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Predicting light use efficiency using optical vegetation indices at various time scales and environmental conditions
Kováč, Daniel; Ač, Alexander; Veselovská, Petra; Dreveňáková, Petra; Rapantová, Barbora; Klem, Karel
2017 - English
This study presents data points acquired during 2 years of measuring optical properties and gas-exchange\ncharacteristics of European beech (Fagus sylvatica) and Norway spruce (Picea abies) tree species in controlled\nenvironments. The observed statistical relationships between 105 pairs of selected optical parameters\n(i.e. photochemical reflectance index [PRI], ΔPRI, and normalized difference between wavebands R690\nand R630 [where R is a reflectance at a subscripted wavelength]) and light use efficiency (LUE) were considered\nat assumed different canopy leaf area index, changing pigments stoichiometrics, and daily changing\ndynamics of environmental conditions. Our measurements suggested that consistency of the LUE estimation\nusing PRI may be disrupted by acclimation responses of plants that reduce energetic carriers for\nuse in photosynthetic CO2 uptake and the xanthophyll cycle. Also, a changing chlorophylls-to-carotenoids\nratio tends to interrupt the PRI–LUE relationship. ΔPRI showed sensitivity to leaf area index of the measured\ntrees that complicated leaf-level estimation of LUE. The most consistent assessment of LUE was\nachieved using the chlorophyll fluorescence detecting ratio (R690 – R630)/(R690 + R630).
Keywords:
vegetation indices; various time scale; environmental conditions
Available at various institutes of the ASCR
Predicting light use efficiency using optical vegetation indices at various time scales and environmental conditions
This study presents data points acquired during 2 years of measuring optical properties and gas-exchange\ncharacteristics of European beech (Fagus sylvatica) and Norway spruce (Picea abies) tree ...
Application of multispectral remote sensing indices for sensing indices for estimating crop yields at field level
Jurečka, František; Lukas, Vojtěch; Hlavinka, Petr; Semerádová, Daniela; Fischer, Milan; Žalud, Zdeněk; Trnka, Miroslav
2017 - English
Remote sensing can be used for yield estimation prior to harvest and can replace or complement classical\nways of estimating crop yields. This study was undertaken in Polkovice, located in the Czech Republic’s\nHaná region. For 2015 and 2016, two data sets of satellite imagery were used: the Moderate Resolution\nImaging Spectroradiometer and the Landsat 8. Vegetation indices from satellites were compared with crop\nyields at the level of land blocks. Winter wheat and spring barley yield data, representing crops planted\nover the analysed period, were used for the comparison. The results of the index–yield comparison showed\nthat vegetation indices from remote sensing data provide reliable information for yield estimation prior to\nharvest. Indices are also able to evaluate the spatial variability of a crop within the field. The results showed\nthat remote sensing data need to have detailed spatial resolution in order to provide reasonable information\nabout yield at such a detailed level.
Keywords:
remote sensing; crop yield; vegetation
Available at various institutes of the ASCR
Application of multispectral remote sensing indices for sensing indices for estimating crop yields at field level
Remote sensing can be used for yield estimation prior to harvest and can replace or complement classical\nways of estimating crop yields. This study was undertaken in Polkovice, located in the Czech ...
DYNAMICS OF WINTER SEVERITY AND ITS EFFECT ON RECREATION
Zahradníček, Pavel; Rožnovský, J.; Brzezina, J.; Štěpánek, Petr; Farda, Aleš; Chuchma, F.
2017 - English
Air temperature in winter months and colder half-year is an important factor for wide range of human activities, including recreation. As a result of current climate change, average air temperatures increase in winter as well. This, however, does not mean that there are no frosts. Each winter season can be assessed using several parameters. In this paper we used the sum of effective air temperatures below 0 degrees C and- 5 degrees C. Absolute minimum air temperature was used as an indicator of the extremity of a particular period. Space-time analysis has been performed for both parameters. Air temperatures in winter months are to a large extent influenced by the continentality of the climate. In general, the temperatures in Bohemia rise faster compared to Moravia and the absolute lowest minimum air temperatures are observed in the Western parts of the country. Based on a multiparametric analysis of climate characteristics, the coldest winter and colder half-year was in 1963, in contrast, the mildest winter was in 2007.
Keywords:
winter severity; euro-cordex; absolute minimum; effective temperature; recreation
Fulltext is available at external website.
DYNAMICS OF WINTER SEVERITY AND ITS EFFECT ON RECREATION
Air temperature in winter months and colder half-year is an important factor for wide range of human activities, including recreation. As a result of current climate change, average air temperatures ...
Effect of elevated CO2 on morphological and photosynthetic parameters in two understory grass species in Beskydy Mountains
Holub, Petr; Klem, Karel; Urban, Otmar
2017 - English
We transplanted two grass species, Calamagrostis arundinacea and Luzula sylvatica, to the understory of\na 10-year-old experimental mixed forest exposed to ambient (385 μmol CO2 mol–1, AC) and elevated (700\nμmol CO2 mol–1, EC) atmospheric CO2 concentration using a glass dome facility. Effects of EC on plant\nmorphology and photosynthesis were examined after three years of treatment. We tested the hypotheses\nthat shade-tolerant species can profit from EC even at low light conditions and that relatively low accumulation\nof assimilates at such light conditions will not cause CO2-induced down-regulation of photosynthesis.\nWe expected that EC can substitute insufficient light intensities under the tree canopy and lead to both\nhigher biomass production and survival of plants in deep forest understories. The typical shade-tolerant\nspecies L. sylvatica exhibited positive acclimation under EC allowing higher light use efficiency under subsaturating\nlight intensities as compared to plants grown under AC. In contrast, C. arundinacea showed\nhigher stimulation of growth and photosynthetic rates by EC mainly under saturating light intensities at\nthe beginning of the growing season, when the forest leaf area is not fully developed and the open canopy\nallows a greater proportion of incident light to reach the understory. Our data indicate that growth and\nphysiological responses of EC plants in forest understories are species specific, differ from responses of\nsun-exposed plants, and depend on degree of shading.
Keywords:
Effect of elevated CO2; photosynthetic parametrs; Beskydy mountains
Available at various institutes of the ASCR
Effect of elevated CO2 on morphological and photosynthetic parameters in two understory grass species in Beskydy Mountains
We transplanted two grass species, Calamagrostis arundinacea and Luzula sylvatica, to the understory of\na 10-year-old experimental mixed forest exposed to ambient (385 μmol CO2 mol–1, AC) and ...
Towards a combining of remote sensing and in situ evapotranspiration measurements
Fischer, Milan; Jurečka, František; Anderson, M.; Hain, C.; Pozníková, Gabriela; Hlavinka, Petr; Orság, Matěj; Lukas, V.; Žalud, Z.; Trnka, Miroslav
2017 - English
This study provides preliminary results from combining in situ Bowen ratio energy balance (BREB) and\nevapotranspiration (ET) measurements techniques with physically based remote sensing ET estimates determined\nby the Atmosphere-Land Exchange Inverse (ALEXI) model. Evapotranspiration measurements\nand ALEXI estimates were analysed in an agricultural area close to Polkovice, Czech Republic during 2015,\nwhen a drought spell and intensive heatwaves appeared in the country. The BREB system was monitoring a\nwinter wheat (Triticum aestivum L.) field (~26 ha) while the ALEXI pixel (~5 km resolution) covered a wide\nrange of crops, including mainly winter wheat, spring barley, and winter rape. The study results showed that,\nalthough the applied methods work at different spatial scales (field vs. landscape), their combination can provide\nfurther insights into ET at both scales. For instance, such approach can be used to identify whether a specific\necosystem investigated in situ contributes to cooling or warming of the landscape.
Keywords:
remote sensing; evapotranspiration; Bowen ratio energy balance
Available at various institutes of the ASCR
Towards a combining of remote sensing and in situ evapotranspiration measurements
This study provides preliminary results from combining in situ Bowen ratio energy balance (BREB) and\nevapotranspiration (ET) measurements techniques with physically based remote sensing ET estimates ...
Forest regeneration within the treeline ecotone in the Giant Mountains under climate change
Cudlín, Ondřej; Chumanová-Vávrová, Eva; Edwards-Jonášová, Magda; Heřman, Michal; Štěpánek, Petr; Cudlín, Pavel
2017 - English
Natural regeneration of mountain spruce forests began in the Giant Mountains 25 years ago after a reduction\nof severe and long-enduring air pollution. This process has been influenced by climatic change.\nThe aim of our contribution was to present background data for the potential elevational shift of spruce\nregeneration under conditions of climate change. These upslope shifts may also depend on constraints\nsuch as climate extremes, unfavourable soil conditions, absence of ectomycorrhizal symbionts, and lack of\nmicrosites suitable for seedlings. Since 2014, we have studied the main driving factors affecting Norway\nspruce regeneration, and in particular soil conditions, ectomycorrhizal symbionts, ground vegetation cover,\nand forest health, in six transects across the treeline ecotone located on a NW-to-NE transect through\nthe Giant Mountains. Microclimatic measurements showed that the mean difference in growing season\ntemperature between the montane spruce forests and forests at the treeline was −0.54°C. The model\nHADGEM2 predicted that in 20 years the temperature at the treeline will be similar to the current one at\nmontane elevations. The difference in prevailing soil types between the montane spruce forests and forests\nat the current treeline (i.e. podzol vs. ranker type) could be an important factor limiting success of the\nupslope spreading of spruce. Furthermore, areas covered by microsites favourable for natural spruce regeneration,\nespecially spruce litter patches, decaying wood, mosses, and Avenella flexuosa stands, were\nshown to decrease with increasing elevation. It is likely that spruce will move upslope in response to climate\nchange, but the process is likely to be slow or even blocked for some periods, especially by unfavourable\nsoil conditions and climatic extremes.
Keywords:
forest regeneration; Giant mountains; climate change
Available at various institutes of the ASCR
Forest regeneration within the treeline ecotone in the Giant Mountains under climate change
Natural regeneration of mountain spruce forests began in the Giant Mountains 25 years ago after a reduction\nof severe and long-enduring air pollution. This process has been influenced by climatic ...
Approaching dangerous impacts of global climate change
Ač, Alexander
2017 - English
Current global policy efforts are focused on limiting the global rise in mean temperature to well below a 2 K\nwarming compared to the pre-industrial temperature. It is questionable if achieving such goal is still feasible.\nHere, I review published works that suggesting that to keep global warming below or at a 2 K level cannot\nbe considered as safe, as is often assumed. A large body of studies have emerged recently investigating\nthe impacts of global climate change (GCC) at a 1.5 K or 2 K warming. The impacts range from changes in\nthe hydrological cycle, increasing frequency and intensity of extreme weather events, triggering of change\nfeedback processes at various spatio-temporal scales, affecting biological processes from the molecular to\necosystem levels, and to disrupting socio-economic conditions. In this short review, I present the latest scientific\nknowledge regarding some of the most important impacts of GCC on natural ecosystems, humanmade\nsystems, and societies.
Keywords:
global climate change
Available at various institutes of the ASCR
Approaching dangerous impacts of global climate change
Current global policy efforts are focused on limiting the global rise in mean temperature to well below a 2 K\nwarming compared to the pre-industrial temperature. It is questionable if achieving such ...
Seasonal, weekly and diurnal variability of elemental and organic carbon at a rural background site in Central Europe, a four years of measurement
Mbengue, Saliou; Fusek, M.; Schwarz, Jaroslav; Vodička, Petr; Holubová, Adéla; Holoubek, Ivan
2017 - English
Atmospheric organic (OC) and elemental (EC) carbon play an important role in\natmospheric chemistry, climate change and public health. There have been relatively\nfew studies dealing with EC and OC in rural background sites which are less influenced\nby urban and industrial emissions. Nevertheless, measurements at background areas are\nimportant for understanding the transport and transformation characteristics of\nanthropogenic air pollutants, and their effects on various aspects of regional and global\nenvironment changes. This work is one of the rare studies using a semi-continuous\nmeasurement technique to focus on long-term (4 years) measurements of EC and OC at\nregional background site in Europe. It focuses on the factors or phenomena influencing\nboth diurnal and weekly variability of EC and OC concentrations during various seasons\nat rural background area.
Keywords:
elemental; organic carbon; OC/EC ratio; variability; air masses origin; rural background side
Fulltext is available at external website.
Seasonal, weekly and diurnal variability of elemental and organic carbon at a rural background site in Central Europe, a four years of measurement
Atmospheric organic (OC) and elemental (EC) carbon play an important role in\natmospheric chemistry, climate change and public health. There have been relatively\nfew studies dealing with EC and OC in ...
Drought monitor for the Czech Republic-www.intersucho.cz
Trnka, Miroslav; Hlavinka, Petr; Semerádová, Daniela; Balek, Jan; Možný, M.; Štěpánek, Petr; Zahradníček, Pavel; Hayes, M.; Eitzinger, Josef; Žalud, Zdeněk
2016 - English
Because drought and its impacts are among the worst hydrometeorological extremes (including also Central European conditions), the aim of this paper is to describe the core and use of the Integrated drought monitoring system for the Czech Republic. Land-use, information about soil, vegetation characteristics and meteorological data are used as inputs to validated water balance SoilClim model, which is applied for estimates of actual and reference evapotranspiration and water saturation of the soil profile in % or soil moisture content in mm. Moreover the prognosis of expected soil moisture (based on probabilistic analysis) is calculated for next 1, 2, 4 and 8 weeks. Main results are weekly updated in form of drought occurrence maps, which are published in spatial resolution 500 m for whole territory of the Czech Republic and for all its 76 districts separately. Final maps with detail comments are available at drought topic dedicated web page (ANONYM 3 2014).
Keywords:
model; soil moisture; land use; evapotranspiration; drought assessment
Available at various institutes of the ASCR
Drought monitor for the Czech Republic-www.intersucho.cz
Because drought and its impacts are among the worst hydrometeorological extremes (including also Central European conditions), the aim of this paper is to describe the core and use of the Integrated ...
Drought periods in 2014
Zahradníček, Pavel; Trnka, Miroslav; Štěpánek, Petr; Semerádová, Daniela; Farda, Aleš
2016 - English
The first half of year 2014 was characterized by the occurrence of extreme weather. Episode without precipitation were alternated with thunderstorms, temperature were mostly above normal and was occurred first heat wave. The year began with a very mild winter, when amount of snow was only 27% of long term average and in agricultural region South Moravia only about 10%. The winter temperature was more than 2 degrees C higher than normal. March and April were characterized by low sum of precipitation mainly again in South Moravia, both months were about 70% of long term average. March and April temperature were significantly above normal (March about more than about 4 degrees C and April more than 2 degrees C). In contrast May was cold and rainy. In the middle of the month there were persistent rainfall, which caused an increase of river levels and flooding several areas. June was again very dry. These weather conditions led to the strong dry episodes during first half of the year.
Keywords:
data quality-control; model; drought; Czech Republic; year 2014; precipitation; temperature
Available at various institutes of the ASCR
Drought periods in 2014
The first half of year 2014 was characterized by the occurrence of extreme weather. Episode without precipitation were alternated with thunderstorms, temperature were mostly above normal and was ...
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