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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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The dynamics of temperature in birdboxes
Slavíková, Z. ; Žalud, Z. ; Bartošová, Lenka ; Fischer, Milan ; Trnka, Miroslav
The aim of the study was to detect the changing temperature in bird boxes of two bird species-collared flycatcher (Ficedula albicollis, T.) and great tit (Parus major, L.). The work is the result of the monitoring of nesting bird species for two years (2009 and 2010) by temperature sensors. Data was continuously recorded for several different breeding pairs with the micro-datalogers MINIKIN. Temperature sensors were fixed directly into the nest with eggs and also in the upper part of bird boxes or outside the boxes. Temperature data was then processed and analyzed. Experimental work was carried out in a floodplain forest in nature reserve Plačkův les a říčka Šatava near Vranovice, altitude: 170; latitude: 48°56´54´´; longitude: 16°35´50´´. The forest is dominated by full-grown, multi-aged canopy with no forestry management. Experimental site belongs to the same natural biogeocenoses group (i.e. Ulmi-fraxineta carpini) and to the same geobotanical group (i.e. suballiance Ulmenion of the Alnion incanae alliance). Our initial hypothesis assumed that the temperature of eggs in the nest and also the time spent in the bird boxes by both bird species (collared flycatcher and great tit) do not differ significantly. The results showed that during the period when the eggs were layed (by both bird species) the temperature were significantly however the temperature of eggs of collared flycatcher and great tit during the period of incubation were very.
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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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Stomatal conductance of short rotation coppice based on sap flow measurements and its response to chosen meteorological variables
Orság, Matěj ; Trnka, Miroslav ; Fischer, Milan ; Kučera, J. ; Žalud, Zdeněk
The main aim of this study was to derive stomatal conductance (gs) from sap flow measurements and explore some of possible applications of this method. Sap-flow and other meteorological variables were continuously monitored in poplar-based short rotation coppice (SRC) plantation in Bystřice nad Pernštejnem during growing season 2012. Sap flow of 8 trees was measured using heat dissipation method, then expressed as transpiration per square meter of projection area and by adding into rewritten Penman-Monteith equation the canopy conductance (gs) was obtained. Compared with direct measurements on leaf level this approach is advantageous for obtaining gs, because of integrating all leaf categories of tree or whole canopy. Further analysis also proved, that gs is strongly driven by VPD. Finally, it was found that the relationship between gs and VPD is also influenced by available soil moisture content.
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Using remotely sensed NDVI for drought impact assessment within selected crops
Hlavinka, Petr ; Trnka, Miroslav ; Semerádová, Daniela ; Dobrovolný, P. ; Balek, J. ; Možný, M. ; Štěpánek, P. ; Hayes, M. ; Svoboda, M. ; Wardlow, B. ; Žalud, Zdeněk
The relationship between Normalized Difference Vegetation Index (NDVI) and selected agrometeorological parameters (yields of selected crops, water balance) was investigated. The source for NDVI was Spectroradiometer MODIS within satellite Terra and it was available for grids in resolution 500 x 500 m from 2000 to 2010. The analysis was conducted within 12 grids spread through Southern and Central Moravian region. The information about cultivated crops (including spring barley, winter wheat, maize for grains, sugar beet and winter rape) were collected from the farmers and water balance simulated using SoilClim model.
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The responses of two resident and one long-distance migrant bird species to weather conditions in Czech Republic
Bartošová, Lenka ; Trnka, Miroslav ; Bauer, Z. ; Možný, M. ; Štěpánek, P. ; Žalud, Zdeněk
This analyse include three bird species: Sitta europaea L., Parus major L., and Ficedula albicollis T. The data was available for the period from 1961 to 2008 from 3 locations in Czech Republic (centered on 48 48N, 16 46E). S. europaea and P. major are residents, F. albicollis is long-distance migrant species and their phenological development (terms of laying eggs) passed over the different time periods during spring. Phenological phases of birds populations were analyzed and the shifts in the phenophases and also response to climate conditions differed among the bird species.
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Transpiration and biomass increment in short rotation poplar coppice
Orság, Matěj ; Fischer, Milan ; Trnka, Miroslav ; Kučera, J. ; Žalud, Zdeněk
This paper deals with interaction between amount of water lost by tree transpiration and aboveground biomass increment in poplar based short rotation coppice in conditions of CzechMoravian highlands. Stem sap-flow measured on 8 poplar trees by Granier heat dissipation method was put in relation with biomass increments measured both with automated dendrometers so with manual measurements with caliper gauge. Transpiration totals ranged between 28.3–175.6 liters per tree in executed period 3.8.–31.8.2011. Above-ground biomass increments in this period varied between 30.07–519.28 g per tree and mean value of water use efficiency of all monitored trees reached 2.76 g.kg–1. Mean diurnal sap-flow total of all sampled trees was 3.25 liters. Results show that it is possible to establish relationship between transpiration totals and biomass increments (coefficient of determination R2 = 0.90) and also relationship between transpiration totals and stem diameter (R2 = 0.81). These results (especially after obtaining experimental data from spring growth conditions) can be further used for calculations of biomass increments and transpiration as scaling factors from tree level to whole stand level.
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Evapotranspiration of selected agricultural and forest species
Kučera, J. ; Urban, J. ; Trnka, Miroslav ; Fischer, Milan ; Krofta, K. ; Duffková, R.
The aim of this article is a comparison of evapotranspiration (ET) of different covers (turf grass, clover (Trifolium pratense), winter wheat (Triticum aestivum), hops (Humulus lupulus) and the high density poplar stand (J-105, Populus nigra x Populus Maximowiczii)) with the potential evapotranspiration (PET) and the general description the ET rates dynamic during the season. The second goal is to quantify the ratio of the transpiration and the whole evapotranspiration for the two contrasting cultures – the hops and poplars stand. The daily maximal sum of the grass ET reached, similarly like for the other species, up to 5–6 mm per day, which comprises 85–93 % of PET. Significantly higher ET was showed by the culture of clover. On the other hand, the lowest values were performed by the poplar stand in the first year after coppicing. The transpiration to evapotranspiration ratio resulted in 40–70 % by the hops and 80–90 % in case of the poplars.
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Water balance in short rotation poplar coppice and reference grass-plot in conditions of Czech-Moravian Highlands
Orság, Matěj ; Fischer, Milan ; Trnka, Miroslav ; Hlavinka, Petr ; Kučera, J. ; Balek, J. ; Žalud, Zdeněk
This text presents results of a study focusing on differences of water balance between two contrasting cultures - short rotation poplar coppice and grass plot in conditions of Czech-Moravian Highlands. Actual evapotranspiration (by Bowen ratio energy balance method), precipitation and soil moisture in two layers (0 – 0.45 m and 0.45 – 0.90 m) were measured on both plots during seasons 2008 – 2010. The seasonal water lost through evapotranspiration was higher for the grass (560.4 and 508 mm for grass and 523.8 and 351.8 mm for poplar during growing season 2009 and 2010 respectively), but generally the observed amounts of ETa are comparable for both cultures and within the range of values described in literature. Results of soil moisture measurements expressed as soil water availability [mm] were compared with simulations obtained from water balance model SoilClim. The model a little bit underestimated the amount of available water in the system, since based on water balance closure we suggest that there is a higher water income than was recorded from precipitation. This extra water found in observed systems may be supplied probably by lateral underground water inflow from the upper fields.
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