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Long-term productivity of short rotation coppice under decreased soil water availability
Orság, Matěj ; Fischer, Milan ; Tripathi, Abishek ; Žalud, Zdeněk ; Trnka, Miroslav
Wood, in fact, is the unsung hero of the technological revolution that has brought us from a stone and bone culture to our present age (Perlin 1991). Given its high-energy content and versatile use, biomass in the form of wood has been used for energy purposes for millennia. The production and use of woody biomass resources has been expanding around the world. The main drivers of its use as a source of energy are diversification and mitigation of energy related greenhouse gas emissions through partial substitution for fossil fuels. An alternative to sourcing wood biomass from natural forests is short rotation woody coppice. Its productivity is largely dependent on the environment in terms of climatic conditions. Especially drought is the main constraint on woody biomass production and involves serious economic consequences. For that reason, our field experiment was designed to evaluate the impact of decreased soil water availability on productivity of a poplar based short rotation coppice plantation over multiple growing seasons during 2011–2014. Aboveground biomass productivity of treatments with and without throughfall exclusion was assessed within this study. Our results show a systematic decline in the productivity of the plots subjected to decreased soil water availability by 30% in 2011, 20% in 2012, 49% in 2013, and 51% in 2014 compared to control plot. Aboveground biomass productivity ranged from 8.8 to 9.9 t dry matter ha−1 year−1 for the control treatment and 4.5 to 8.0 t dry matter ha−1 year−1 for the treatment with throughfall exclusion.On average, the throughfall exclusion treatment exhibited 47% less productivity than control treatment had over the entire study period.
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Aplikace růstových modelů pro lokální hodnocení dopadů změny klimatu na vybrané plodiny
Hlavinka, Petr ; Trnka, Miroslav ; Balek, Jan ; Dubrovský, Martin ; Pohanková, Eva ; Žalud, Zdeněk
Metodika je zaměřena na přehledný popis problematiky využití specializovaných softwarových nástrojů nazývaných růstové modely s důrazem na jejich aplikaci pro hodnocení dopadů změny klimatu na lokální úrovni. Ambicí této publikace je seznámit čtenáře se stručnou historií vývoje růstových modelů, jejich členěním, aktuálními trendy jejich vývoje a využití, ale v první řadě prezentovat metody přípravy vstupních databází, prvotního nastavení modelů, kalibraci jejich parametrů, přes ověření spolehlivosti prostřednictvím nezávislého vzorku dat (validace), propojení se scénáři očekávaného vývoje klimatu v budoucnu až po hodnocení dopadů změny podmínek na významné polní plodiny a vybrané reprezentativní lokality v České republice.
Plný tet: Metodika_rustove_modely_2015 -  PDF
Plný text: content.csg - PDF
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Analysis of Spring Barley Actual Evapotranspiration
Pozníková, Gabriela ; Fischer, Milan ; Pohanková, Eva ; Žalud, Zdeněk ; Trnka, Miroslav
Evapotranspiration (ET) represents the main water-loss part of the water balance in agricultural landscape. The reliable quantification of the agricultural field ET is, however, still a challenge. To calculate ET, the Bowen ratio/energy balance (BREB) method was used in this study. It is based on measurements of the temperature and humidity gradients and radiation balance with the soil heat flux. Calculated ET was further used to quantify crop coefficient (Kc). Subsequently, we analysed the crop coefficient of spring barley during one growing season since 7th May 2013 to 30th July 2013. We used the data obtained above 1-ha spring barley field in Bystřice nad Pernštejnem, Czech Republic. In particular, we investigated how Kc correlates to climatic conditions as rainfall and soil humidity and how it reflects Plant Area Index (PAI) during the year during different parts of growing season. The cumulative ET of spring barley was 228.6 mm per investigated period. For reference evapotranspiration (ETo) two different approaches were used. Typically, a reference grass cover 0.12 m high standard for Europe. On the other hand, in the USA it is common to use also alfalfa (0.50 m high). ETo of grass was 296.3 mm and ETo of alfalfa was 351.4 mm. Maximum Plant Area Index occurred in June and its value was 4.1. Mean Kc in May was 1.17 for reference grass and 1.03 for alfalfa. Similarly in June, Kc was equal to 1.16 (grass) and 1.03 (alfalfa). Finally in July, for reference grass Kc was 0.55 and 0.48 for alfalfa. The decline at the end of the growing season was caused by dry weather and ripe stage of spring barley.
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Poplar-based short rotation coppice under artificially induced drought stress
Orság, Matěj ; Fischer, Milan ; Trnka, Miroslav ; Žalud, Zdeněk
The main aim of this study was to evaluate the diff erences in chosen microclimatological and ecophysiological variables between two types of experimental plots with diff erent levels of available soil water within a poplar-based (Populus nigra × P. maximowiczii) short rotation coppice plantation (SRC) during summer 2012. Diversity of sap fl ow, stomatal conductance and biomass increment were monitored between two treatments during the growing season of 2012. Th ere are 3 pairs of experimental plots under research. Each pair comprises a control plot and a neighbouring plot, equipped with a roof system, draining 40 % of the incoming rain water away (the water reduced plot). Our results show that a 40 % reduction in through-fall resulted in a 26 % reduction in transpiration and a 27 % reduction in stomatal conductance over the four month study period, which led to a statistically signifi cant (p = 0.03) deceleration of above-ground biomass accumulation at the plots with water-reduced treatment.
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Determination of errors in energy flux estimates using the bowen ratio energy balance method
Pozníková, G. ; Fischer, Milan ; Trnka, Miroslav ; Žalud, Zdeněk
The Bowen ratio energy balance method (BREB) is based on the measurement of air temperature and humidity gradients in at least two vertical levels above the surface of interest. So far, there have been a limited number of studies dealing with the footprint of the BREB. Staying conservative, many authors used the upper sensor of the BREB as a single point to determine the footprint of the BREB. In fact, the footprint of the fl uxes rather should be explained as a source area of the single point measurement carried out somewhere between the two BREB levels. It was suggested that this single point lies close to the geometrical mean of the two aero dynamical heights. However, there has still been no consensus regarding if this apparent height is fi xed or not, and if the second is true, whether it is a function of the Bowen ratio itself. Th e submitted study deals with the footprint of the BREB using several BREB experiments above various covers with diff erent fetches. Moreover, by simulating diff erent Bowen ratios between the area of interest and the contaminating area we attempt to investigate for which conditions (dry or wet) and type of transition (from drier to wetter or vice versa) the method is more sensitive to the limited fetch.
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Phenological response of flood-plain forest ecosystem during 1961-2011
Bartošová, Lenka ; Trnka, Miroslav ; Bauer, Z. ; Štěpánek, P. ; Možný, M. ; Žalud, Zdeněk
The presented study is focused on 50 years of phenological observations (1961–2011) of the herbs, shrubs, trees and bird populations and the phenological phases that create a continuous phenological sequence covering the whole spring aspect of the fl oodplain forest ecosystem. Th e phenological phases were observed for 5 herbs, 5 shrubs, 3 trees and 2 bird species. Th e phenological phases were observed as precisely as possible by only one observer during the whole time of observation. All observed plants and bird species showed statistically signifi cant shift s to the earlier time but the rate of shift ing among the parts of the fl ood-plain forest ecosystem was diff erent. Th e most progressive shift s were detected for herbs (the rate of shift ing was on average 13.9 days), followed by shrubs (phenophases advanced by 11.3 days on average), trees (phenophases advanced by 10.2 days) and fi nally by bird species (phenophases advanced by 9.6 days on average). Consequently the length of overlap of the chosen phenological phases was elaborated. Th e rate of shortening or lengthening of the overlap diff ers among all parts of the ecosystem and indicates not only the separation of phenophases but also no statistically signifi cant change in the length of overlap in each part of the ecosystem.
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Remotely sensed NDVI as a support tool for agricultural drouhgt assessment
Hlavinka, Petr ; Semerádová, Daniela ; Trnka, Miroslav ; Lukas, V. ; Bohovic, R. ; Balek, J. ; Wardlow, B. ; Hayes, M. ; Tseagaye, T. ; Žalud, Zdeněk
Th e main aim of the submitted study was to introduce how the remotely sensed NDVI (Normalized Diff erence Vegetation Index) could be used for agricultural drought assessment within the Czech Republic. Th e relationship between NDVI values and observed yields of spring barley and winter wheat was analyzed for selected districts. Moreover the ability of NDVI (at district level in the form of seasonal greenness – SG) to explain the water balance or drought occurrence and severity was tested. For this purpose a data mining technique was used. A relative form of the Palmer Drought Severity Index (rPDSI) was used as a dependent variable to indicate drought occurrence. A Standardized Precipitation Index (SPI), percentage of average SG (PASG), Start of Season Anomaly (SOSA) and district identifi cation were used as independent variables. MODIS (Moderate Resolution Imaging Spectroradiometer) observations from the Terra satellite were used as a source of NDVI. Th e situation within 6 selected districts (Olomouc, Přerov, Znojmo, Břeclav, Žďár nad Sázavou and Havlíčkův Brod) during the period from 2000 to 2012 was analyzed. Promising results were achieved, so practical use of this approach (e.g. for spatial and temporal assessment of drought stress within the vegetation) could be expected.
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Estimation of above ground woody biomass of SRC hybrid poplar clone J-105 in different fertilizer treatments in Czech-Moravian highland
Tripathi, A.M. ; Trnka, Miroslav ; Fischer, Milan ; Orság, Matěj ; Fajman, M. ; Marek, Michal V. ; Žalud, Zdeněk
Short rotation coppice poplar hybrid clone J-105 (Populus nigra x P. maximowiczii) is studied as an alternative source of bio-energy in the region of Czech-Moravian Highland. The plantation was established in 2001 at the locality Domanínek in the vicinity of Bystřice nad Pernštejnem (Czech Republic, 49o32’N, 16o15’E and altitude 530 m a. s. l.) where mean annual rainfall of 609 mm and mean annual temperature of 7.2oC was recorded between 1981 and 2010. The total area planted with the clone was close to 1.5 ha with total plantation area being close to 3.5 ha. The plantation with planned density of 9,216 trees ha-1was established on the former agricultural land and the length of the rotation cycle was set to 6-8 years. At the beginning of the second rotation period i.e. in spring 2009 (following winter harvest), the plantation was divided into four randomized blocks with different nutrient treatments and three replicates (4×3). These treatments comprised of application of mineral NPK fertilizer (nitrogen 305 kg ha-1, phosphorous 154 kg ha-1 and potassium 291 kg ha-1), sewage sludge (4200 kg/ha-1) and ash (1000kg ha-1) and lime (5 ton ha-1), while control was with natural nutrients content only (deposition and leaves mineralization). The objectives of the study were to estimate the above ground annual yields (based on allometry and stem inventory), the mortality and the shoot to stump ratio as the main productivity characteristics.
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Applicability of Bowen ratio energy balance method in fetch limited conditions
Pozníková, G. ; Trnka, Miroslav ; Fischer, Milan ; Orság, Matěj ; Žalud, Zdeněk
Water plays a key role in the climatic processes of the Earth. In terrestrial ecosystems the main component of water loss is evapotranspiration. One of the standard techniques used to measure evapotranspiration indirectly is the Bowen ratio energy balance method (BREB). This study focuses on the quantification of errors caused by insufficient fetch (upwind distance from the edge of investigated cover) using data from two BREB systems obtained through intensive summer 2012 campaign. The measurement took advantage of one mobile and one fixedly positioned BREB systems employed at turf grass cover from the prevailing north-west wind direction surrounded by broadleaved trees, poplar stoolbed dirty road and buildings at experimental station in Domanínek near Bystřice nad Pernštejnem. Surprisingly, the results showed no significant systematic deviation between the reference BREB with sufficient 180 m long fetch and mobile BREB positioned at fetches between 10 to 100 m. Moreover, it was not found any impact of the fetch on non-systematic errors leading to the conclusion that the fetch did not have any effect on the overall data quality and consistency. One of the explanations may be very similar response to soil moisture conditions of the selected contrasting living ecosystems and thus their similar Bowen ratios.
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Calibration of the selected crop growth models for spring barely
Pohanková, E. ; Trnka, Miroslav ; Hlavinka, Petr ; Takáč, J. ; Kersebaum, Ch. ; Orság, Matěj ; Fischer, Milan ; Pokorný, E. ; Žalud, Zdeněk
The climate change is one of the most discussed global problems. One option how to estimate the effects of expected future climate conditions on plant production is the use of the crop growth models. Our aim was the calibration of two models (Daisy and Hermes) based on observed and measured data that were collected for spring barley (represented by cultivars Tolar and Blaník) at experimental site Bystřice nad Pernštejnem during 2011 and 2012. The onset of flowering was underestimated by an average of 1.1 and 1.6 days and maturity by 5.8 and 9.0 days using Daisy and Hermes respectively. On average Daisy systematically underestimated yields by 0.3 t/ha-1 and Hermes overestimated yields by 1.24 t/ha-1. We expect further improvement of these models estimates using the available result from the following years
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