MAPK inhibitory activities. Our studies demonstrated that suitably designed analogues of SB203580 can also be inducers of cardiomyogenesis in hESCs and that cell growth is affected by changes in the imidazole structures.