The paper summarizes the results of wind velocity measurement in different distances from windbreak in combination with optical porosity (OP) determination in different periods. Experimental data were obtained by direct measurement of wind speed and OP analyses of images of four windbreaks in Southern Moravia (part of Czech Republic). Wind speed at 2 m above the soil surface in a defined distance from windbreak had been measured since 2006. Thirty images of different phenological stages of selected windbreaks from 2006 to 2010 were analyzed. Windward or leeward images were converted into black and white spectrum. All available measurements were used for a map creation. The highest values of OP (up to 50%) are achieved in non-vegetation period. Due to the high OP variability in height of terminal tree branches "OP reduced" was also assessed (just squares to 2/3 height of windbreaks were evaluated). The wind speed reduction on the leeward side relatively strongly correlated with OP value. The highest correlation was found out when the wind speed measurement at 50 m on leeward side was used. The dependence decreases with increasing distance. Full foliage in summer (10% OP) reduces a wind speed about 60% at 50 m and about 30% at 150 m on the leeward. These values for non-foliaged windbreaks decrease to 80 and 90%. Maximum distance of windbreak effect on wind speed reduction was found out by the extrapolation of the curves constructed using the regression equation of wind speed reduction in dependence on OP and different distances from the windbreak. Regardless of OP value, the reduction effect disappears at a distance of 250 m. The quietest zone of evaluated windbreak with an average height of windbreaks 15-18 m was detected in the area about four times the height (4H). The effect of windbreaks decreases with increasing porosity.

Air temperature and humidity conditions were monitored in Hradec Králové, Czech Republic, by

ABSTRACT:The submitted work deals with the relation between the sum of active temperatures above 7°C and important phenological phases in peach tree cultivation. The aim of the paper is to provide information for growers, especially regarding anticipated harvest dates, which is important for marketing. Data has been compiled for the period 1998-2007 for the variety Catherine, grown in the locality of Velké Bílovice in the Czech Republic. A relationship between the sum of active temperatures above 7°C from the beginning of the year up to the start of blossoming has been identified, and a model determining the harvest date on the basis of the sum of active temperatures in the periods of 30 days and 60 days after blossoming has been tested. conditions. We can also assume that an increase in weather variability, as it is suggested in some studies concerning climate change, will lead to an increase in variation in the start of individual phenophases.The goals of this study were as follows: to test the possibility of using the sum of effective hourly temperatures for a model of the onset of peach tree phenophases and to predict the date of harvest for the selected cultivar. MATERIAL AND METHODSIn assessing the relationship between meteorological factors and the start of phenophases in peaches, we have used average hourly air temperatures. The compiled phenological observations refer to the variety Catherine (synonym Frederika-Catharina, Čepička et al. 1999) in Velké Bílovice, where air temperatures were precisely recorded at fifteenminute intervals with the aid of a HOBO recorder (see e.g. Litschmann 1999) placed close to the observed orchard. The study period comprised the years 1998-2007.We focused on the assessment of the start of blossoming and the start of harvest; these dates were carefully recorded every year. Blossoming was determined as stage F by Baggiolini (1952) (or 65 by BBCH, i.e. at least 50% of flowers open, first petals falling). The beginning of harvest was determined as the period when most fruits reached the optimum market maturity.From the meteorological data, we calculated the sum of active hourly temperatures above the base of 7°C (SAT7), starting from 1 st January every year. In the published literature this index is referred to as GDH (Growing Degree Hours); though, Peréz-Pastor et al. (2004) used it with a base of 6°C. DeJong (2005) used a combination of two cosine curves to calculate GDH, as follows: t ≤ 25: GDH = 10.5 (1 + cos (3.14 + 3.14 (t -4)/(25 -4))) t > 25: GDH = 21 (1 + cos (3.14/2 + 3.14/2 (t -25)/(36 -25))) where: t -temperature (°C).We tried to use this method in our own study, but we failed to reach more exact results. The retarding influence of higher temperatures on phenological development is probably not so critical under the conditions of South Moravia, where the relatively cooler climate prevails. RESULTS AND DISCUSSION Start dates of individual phenophases and temperature characteristics in individual yearsThe average blossoming start date (period 1994 to 2007) of the se...

Urban environment differs from the surrounding landscape in terms of the values of meteorological parameters. This is often referred to as the urban heat island (UHI), which in simple terms means higher air temperatures in cities. The cause of these changes lies in the different active surfaces in cities, which subsequently results in a different radiation balance. The higher temperatures, however, also affect the living conditions in the city and during very high temperature periods can have negative effects on the health of the city inhabitants. The results presented in this paper are based on measurements taken over several years at locations near Hradec Králové, which is surrounded by different surface areas. Environment analysis was performed using the Humidex index. The obtained results show that replacing green areas with built-up areas affects temperatures in the city, when air temperatures are very high they significantly increase the discomfort of the inhabitants. Differences in the frequency of discomfort levels are observed especially during periods of high temperatures, at lower temperatures these differences are not significant. Higher frequencies of discomfort are observed at locations with artificial surfaces (asphalt, cobblestones, concrete) and in closed spaces. In contrast, locations with lots of green areas almost always have the value of this index lower or more balanced. The results should therefore be a valid argument for maintaining and extending green areas in cities.

Lampartová I., Schneider J., Vyskot I., Rajnoch M., Litschmann T.: Impact of protective shelterbelt microclimate characteristics. Ekológia (Bratislava), Vol. 34, No. 2, p. 101-110, 2015.Evaluation of microclimate characteristics of a protective shelterbelt in Obelisk enclosure in 2010. Vegetation performs indispensable functions in the landscape. Protective shelterbelts are important landscape elements. Individual interventions to these ecosystems should be made with the intention to increase the retention capacity of the landscape, the biodiversity, and the stability of individual landscape elements and the landscape as a whole. This article presents the results of the measuring of the effect of model forest vegetation in the proximity of Obelisk in the Lednice-Valtice area on the microclimate. The protective shelterbelt, declared as a forest stand, is located in the cadastral area of Lednice, Podivín and Rakvice. A set of weather stations, supplied by AMETLitschmann and Suchý Velké Bílovice, was used for the measuring. The stations measured wind velocity (m/s), soil temperature in depths of 5 and 10 cm (°C), air temperature (°C), radiation (W.m -2 ) and precipitation (mm) from January 1 to December 31, 2010. The ImageTool application was used to establish optical porosity, based on photos taken in summer and winter. Optical porosity was established as a ratio of white spots to their total number in a specific section of a photograph. The optical porosity was 5% during the growing season and 23% outside the growing season. These values significantly differ from the optimum values for efficient semi-permeable PS, whose porosity is set to 40-50%.