Manganese Biogeochemistry in a Central Czech Republic Catchment

Mn biogeochemistry was studied from 1994 to 2003 in a small forested catchment in the central Czech Republic using the watershed mass balance approach together with measurements of internal stores and fluxes. Mn inputs in bulk deposition were relatively constant during a period of sharply decreasing acidic deposition, suggesting that the Mn source was terrestrial, and not from fossil fuel combustion. Mn inputs in bulk deposition and Mn supplied by weathering each averaged 13 mg m^?2 year^?1 (26 mg m^?2 year^?1 total input), whereas Mn export in streamwater and groundwater averaged 43 mg m^?2 year^?1. Thus an additional Mn source is needed to account for 17 mg m^?2 year^?1. Internal fluxes and pools of Mn were significantly greater than annual inputs and outputs. Throughfall Mn flux was 70 mg m^?2 year^?1, litterfall Mn flux was 103 mg m^?2 year^?1, and Mn net uptake by vegetation was 62 mg m^?2 year^?1. Large pools of labile or potentially labile Mn were present in biomass and surficial soil horizons. Small leakages from these large pools likely supply the additional Mn needed to close the watershed mass balance. This leakage may reflect an adjustment of the ecosystem to recent changes in atmospheric acidity.     

Size of protected areas is the main determinant of species diversity in orchids

Efficient allocation of conservation resources will be achieved only if the priorities for biodiversity conservation – the “hotspots” – are correctly defined. To achieve this we need to pinpoint the main determinants of species diversity. Area, energy available and latitude are thought to be the most important determinants of species richness. Area is clearly the most important, but the relative importance of the other two is uncertain. To test the relative importance of energy available and latitude, data on the species richness of orchids was collected for various countries in the world, the influence of area factored out and the residuals correlated with energy available at these countries and with latitude. This was performed for both total area and that of the protected areas for the 67 countries from five continents, in order to determine which gives a better prediction. We show that – at the large scale considered – area is always very important, latitude is more important than energy available and the size of the protected areas gives a better fit than the total area of the country in most cases. This implies that conservation efforts should be directed to maximizing the size of the protected areas in each country.     

Indoor Aerosol Particle Deposition in an Empty Office

The size- and time-resolved indoor/outdoor aerosol concentration relationships were studied experimentally in an empty office without internal particle sources. Two Scanning Mobility Particle Sizers (SMPS) and an Aerodynamic Particle Sizer (APS) sampled alternately from indoor and outdoor, together covering the size range 3–10,000 nm. The results showed that the indoor aerosol concentration depends mainly on the air exchange and deposition rates, and the outdoor concentration. At higher air exchange rates the indoor aerosol concentration approaches the outdoor one. This was observed for the accumulation mode particles. The size-dependent deposition rates were estimated using a simple aerosol dynamics experiment. It was based on equilibration of the indoor/outdoor concentrations by opening windows and analyzing the concentration decay curves after the windows were closed. For this purpose a simple mass balance model was used. The overall loss rate and the asymptotic value of indoor concentration were found by applying a non-linear least squares method on the time dependence of the indoor concentrations. The air exchange rate was estimated from the overall loss rate and the steady state values of the indoor/outdoor concentration of the accumulation mode particles.     

Identification of Resistance Genes Against Powdery Mildew in Four Accessions of Hordeum Vulgare SSP. Spontaneum

Summary Four newly detected accessions of wild barley (Hordeum vulgare ssp. spontaneum) resistant to powdery mildew caused by Blumeria graminis f. sp. hordei were studied with the aim of finding the number of genes/loci conferring the resistance of individual accessions, the type of inheritance of the genes and their relationships to the Mla locus. F₂ populations after crosses between the winter variety ‘Tiffany’ and four wild barley accessions and use of microsatellite DNA markers were focused on the identification of individual resistance genes/loci by means of their chromosomal locations. In PI466495, one locus conferring powdery mildew resistance was identified in highly significant linkage with the marker Bmac0213. This location is consistent with the known locus Mla on chromosome 1HS. In the other three accessions the resistance was determined by two independent loci. In PI466197, PI466297 and PI466461, one locus was identified on chromosome 1HS and three new loci were revealed on chromosomes 2HS (highly significant linkage with Bmac0134), 7HS (highly significant linkage with Bmag0021) and 7HL (significant linkage with EBmac0755). Our prospective aim is identification of further linked DNA markers and the exact location of the resistance genes on the barley chromosomes.     

Impact of water scarcity on spruce and beech forests

One of the greatest threats posed by ongoing climate change may be regarded the drought caused by changes in precipitation distribution. The aim of presented study was to characterize reactions to dry conditions and conditions without drought stress on gross primary production (GPP) and net ecosystem production (NEP) of spruce and beech forests, as these two species dominate within the European continent. Daily courses of GPP and NEP of these two species were evaluated in relation to an expected decrease in CO2 uptake during dry days. The occurrence of CO2 uptake hysteresis in daily production was also investigated. Our study was performed at Bily Kriz(spruce) and Stitna(beech) mountain forest sites during 2010–2012 period. We applied eddy covariance technique for the estimation of carbon fluxes, vapor pressure deficit and precipitation characteristics together with the SoilClim model for the determination of drought conditions, and the inverse of the Penman–Monteith equation to compute canopy conductance. Significant differences were found in response to reduced water supply for both species. Spruce reacts by closing its stomata before noon and maintaining a reduced photosynthetic activity for the rest of the day, while beech keeps its stomata open as long as possible and slightly reduces photosynthetic activity evenly throughout the entire day. In the spruce forest, we found substantial hysteresis in the light response curve of GPP. In the beech forest, the shape of this curve was different: evening values exceeded morning values.     

Effects of Endo- and Ectomycorrhizal Fungi on Physiological Parameters and Heavy Metals Accumulation of Two Species from the Family Salicaceae

There is increasing interest in poplars and willows due to their biomass production and phytoremediation potential. They host two major types of mycorrhizal fungi that can substantially modulate the physiology of their hosts. In this study, the effects of endo- and ectomycorrhizal fungi on growth, physiological parameters, and heavy metals accumulation were studied in a pot experiment using Salix alba L. and Populus nigra L. The mycorrhizal fungi were inoculated separately and in combination to a soil substrate polluted by a mixture of heavy metals (mainly Cd, Pb, and Zn). Tree species differed in their mycorrhizal affinities, with poplar being colonized predominantly by Glomus intraradices and willow by Hebeloma mesophaeum. H. mesophaeum increased willow height and biomass, while G. intraradices decreased poplar height. The photosynthetic rate remained unchanged, and only minor changes were observed in the relative composition of photosynthetic pigments. Poplar photosynthetic rates and levels of photosynthetic pigments declined, while the epicuticular waxes in leaves increased toward the end of the experiment, irrespective of the inoculation. H. mesophaeum strongly reduced the accumulation of Cd and Fe in willow and poplar shoots, respectively. Our results support the use of selected mycorrhizal strains to tune phytoremediation outcomes in their plant hosts.     

Selective method for cyanobacterial bloom removal: hydraulic jet cavitation experience

The aim of this study was to investigate the suitability of hydraulic jet cavitation as a method for cyanobacterial water-bloom management. Effects of cavitation were studied on laboratory culture of the cyanobacterium Microcystis aeruginosa, on a culture of a green alga Chlorella kessleri (as a non-target species) as well as on a real cyanobacterial biomass with Microcystis sp. as a dominant species. Our results suggested that the cavitation treatment of cyanobacteria is capable of causing the disintegration of their gas vesicles. Using this treatment, up to 99 % removal efficiency of cyanobacteria was achieved. Moreover, no effect on cyanobacterial membrane integrity or metabolic activity was detected by flow cytometry; thus, hydraulic cavitation seems to be harmless from the viewpoint of possible release of cyanotoxins into the water column. The green algae (here C. kessleri) were not affected negatively by the cavitation, and thus, they may still act as the natural nutrient competitors of cyanobacteria in lakes, ponds or reservoirs treated by cavitation.     

Ultraviolet light and semi‐recirculating systems in artificial incubation of noble crayfish (Astacus astacus) eggs: opportunities and limitations

Development of artificial crayfish egg incubation is a milestone in intensive culture of crayfish as commercially important freshwater animals. This study evaluated experimental treatments combining continuous UV lighting, a non‐chemical antifungal treatment, with an initial formaldehyde bath for noble crayfish (Astacus astacus) eggs incubated in semi‐recirculating systems, which requires less than 1 per cent the amount of water necessary for conventional flow‐through systems. The one‐time administration of a pre‐incubation bath to reduce formaldehyde exposure was ineffective. Ultraviolet irradiation of recirculating water provided poor results (13.5% and 35.2% final survival rates to stage 2 juveniles) and led to deteriorating water quality. An inability of hatchlings to successfully moult and the occurrence of limb deformities was observed in UV‐treated groups, and juvenile mortality was found across all experimental treatments.