The study deals with the analyses of long-term snow measurements performed in the top-parts of the Jizera Mts. The homogenity of the measured data and the relationship between the snow cover parameters and elevation are tested. The main task is to determine the amount of snow sotrage in forest based on the measurements in open areas. It was proved that: i) the relationships can be defined by means of simple linear regression, ii) the resulting equations differ during the winter season depending on snow accumulation and snow melting periods respectively. The results re the first step in the research which will continue with analyses from other sites in Jizera mountains and new established measurements in the selected climatological stations. and Článek se zabývá analýzou sněhoměrných měření prováděných dlouhodobě ve vrcholových partiích Jizerských hor. Testována je homogenita naměřených dat a závislost parametrů sněhové pokrývky na nadmořské výšce. Jádrem práce je však zjišťování vztahů pro výpočet sněhových zásob v lesním prostředí na základě měření z volných prostranství. Bylo prokázáno, že i)tyto převodní vztahy lze odvodit pomocí jednoduché lineární regrese, ii)výsledné rovnice se liší během zimního období - pro období akumulace sněhové pokrývky jsou jiné než pro období tání. Výsledky jsou prvním krokem výzkumu, který bude pokračovat analýzami dalších profilů v Jizerských horách a nově zaváděných měření na souboru vybraných klimatických stanic.
This article draws upon the remarkable diaries of Vojtěch Berger
to offer an original perspective on left-wing politics and the transformative effects of war, occupation, and violence in early twentieth-century Central Europe. Berger, a trained carpenter from southern Bohemia, began writing a diary at the turn of the century when he was a member of the Czechoslovak Social Democratic Party in Vienna. He continued to write as he fought for the Habsburg monarchy during World War I; moved to Prague and joined the Communist Party; endured the Nazi occupation; and questioned the
Communist Party, and his place in it, after liberation in 1945. Berger’s diary speaks to two constituencies that deserve more attention from historians: Czech-speaking veterans of World War I and rank-and-file members of the interwar Communist Party. The article argues that Berger’s politics, while informed by his experiences and framed by party ideologies and structures,
obtained significance through relationships with like-minded “comrades”. Furthermore, the article examines how Berger used his diary to create political self-understanding, to fashion a political self. Each world war, the article concludes, threw this sense of self into disarray. Each world war also spurred Berger to reshape his political self, and with that to reconstitute his political beliefs, his public relationships, and his sense of belonging in the world. and Článek zahrnuje poznámkový aparát pod čarou
Water flow in a single fracture with variable aperture was studied by means of numerical modeling. For this purpose, two numerical models were developed. Computer simulations of water flow rates, fracture contact areas and transmissivities for fractal and nonfractal fractures were performed. Water flow rates were approximated by a trend function. The effect of the grid size upon the stability of results as well as the dependence of the fracture transmissivity on rate of contact area were studied. The achieved results were compared with measured data. and Studie se věnuje proudění podzemní vody v samostatné puklině metodou numerického modelování. K tomu účelu jsme vyvinuli dva numerické modely. Byly provedeny série numerických simulací proudění vody a výpočtu kontaktní plochy a transmisivity pukliny pro obecný typ pukliny. Byly studovány vliv velikosti sítě generované pukliny na stabilitu perkolačních charakteristik a závislost propustnosti pukliny na poměrné velikosti kontaktní plochy. Získané výsledky byly vyhodnocovány ve vztahu ke známým experimentálním datům.
Giant rosettes are ones of the most striking features of the vegetation in the high tropical Andes, with Coespeletia moritziana reaching the highest altitudes up to 4,600 m a.s.l. Different from other giant rosettes, this species grows on rock outcrops with poorly developed soils and where water availability may be limited. Two questions are addressed in this study: How does this species respond in terms of water relations to maintain favorable gas-exchange conditions? Considering that adult plants rely on a water-reserving central pith, how do early stages respond to this environment’s extreme conditions? Water relations and gas-exchange studies were carried out on juveniles, intermediate and adult C. moritziana plants during wet and dry seasons in Páramo de Piedras Blancas at 4,200 m a.s.l. Adult plants maintained higher leaf water potentials (ΨL) during the wet season, however, no differences between stages were found for the dry season. Minimum dry season ΨL were never near the turgor loss point in any of the stages. Juveniles show a more strict stomatal control during the dry season to maintain a favorable water status. Net photosynthesis significantly decreased in intermediate and juvenile stages from wet to dry seasons. Our results suggest that
C. moritziana resists more extreme conditions compared to other Andean giant rosettes., F. Rada, A. Azócar, A. Rojas-Altuve., and Obsahuje bibliografii
In order to address the question of how elevated CO2 concentration (EC) will affect the water relations and leaf anatomy of tropical species, plants of Jatropha gossypifolia L. and Alternanthera crucis (Moq.) Bondingh were grown in five EC open top chambers (677 μmol mol-1) and five ambient CO2 concentration (AC) open top chambers (454 μmol mol-1) with seasonal drought. No effect of EC was found on morning xylem water potential, leaf osmotic potential, and pressure potential of plants of J. gossypifolia. In A. crucis EC caused a significant increase in morning xylem water potential of watered plants, a decrease in osmotic potential, and an increase of 24-79 % in pressure potential of moderately droughted plants. This ameliorated the effects of drought. Stomatal characteristics of both leaf surfaces of J. gossypifolia and A. crucis showed time-dependent, but not [CO2]-dependent changes. In J. gossypifolia the thickness of whole leaf, palisade parenchyma, and spongy parenchyma, and the proportion of whole leaf thickness contributed by these parenchymata decreased significantly in response to EC. In A. crucis EC caused an increase in thickness of whole leaf, bundle sheath, and mesophyll, while the proportion of leaf cross-section comprised by the parenchymata remained unchanged. These effects disappeared with time under treatment, suggesting that acclimation of the leaf anatomy to the chambers and to EC took place in the successive flushes of leaves produced during the experiment. and E. Rengifo, R. Urich, A. Herrera.