Climate change is contributing to an increased risk of flower damage by late spring frosts. Monitoring flower temperature is critical for the timely start of frost protection systems. However, there are many weak points that complicate the use of this method. The aims of this study were to: i) find the method of air temperature measurement with the best relationship to the surface temperature of plant tissues and ii) quantify the differences between plant tissues surface temperature and ambient temperature during different weather situations. The surface temperature of plant tissues (budding leaves of grapevine, apricot flower, and unripe pear fruit), air temperature and humidity in the radiation shield, wet bulb temperature and air temperature with an unsheltered thermometer were measured at ten-minute intervals in the spring months. The average temperatures obtained by the individual methods as well as the lowest temperatures were determined from each measurement. Differences between air temperatures and plant surface temperatures, including variation ranges, were also determined. An unsheltered thermometer, in which the energy balance corresponds approximately to that of the evaluated plant surfaces, provided the best relationship with plant tissue temperature. The air temperature measured by the standard method (in a Stevenson screen or in the radiation shield) was almost always higher than the temperature of the plant tissue during periods of negative energy balance. The difference between the minimum temperatures was approximately 0.5 °C. Temperatures more than 1.5 °C higher than the actual temperature of plant tissues were measured in extreme cases.
Air temperature and humidity conditions were monitored in Hradec Králové, Czech Republic, by a network of meteorological stations. Meteorological sensors were placed across a representative variety of urban and suburban environments. The data collected over the 2011–2014 period are analysed in this paper. The data from reference standard meteorological stations were used for comparison and modelling purposes. Air temperatures at the points of interest were successfully modelled using regression relationships. The spatial expression of point measurements of air temperatures was provided by GIS methods in combination with CORINE land cover layer, and satellite thermal images were used to evaluate the significance of these methods. The use of standard climate information has low priority for urban planners. The impact of the urban heat island on city residents and visitors was evaluated using the HUMIDEX index, as it is more understandable for urban planners than temperature conditions as such. The aim of this paper is the modification, description and presentation of urban climate evaluation methods that are easily useable for spatial planning purposes. These methods are based on comprehensible, easily available but quality data and results. This unified methodology forms a theoretical basis for better urban planning policies to mitigate the urban heat island effects.
The results were obtained by measurements in 2014 and 2015 in an apple orchard in Starý Lískovec and Těšetice (South Moravia, Czech Republic, Central Europe) into fertile planting of apple trees. The results show that the bark surface temperature during the year slightly differs from the surrounding air temperature. In addition, it is in average a few tenths of a °C higher in the period before the onset of the vegetation and several tenths of a degree lower during vegetation. Causes of these differences appear to be associated with the flow of sap as well as with foliage. Although it can be reasonably assumed that the temperature of the bark surface on the south side will be significantly affected by the global radiation, our measurements did not demonstrate this dependency. It appears that the wind speed had significantly larger influence on the temperature differences in the non-vegetation period as at speeds over 3.5 m s−1, the drop of temperature is so significant that the bark surface is colder than the surrounding air. Comparison of the development of sums of daily and hourly effective temperatures above 10 °C has shown that where daily values do not show significant differences, hourly values differed so prominently that the calculated date of emergence of adult codling moth in the bark surface was approximately one week earlier than with the use of data for air temperatures.
Hana Stŕedová, Tomáš Stŕeda and Jaroslav Rožnovský
Official price of farmland in the Czech Republic is based on land value in different soil and climatic conditions. The paper compares relevant climatic and agroclimatic characteristics used for land appraisement. Characteristics defined in climatic region of estimated pedological ecological unit system for two fifty years period 1901-1950 and 1961-2010 were evaluated. Area of interest includes 53 points distributed within nine broad areas of the Czech Republic. It is evident that the development of climate has an enormous impact on soil fertility. Difference of station average values of air temperature of both fifty years vary from −0.5 to 1.1 ◦ C (mean difference is 0.3 ◦ C) in the case of vegetation period. The shift of precipitation is not so evident as in the case of temperature. The long term change in precipitation distribution within a year is documented by a different shift of annual, vegetation period and non-vegetation period values. Moisture certainty in vegetation period decreases in all cases of broad areas (except one region). All 50year averages of investigated parameters had been changed in 1961-2010 compared to the mean of 1901-1950. This should be taken into account when fixing the official price. Climatic region parameters should be replaced by a more complex “agroclimatological characteristic”, which take into account also the basic pedological and plant characteristics, for example the available water holding capacity.
Hana Stredová, Jaroslav Rožnovský and Tomáš Streda
Predisposition of drought occurrence is based on combined evaluation of above-normal temperatures and below-normal precipitation. According to the weight of the individual categories of extremity, the five degrees of predisposition to drought were determined (degree 1 is the lowest risk, degree 5 is the highest risk). Evaluation of temperature extremity is based on the determination of abnormality in comparison with average value and standard deviation. Individual categories of extremity of precipitation are determined by comparing the individual monthly data with percentile values. Monthly data of homogenized technical series of the Czech Hydrometeorological Institute were evaluated for the years 1961-2010 in two climatologically dry areas (Breclav and Kladno county in the Czech Republic). Fourty-two months were rated risky in Breclav county and fourty-four in Kladno county. The evaluation shows an increase of predisposition to drought, especially after 1990. The highest incidence of degree 5 was recorded in 2001 to 2010 in vegetation season. Subsequently the drought variability as a mean variance of years/season and drought severity as a sum of degree of predisposition to drought of years/season were assessed. A gradual increase of variability and severity from 1961-1970 to 2001-2010 is visible. The lowest values of variability (maximum 2) and severity (maximum 3) in both counties were recorded in winter.
Bronislava Mužíková, Tomáš Stŕeda and Hana Stŕedová
To evaluate soil moisture conditions in spring crops sowing term, data of bare soil surface state were used. Analysis included 32 stations throughout the Czech Republic. Number of days with dry soil surface in each year was compared with the average number of those days in the period 1961-2010 for a given station. The limits of the individual categories were then determined for the period 1961-2010. The individual values of the number of days with dry condition of soil in the early spring period were compared with acquired 10th, 25th, 75th and 90th percentile average (1961-2010). More days with dry soil are usually observed in April than in March. In both months there are 11 days with this condition of soil altogether on average. Dry early spring occurred mainly in 1961, 1968, 1974, 1981, 1990, 2002, 2003, 2007 and 2009. Wet spring occurred in years 1965, 1970, 1980, 2001 and 2006 at almost all stations. There is a significant correlation (p < 0.01) between number of days with dry condition of soil and elevation (r = −0.51, n = 32). Average number of days with dry condition of soil surface in March and April in the period 1961-2010 ranges from 5 to 21 days, which is similar to the median values. Trend analysis did not produce conclusive results, but linear trend of smoothing April data was significantly increased in most localities. The number of days with dry condition of soil in the past decades has no significant upward or downward trend. However four years (2002, 2003, 2007 and 2009) have been evaluated as dry and two years (2001 and 2006) were evaluated as wet. An amount of extreme spring weather increases.
Bronislava Spáčilová, Tomáš Středa and Pavlína Thonnová
Wind erosion risk strongly depends on soil surface conditions. Aridity or dryness of the climate in the Czech Republic is a typical property for Southern Moravia and Central Bohemia. The study aims to map and assess qualitatively the areas vulnerable to wind erosion using available data and intelligible methodology. The evaluation is based on the number of days when at least once a day dry condition of bare soil surface was recorded. Daily data of soil surface state from 70 climatological stations to 500 m altitude from 1981 to 2010 are used. First, soil conditions from 1st March to 30th April and from 1st September to 31st October were evaluated. Evaluation of erosion risk in May is presented separately in the second phase, because only thermophilous crops (late-sowing crops) can be affected in that time. The results show that mainly in the South and Southeast Moravia, there are areas where up to 60 days with dry soil surface in the spring and autumn occurred. Occurrence of such conditions may represent potential risk of wind erosion for arable soils and therefore potential risk for sown crops and loss of fertile soil surface which is irreplaceable for agricultural activities. The results are applicable for preparation of a concept of wind erosion control measures in the threatened regions.
Tomáš Středa, Hana Středová, Filip Chuchma, Josef Kučera and Jaroslav Rožnovský
The occurrence of drought during flowering (usually from the end of May to the beginning of June) is the most hazardous timing in terms of the possible negative impact of agricultural drought on winter wheat, which is the most cultivated crop in the Czech Republic (about 800000 ha). Lack of water, often accompanied by high temperatures, negatively affects the number of grains in the wheat ear and the tissue development of the developing grain, with consequent impacts on yield and quality of product. With the use of a) long-term time series of agrometeorological data (1961–2010), b) long-term phenological time series of winter wheat (1981–2010), and c) soil conditions data (available water capacity of soils of the Czech Republic) for the arable soil, the ratio of actual evapotranspiration and potential evapotranspiration for the period of 1961–2010, used as an indicator of agricultural drought (lack of water) for wheat, was calculated. The innovative aspect of this categorization of the territory of the Czech Republic according to the risk of occurrence of agricultural drought for winter wheat is considering drought from the aspect of the plant, i.e., evaluation based on the actual consumption of water by the vegetation. This is a very sophisticated procedure. Frequently, water content in soils data, presented as an output of some models, do not fully indicate the possible negative impacts on yield generation because the plants themselves are typically not considered. The method used in this study is universally applicable and allows comparisons of regions at the local, regional, and supra-regional levels. For estimation of the development of agronomic drought in the future, the basic water balances in the growing seasons of 1961–2010 and 2071–2100 were compared using a climate scenario. The forecast indicates a significant deterioration of agricultural drought in the region with probable direct impacts on agricultural production.
Soil frost and the depth of freezing are important for the plant development and for the building industry as well. The depth of soil frost is estimated directly by soil frost tube and indirectly from diagrams of soil temperature according to the isotherm of 0 ◦ C (zero-isotherm). The soil temperature measurement is often used for evaluation of freezing depth, because the frost tubes measurement is rarely performed. Measurement by frost tube is done once a day at 7 a.m. and soil temperature in 5, 10, 20, 50 and 100 cm is measured in three observation terms at 7 a.m., 2 p.m. and 9 p.m. Data from agroclimatological station Pohoˇrelice (1971-2000) were used for the evaluation. Three specific real cold periods (1978-1979, 1984-1985 and 1990-1991) and mean frost depth and absolute maximal frost depth for the whole period were evaluated. Course of frost, terms of beginning and the end of frost period and the term of maximum freezing assessed by both methods are almost identical in all real evaluated periods. The results show that the soil frost depth measured by soil frost tube is often higher than that estimated from soil temperature diagrams. It might be caused by graphical processing, as soil temperatures are measured only at five given depths and the depth of zero isotherm is determined by their interpolation. The most significant differences between both methods were observed when evaluating average values for the entire period 1971-2000.
Air and rock surface temperature regime was monitored in Kateˇrinsk´a Cave in Moravian Karst (Czech Republic, South Moravia). Highly accurate temperature sensors with data logger were used for air temperature measurement. Rock surface temperature was monitored by infrared thermometer and infrared thermal camera. Statistical and graphical processing and 2D map were carried out. The rock surface and air temperature increase as the distance from the entrance increases. The highest dynamics of interior air temperature (amplitude 14.3 ◦ C) and the lowest average temperature (4.03 ◦ C) were detected near the entrance. At a distance of 10 m from the entrance the minimum rock surface temperature was -8.74 ◦ C and maximum 8.60 ◦ C. Rock temperature amplitude decreases as the distance from the entrance increases (at the distance of 271-280 m reached the minimum value 1.19 ◦ C). The strongest correlation between internal temperature in remote part of the cave and external temperature was found when external data series shifted 22 days backward. Maximum temperatures in remote part are affected by attendance. Maximum daily amplitude (MDA) in remote parts reached up to 0.69 ◦ C while MDA near the entrance (up to 4.27 ◦ C) is caused by external weather.