"Folia Geobotanica"

Chiarucci, Alessandro;Calderisi, Marco;Casini, Francesca;Bonini, Ilaria

doi: 10.1007/s12224-008-9002-0pmid: N/A

Abstract The effects of the chemical and physical factors associated with geothermal activity on plant community structure and composition were investigated in one of the largest geothermal fields of central Italy. The study site was located in the geothermal area of Sasso Pisano – Monte Rotondo Marittimo, Southern Tuscany. The percentage cover of all vascular plant, bryophyte and lichen species was estimated within 119 circular plots of 0.25 m2. For each plot the soil pH, soil temperature, slope, aspect, incident radiation, soil nitrogen and carbon contents were also quantified. Two vascular plants, Calluna vulgaris and Agrostis castellana, were found to be the most widespread species tolerating the harshest conditions in terms of low soil pH and high soil temperature. The most widespread cryptogam species was Hypnum cupressiforme. Spatially autoregressive models showed that a proportion of about 41–51% of the variance in species richness of one group of plants (vascular or cryptogamic plants) could be modelled by using three or four uncorrelated environmental factors respectively (soil temperature, soil nitrogen and soil C/N ratio and these three plus incident radiation). For the total number of species (vascular and cryptogamic plants), the variance explained by the same three uncorrelated variables was about 57%. This study evidenced a strong environmental control of community composition and species richness, in a site subjected to extreme soil values of soil pH and temperature. The dominance of vascular over cryptogamic vegetation in this geothermal site can be explained by the combined effects of geothermal stress (low soil pH and high soil temperature) with the summer drought typical of the Mediterranean climate.

Liu, Hongyan;Ji, Zhongkui;Tian, Jun

doi: 10.1007/s12224-008-9003-zpmid: N/A

Abstract The complicated desert vegetation pattern and its links to soil conditions in the Manas River basin where the natural landscape and human land-use history are representative for NW China and even central Asia are quantitatively investigated in this study. Vegetation and soil of 47 remnant desert and 22 cropland stands along the Manas River were sampled. Soil features, including Total Organic Carbon (TOC), total and individual (\({\text{HCO}}_3^ - \), \({\text{CO}}_3^{2 - } \), Cl−, \({\text{SO}}_4^{2 - } \), K+, Na+, Ca2+, Mg2+) salt content, and physical components of both remnant desert and cropland stands were analyzed in a laboratory. In total, eight types of desert and lowland marsh communities are distinguished. Topographical conditions are found to strongly affect soil features. The topsoil is also distinguishable from the subsoil, particularly in clay content. Statistical analyses demonstrate that both silt percentage and total salt content in the soil are significant for the distribution of plant communities. Discriminant functions for the main desert and lowland marsh types were established based on their subsoil features, with accuracy up to 83%. The vegetation patterns prior to massive cultivation of 22 cropland plots were reliably interpreted from the cropland subsoil features using these discriminant functions. Twenty of them coincide very well with topological conditions, place names and records in literature, further confirming that the subsoil features have not substantially changed in the shifting from desert to cropland.

Kučerová, Andrea;Rektoris, Ladislav;Štechová, Táňa;Bastl, Marek

doi: 10.1007/s12224-008-9006-9pmid: N/A

Abstract Pinus rotundata dominated peatbog (Žofinka Nature Reserve) in the Třeboň Basin, Czech Republic, was affected by “natural” disturbances: wind damage (1984), followed by a bark beetle attack, and fire (1994, 2000). Phytosociological relevés were used to document vegetation. Soil water chemistry was compared in three differently affected stands: (1) an undisturbed Pinus rotundata bog forest, (2) a windthrow – bark beetle affected stand and (3) a site burned by wildfire in 2000. The species composition of the windthrow – bark beetle affected sites and the undisturbed P. rotundata bog forest differed mainly in the shrub and tree layers. Burned sites were partly colonized by anemochorous species (e.g. Taraxacum sp. div.) that disappeared within two or three years after colonization. Bare peat was colonized by bryophytes (e.g. Marchantia polymorpha and Funaria hygrometrica) typical of the disturbed sites, and by Polytrichum sp. div. and Aulacomnium palustre. Most plant species characteristic of the P. rotundata bog forest occurred at the burned sites eight years after the fire, but in different abundances. The edificator of the former community—P. rotundata—was mostly absent. Compared with windthrow followed by the bark beetle attack, fire promoted rapid expansion of Molinia caerulea. Soil water in both the undisturbed P. rotundata bog forest and the windthrow – bark beetle affected sites had a similar composition: very low pH values, high P concentrations, low concentrations of cations (Ca2+, Mg2+and K+) and inorganic nitrogen. The concentrations of soluble reactive phosphorus (SRP) and \({\text{NH}}_4^ + - {\text{N}}\) were negatively correlated with the groundwater table. Total P, SRP and \({\text{NH}}_4^ + - {\text{N}}\) concentrations in the soil water at the burned site were by one order of magnitude higher than those in the P. rotundata bog forest, while concentrations of K+, Mg2+ and Ca2+ were only about two times higher. High concentrations of P and N in the soil water found three years after the fire indicated a long-term elevated nutrient content in the soil water.

Mártonfi, Pavol

doi: 10.1007/s12224-008-9004-ypmid: N/A

Abstract New data on the taxonomy, karyology, reproductive biology and secondary metabolites of Hypericum dubium Leers (=H. maculatum subsp. obtusiusculum (Tourlet) Hayek) are given. The neotypification of the name H. dubium by plants from the locus classicus near the town of Herborn in Germany is presented. Hypericum dubium is characterized by stems with slightly conspicuous subsidiary lines, sepals with a finely denticulate or rarely entire apex, petals with pale and black, linear to striiform laminar glands. Karyological data confirm that the taxon is tetraploid (2n = 32). Reproduction by facultative apomixis was discovered using a flow cytometric seed screen. In the spectrum of secondary metabolites, flavonoids, naphtodianthrones and phloroglucinol derivatives were found. The previously described taxon H. carpaticum Mártonfi is reclassified here to the level of nothospecies as H. dubium × H. maculatum. For the epitheton balcanicum a new combination Hypericum ×carinthiacum nothosubsp. balcanicum (N. Robson) Mártonfi is proposed. Finally, this paper provides a revised scheme of relationships among taxa of the H. maculatum group.

Hodálová, Iva;Jr., Pavol Mereďa;Mártonfi, Pavol;Mártonfiová, Lenka;Danihelka, Jiří

doi: 10.1007/s12224-008-9005-xpmid: N/A

Abstract Forty-nine morphological characters were scored or measured on 44 populations (376 individuals) of Viola subsect. Viola from the West Carpathians and adjacent areas (Slovakia, Czech Republic, Austria and Hungary). The presence of six species, namely V. alba (represented by subsp. alba), V. ambigua, V. collina, V. hirta, V. odorata and V. suavis s.l. was revealed based on pollen fertility, cytological and morphometric analyses. The morphological characters traditionally used to delimit taxa within the subsection and those revealed by our study as most reliable are widely discussed. A key for identifying the taxa and most common hybrids of subsection Viola occurring in the West Carpathians is presented. Chromosome counting and flow cytometry were used to determine the ploidy levels of the populations studied. All individuals of V. alba subsp. alba, V. collina, V. hirta and V. odorata were tetraploid, while those of V. ambigua and V. suavis s.l. were octoploid.