Projected changes of warm season (May-September) rainfall events in an ensemble of 30 regional climate model (RCM) simulations are assessed for the Czech Republic. Individual rainfall events are identified using the concept of minimum inter-event time and only heavy events are considered. The changes of rainfall event characteristics are evaluated between the control (1981-2000) and two scenario (2020-2049 and 2070-2099) periods. Despite a consistent decrease in the number of heavy rainfall events, there is a large uncertainty in projected changes in seasonal precipitation total due to heavy events. Most considered characteristics (rainfall event depth, mean rainfall rate, maximum 60-min rainfall intensity and indicators of rainfall event erosivity) are projected to increase and larger increases appear for more extreme values. Only rainfall event duration slightly decreases in the more distant scenario period according to the RCM simulations. As a consequence, the number of less extreme heavy rainfall events as well as the number of long events decreases in majority of the RCM simulations. Changes in most event characteristics (and especially in characteristics related to the rainfall intensity) depend on changes in radiative forcing and temperature for the future periods. Only changes in the number of events and seasonal total due to heavy events depend significantly on altitude.
Productivity of most improved major food crops showed stagnation in the past decades. As human population is projected to reach 9-10 billion by the end of the 21st century, agricultural productivity must be increased to ensure their demands. Photosynthetic capacity is the basic process underlying primary biological productivity in green plants and enhancing it might lead to increasing potential of the crop yields. Several approaches may improve the photosynthetic capacity, including integrated systems management, in order to close wide gaps between actual farmer’s and the optimum obtainable yield. Conventional and molecular genetic improvement to increase leaf net photosynthesis (P N) are viable approaches, which have been recently shown in few crops. Bioengineering the more efficient CC4 into C3 system is another ambitious approach that is currently being applied to the C3 rice crop. Two under-researched, yet old important crops native to the tropic Americas (i.e., the CC4 amaranths and the C3-CC4 intermediate cassava), have shown high potential P N, high productivity, high water use efficiency, and tolerance to heat and drought stresses. These physiological traits make them suitable for future agricultural systems, particularly in a globally warming climate. Work on crop canopy photosynthesis included that on flowering genes, which control formation and decline of the canopy photosynthetic activity, have contributed to the climate change research effort. The plant breeders need to select for higher P N to enhance the yield and crop tolerance to environmental stresses. The plant science instructors, and researchers, for various reasons, need to focus more on tropical species and to use the research, highlighted here, as an example of how to increase their yields., M. A. El-Sharkawy., and Obsahuje seznam literatury
Factors which have a negative impact on mammal populations were reviewed for all 83 native species occurring in Germany today. Forest management affects most species of the mammal fauna as well as of the sub-groups of Red List species and of species for which a special responsibility for their conservation has been determined in Germany. This is because a high proportion of German mammals are forest-dwelling, which means they are exposed to current harmful forestry practices such as selective harvest of ancient trees. The review also highlights population reduction by direct take of individuals (legal, illegal or accidental) and habitat fragmentation as major conservation problems affecting many species. The analysis of negative impact factors underline the importance of ongoing „traditional“ conservation measures. However, the result of climate change and invasive alien species being less important for conservation, as only few species are affected so far in Germany, is doubtful. The impacts of these two factors may be underestimated owing to a general lack of data. To ensure that conservation problems can be identified and appropriate measures are taken, the implementation of a mammal monitoring programme and specific research projects are needed. International cooperation might be helpful to overcome national shortcomings in mammal conservation in Germany and other European countries.
In the frame of the foreseen climate global changes we analysed the physiological responses of Arbutus unedo L. to the variations of carbon dioxide concentration, leaf temperature, and irradiance by measurements of leaf gas exchange and leaf water potential performed both in field and in the laboratory. Stomatal conductance was not affected by increase of leaf temperature. The growth conditions of potted plants likely made stomata more sensitive to the variation of external parameters than naturally growing plants. The interaction between high CO2 concentration and temperature involved important down-regulation mechanisms in the metabolic pathway of the carbon fixation. From an ecological point of view, the ability of A. unedo to adapt to the field stress makes it highly competitive in the Mediterranean plant community. and M. Vitale, F. Manes.
Povrch každé planety, která má atmosféru, je zahříván nejen přímo Sluncem, ale také infračerveným zářením, které je emitováno amosférou a šíří se dolů směrem k povrchu. Na Zemi udržuje tento úkaz, známý jako skleníkový efekt, střední povrchovou teplotu zhruba o 33 K nad hodnotou, kterou by měla bez jeho působení, a tudíž je podstatný pro život na planetě.
Zářivé procesy, které jsou za skleníkový efekt odpovědné, zahrnují především minoritní složky atmosféry, jejichž podíl se může měnit buď přirozenou cestou nebo jako vedlejší důsledek činnosti lidí. Narůstání posledně jmenovaného "příspěvku" určitě podporuje obecný trend globálního ohřívání povrchu Země, i když díky problémům s modelováním složitých zpětnovazebných procesů, např. těch, které zahrnují působení vodních par, ozónu, oblačnosti a oceánů, neni jednoduché přesně předpovídat rychlost očekávaných klimatických změn a jejich lokální průběh.
Tento článek aktualizuje starší referát, v němž autor diskutoval fyzikální procesy uplatňující se při skleníkovém efektu a teoretické i experimentální práce usilující o pochopení vlivu známých i pouze očekávaných změn ve složení atmosféry na klima. V posledních deseti letech došlo k pokroku jak v oblasti získávání dat, tak i v numerických metodách modelování klimatu. Zdá se, že nové výsledky mají tendenci potvrzovat starší předpovědi pokud jde o pravěpodobnost výrazného nárůstu střední povrchové teploty planety v příštích 50-100 letech, téma však nepřestává být kontroverzní., F. W. Taylor ; přeložil Pavel Svoboda., and Obsahuje seznam literatury
Invasions by alien plant species significantly affect biodiversity and ecosystem functioning. Investigations of the soil seed banks of invasive plant species and changes in the composition and structure of resident seed banks following plant invasions can provide valuable insight into the long-term implications of plant invasions. Soil seed banks play a major role as reservoirs of species and genetic diversity and allow for the persistence of a species at a locality, buffering environmental changes that may occur over time. Despite the emerging body of literature on ecological impacts of invasive plants on the diversity of resident communities, the long-term implications of impoverished soil seed banks for vegetation dynamics and ecosystem functioning have only recently begun receiving attention. Evidence has so far indicated that there is a correlation between the invasiveness of a species and the characteristics of its seed bank, and that changes in the seed banks of resident communities associated with plant invasions affect their biotic resistance to primary and secondary invasions. To promote the study of soil seed banks in the context of invasive species, we (i) summarize the functional roles of soil seed banks; (ii) describe how the capacity to form a seed bank may contribute to a species’ invasiveness using data from the flora of the Czech Republic, showing an increasing representation of species capable of forming long-term persistent seed bank from casual to naturalized to invasion stage; (iii) assess the impact of invasive plants on seed banks of resident communities, including the potential creation of conditions that favour secondary invasions by other alien species or native weeds, and long-term implications of such impact; and (iv) describe the potential effects of climate change on the soil seed bank in the context of plant invasions. We conclude with highlighting promising avenues for future research on invaded soil seed banks, and emphasize the importance of this knowledge in the development of control programs and restoration strategies.
The paper presents the results of analysis of temporal and spatial changes of snow water equivalent (SWE) in the mountain basin of the upper Hron River over 40 hydrological years. Spatial distribution of SWE was simulated with the WaSiM model. Measured as well as simulated data indicated despite large temporal variations of SWE, the period since the mid-1980-ties seems to have less snow than the previous decades. Simulations indicated pronounced decrease of SWE in the southern part of the basin. Changes of SWE in the highest mountains were not so pronounced. The analysis of previous decades is considered to be the first step in the assessment of impacts of expected climate changes in the future. and Príspevok je venovaný analýze časových a priestorových zmien vodnej hodnoty snehovej pokrývky v povodí horného Hrona za obdobie 40 rokov (hydrologické roky 1962-2001). Priestorové rozdelenie vodnej hodnoty snehu bolo simulované modelom WaSiM. Napriek veľkej variabilite vodnej hodnoty merané aj simulované údaje ukazujú, že od polovice 80-tych rokov 20. storočia došlo v povodí k poklesu vodnej hodnoty snehu. Výsledky simulácie priestorového rozdelenia vodnej hodnoty poukazujú na výrazný pokles najmä v južnej časti povodia. Zmeny vodnej hodnoty v najvyšších častiach povodia v jeho severnej oblasti neboli také dramatické. Analýza časových a najmä priestorových zmien vodnej hodnoty snehu za posledné dekády je prvým krokom pri odhade dopadu možnej zmeny klímy na budúce zmeny snehovej pokrývky.
In the context of discussed global climate change the emphasis is placed mainly on the adaptability of the water management methodology at present time. Therefore a questionnaire inquiry oriented to the perception of the climate change impact and current state of adaptation strategies implementation was carried out and evaluated. The research was realised among the water management experts in six large transboundary basins: Elbe, Rhine, Guadiana, Amudaria, Orange and Nile. The questionnaire was divided into six parts concerning for example: expected climate change impacts, adaptation measures, drivers for development of adaptation strategy, adaptation barriers etc. Responses were evaluated with rating and the dominant answers and lists of priority were established. Results were evaluated looking for overall conclusions in all or almost all regions, as well as conclusions for each region. The main benefit of the research lies in the evaluation based principally on the opinions of policy makers, stakeholders and water managers in the river basins not on the climate scenarios. The outcomes have proved understanding of the climate change impact issue over all six basins, only the approach to adaptation is partly different. The historical development of water management in the basin influences the perception as well. and V současnosti se v souvislosti s diskutovanou globální změnou klimatu stále zvyšuje důraz na požadavek adaptability metodik uplatňovaných ve vodním hospodářství. Z tohoto důvodu byl v šesti vybraných světových povodích uskutečněn a vyhodnocen dotazníkový průzkum mezi oslovenými experty se zaměřením na chápání důsledků klimatické změny a na zjištění aktuálního stavu implementace adaptačních opatření v povodí. Šlo o povodí Labe, Rýna, Guadiany, Amudarji, Orange a Nilu. Dotazník byl rozdělen do několika sekcí týkající se např. očekávaných dopadů klimatické změny, adaptačních opatření, podnětů pro návrh strategie adaptace, bariér adaptace atd. Dotazníky byly vyhodnocovány pomocí bodování a stanoveny vždy dominantní odpovědi a seznamy priorit. Výsledky byly vyhodnoceny vždy z obecného hlediska i v rámci konkrétního povodí a vzájemně porovnány. Významným přínosem bylo, že průzkum byl založen na závěrech a zkušenostech expertů, nikoli na klimatických scénářích. Ukázalo se, že ve všech povodích bylo dosaženo pochopení problému dopadu klimatické změny, jen přístup k vlastní adaptaci je částečně odlišný. Záleží rovněž na historickém vývoji vodního hospodářství v daném regionu
In central Europe Adalia bipunctata (L.) occurs in two main colour morphs (typical, melanic), and A. decempunctata (L.) occurs in 3 morphs (spotted, chequered, dark). Temporal variation in the relative frequency of morphs was recorded in populations of the Czech Republic where geographic variation in morph frequency is low. Seasonal trends were investigated in samples collected by a light-trap run daily from March to November for 14 years. In A. bipunctata the melanic form was more abundant in autumn than in spring but the difference was not significant. In A. decempunctata morph proportions did not change seasonally. Samples were also collected by sweepnet from stands of many plant species. In both Adalia species the morph proportions did not differ significantly among collections made on different plants. Long-term changes in morph proportions were analysed by pooling annual samples over all host plants. In A. bipunctata, sampled in 15 years between 1971-2004, there was no significant change in proportion of typical (90.1%) and melanic (9.9%) forms. In A. decempunctata, sampled in 12 years between 1976-2004, the proportions of "spotted" (mean over the years 29.4%), "chequered" (42.2%) and "dark" (21.3%) morphs varied between years. There was a trend toward an increasing proportion of the spotted form in the 2000s compared to the 1970s and 1980s.
Atmospheric CO2 concentration continues to rise and is predicted to reach approximately 700 ppm by 2100. Some predictions suggest that the dry season in West Africa could be extended with climate change. This study examined the effects of elevated CO2 concentration and water deficit on growth and photosynthesis of juvenile cacao. Light-saturated photosynthesis (Pmax), quantum efficiency, and intrinsic water-use efficiency increased significantly in response to elevated CO2, as did a range of growth and development responses (e.g. leaf area and leaf number), but the magnitude of the increase was dependent on the water treatment. Stomatal index was significantly greater in the elevated CO2 treatment; an atypical response which may be a reflection of the environment in which cacao evolved. This study shows a positive effect of elevated CO2 on juvenile cacao which may help to alleviate some of the negative impacts of water deficit stress., F. Lahive, P. Hadley, A. J. Daymond., and Obsahuje bibliografii