National Repository of Grey Literature 9 records found  Search took 0.01 seconds. 
Response of Soil Respiration, Temperature and Moisture to the Harvest of a Sessile Oak Forest\n
Dařenová, Eva
Forest management, particularly thinning and harvesting measures, has a significant impact on the forest carbon balance. In this study, we investigated the effect of the harvest of a sessile oak forest on soil respiration as a main source of CO2 emissions in forest ecosystems. Soil respiration, temperature and moisture were measured during the two growing seasons, one before and one after the harvest applied on six out of nine studied plots in April 2018. The harvest increased soil temperature by up to 6 °C. Soil moisture did not differ between the plots in 2017, but it was higher in the harvested plots compared to the control in 2018. In the first half of the growing season 2018, the difference between the control and harvested plots ranged between 5 and 100 % in proportion while in the second half the differences decreased only up to 5%. Soil respiration ranged between 1.2 and 3.3 µmol CO2 m-2s-1 during 2017 with no difference between the following variants. In 2018, soil respiration ranged between 1.2 and 7.0 µmol CO2 m-2s-1 and it tended to be higher in the harvested plots compared to the control. The exception was observed shortly after heavy rainfall on 5th September when soil respiration in the control significantly exceeded that in the harvested plots.
Soil Respiration of the Spruce Forest during Four Years after the Application of the Different Dolomitic Limestone Dosage
Rosíková, J. ; Dařenová, Eva ; Kučera, A.
The study focuses on an in situ response of soil respiration at 10 °C (R10) of the Norway spruce monoculture to the application of the different dolomitic limestone dosages (0, 2, 3, 4, 6, 9 a 26 t.ha-1) over a period of four years. Soil respiration was measured within the growing seasons 2016 – 2019. Moreover, the pH was determined in the H and Ah horizons during each season. The effect of liming on soil respiration was statistically significant during all the seasons except for 2017. The greatest effect was observed within the first season after liming. In May 2016, R10 in the limed plots increased as much as by 97% compared to the non-limed ones. However, soil respiration did not increase in the direct proportion to the liming intensity. We found out the correlation between soil respiration and the micrometeorological parameters (temperature and moisture) when both low temperature moisture limited soil respiration. Due to the strong soil buffering capacity, the small effect of liming on the soil acidity was observed in the first study season. In the following seasons, the differences in the pH among the plots with the different liming intensity started to increase, which was, however, observed only in the H horizon. The substantial increase in the soil microbial activity accompanied with faster respiration after liming can lead to the increased threat of rapid mineralization and the loss of soil organic matter with all its negative impacts
Measurement of the vertical profile of the ground level of the atmosphere using an unmanned platform First results
Novotný, J. ; Bystrický, R. ; Dejinal, K. ; Trusina, Jan ; Komínková, Kateřina
Application of new technologies such as unmanned platforms is also on the rise in meteorology. The paper brings the first comparison of measurement sensors placed on the drone with standard meteorological measure-ments on the mast. The mast data provides continuous data over time, but not in space and only in five defined heights. The first results show a good match between mast measurements and measurements using a flying dron in wind direction and wind speed. Additional influences specific to the newly designed measurement method is the main problem, which must be solved.
Changes of microclimate in a sedge-grass marsh within the last 40 years
Dušek, Jiří ; Stellner, Stanislav ; Hudecová, S.
The average, maximum and minimum air temperatures have been gradually increasing since 1977 to 2017. The air temperature rise was not the same in all periods of the year. We found different increases for individual months. The daily mean air temperature rose significantly in the growing period (April-August). The precipitation characteristics have been changing in the sedge-grass marsh too. The observed trends differ among months in sign as well as in the magnitude, and they are consistent with the air temperature changes. We found that extreme precipitation seems to occur significantly more frequently in recent years compared to the period before 2000. Awareness of these changes is important for possible positive human intervention when a desirable wetland ekosystem function is threatened.\n
Utilization of sampling filters from the Kresin atmospheric station for further analysis
Vítková, Gabriela ; Kahoun, D. ; Strnadová, G. ; Hanuš, Vlastimil ; Petrov, M. ; Tříska, Jan ; Holoubek, Ivan
The Kresin At Pacov Atmospheric Station serves as a monitoring point for the occurrence and remote transmission of greenhouse gases, selected atmospheric pollutants and basic meteorological characteristics. The determination of the GHG concentration (CO2, CH4, N2O, CO) is carried out in air continuously sampled at 10, 50, 125 and 250 m heights. The analysis itself takes place at the foot of a high mast where the air is drawn through the tubes of Synflex 1300. lines and individual analyzers are protected from mechanical pollution by input filters that are changed at regular intervals as part of the routine maintenance of the device or earlier when unexpected clogging occurs. Analyzing these filters can provide additional information about the surrounding area. These are stainless filters (Swagelog „T“ filter) with a porosity of 40 μm. A sampling head is provided in front of them to protect them from rough dirt and water drops. The volume flow of the scrubbed air is about 15 l / min, the exchange interval is usually 3 months. The need to replace these filters has increased in recent months as the flow rate on the sampling lines has fallen. The question arises as to how long the filters remain fully passable and how well they serve their purpose without burdening the sampling system and lowering the measurement quality. The results of analyzes of polycyclic aromatic hydrocarbons (PAHs) carried out on filters at the Institute of Chemistry and Biochemistry of the Faculty of Science of South Bohemian University as well as images from the Scanning Electron Microscope (SEM) could be helpful in answering this question. On the basis of the preliminary results, we propose a more extensive study for the use of this waste material for the analysis of solid particles from the atmosphere in the surroundings of AS Křešín near Pacov and the optimization of the QA / QC sampling systems of greenhouse gas analyzers.
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
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).
Influence of the chlorophylls-to-carotenoids ratio on light use efficiency estimation by optical parameters
Ač, Alexander ; Kováč, Daniel ; Veselovská, Petra ; Večeřová, Kristýna ; Klem, Karel
The influence is examined of changing leaf photosynthetic pigments concentrations on sensitivity of the\nphotochemical reflectance index (PRI) and ΔPRI optical parameters in relation to light use efficiency\n(LUE). Photosynthetic and leaf chlorophylls-to-carotenoids (Chl/Car) ratio changes during the growth of\nEuropean Beech (Fagus sylvatica) and Norway spruce (Picea abies) saplings were induced by altering the\nliving environment inside growth chambers. Point reflectance measurements of each individual tree were\nrecording changes in optical properties while measurements were being taken simultaneously of altering\nphotosynthesis. Based on the evaluation of 45 pairs of measurements conducted on six individual saplings,\nthe observed variability in the strength of the PRI and ΔPRI versus LUE relationships was compared to the\nresulting leaf Chl/Car ratio of each tree. Data were used to explain the influence of changing pigments on\nthe sensitivity of each individual optical parameter with regards to the LUE estimation.
Comparison of leaf area index dynamics and radiation use efficiency of C3 crops in the Czech Republic
Tripathi, Abishek ; Pohanková, Eva ; Trnka, Miroslav ; Klem, Karel
Leaf area index (LAI) and radiation use efficiency (RUE) are key parameters for plant growth and productivity.\nBecause of irregularities in weather conditions, accurate estimation of crop production requires\nunderstanding relationships between weather, LAI, RUE, and final production. It is thus important to\nstudy how the LAI dynamics, leaf area duration (LAD), and RUE are related to aboveground biomass production\nfor different crops. In our study, we compared aboveground dry mass production, LAI dynamics,\nRUE, and LAD in three C3 crops (spring barley [SB], winter wheat [WW], and oilseed rape [OSR]) in the\nCzech Republic. LAI was measured on the basis of transmitted photosynthetically active radiation, LAD\nwas calculated by counting the number of days in the growing season, RUE was measured using Beer’s\nlaw, and the aboveground dry mass was estimated at the time of harvest. Results of our study showed high\nbiomass production and RUE in SB while there was highest maximum LAI (LAImax) and LAD in OSR. We\nconcluded that LAI dynamics or LAImax do not fully reflect the crop production and that RUE may be considered\nas a better indicator for aboveground dry mass production.
Use of the ceilometer data to explainig changes in pollutants concetration gradient in the air during the day
Komínková, Kateřina ; Holoubek, Ivan
For the interpretation of air pollutants concentrations, the one of the key parameter is the atmospheric boundary layer (ABL) evolution during a day and night. The ABL is a broad concept that includes different states of airflow dynamics in the part of troposphere closest to the Earth's surface (0-2 km above the surface), which has an effect in this area. A lot of air flow changes occur in the ABL during the day. For the measurement of substances concentrations in the air the development of mixing layer (ML) in the light part of the day is very important. A lot of ground remote sensing methods was developed for determination of ABL height during the day, one of them which can be very simply operated is to use data from ceilometer. However, the obtained outputs cannot be directly interpreted. In addition, in the case of the terrain measurements a lot of cases when ABL height values cannot be determined because the ceilometer measurement is disturbed can occur.\n\n

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