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Species palatability, life history traits and litter decomposition rate
PÁLKOVÁ, Kateřina
Palatability of 20 meadow plant species was assessed in the slug grazing experiment conducted. Monocots exhibited significantly lower palatability than dicots. Litter decomposition rate was assessed in the field litter-bag test. Linear regression analysis was performed to answer the main question whether species palatability is related to litter decomposition rate and whether it is determined by the carbon or nitrogen content. Phylogenetically independent contrasts were used to eliminate correlated phylogeny effect. Regression trees were used to detect the effect of species traits on species palatability and litter decomposition rate.
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Symptomes of nitrogen excess in soil
Hynšt, Jaroslav ; Šimek, Miloslav
Nitrogen cycling is one of the most important processes on the Earth. Most of N transformations run in soil. Nitrogen usually enters the soil as occasional input in concentrated forms which means that it is often in excess or in deficit. However, deficit and excess of N have different value in different soils and ecosystems. For example, amount of N which causes significant impact on ecosystem of spruce forest is insufficient for the maize field. This suggests, that the amount of N in soil must be evaluated in context of the whole ecosystem. In N-limited ecosystems, most of N is stored in plant biomass and litter characterized by slow transformations. Productivity of ecosystem is low, but N is utilized with high efficiency. On the other hand, in conditions of high availability of N, losses take place. These differences are reflected in content of different fractions of soluble N in soil and different rates of their transformations.
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Retention of nutrients in floodplains
Vymazal, Jan
Nitrogen and phosphorus transformations in floodplains are manifold and very intensive. However, the intensity of the processes depends very much on climatic and geomorphological conditions and also vegetation may play very important role. Probably the most important process responsible for nitrogen removal in floodplains is denitrification which takes place in anoxic/anaerobic soil and litter layers. Substantial removal of nitrogen may also occur via accumulation in the aboveground plant biomass. This process, however, does not remove nitrogen from the system unless the biomass is harvested. The most important process responsible for phosphorus retention in floodplains is sorption on sediment particles deposited during the flood. Removal via plant harvesting may also add to phosphorus removal.
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The effect of fertilization by nitrogen on leaves of free amino acids in plants
Neuberg, M. ; Pavlík, Milan ; Balík, J. ; Kaliszová, R. ; Pavlíková, D.
The effect of different fertilization systems, especially CULTAN (Controlled Uptake Long Term Ammonium Nutrition), on levels of selected amino acids (alanine, glycine, serine, asparagine and glutamine) was investigated in this study. As modeling plant was used maize (Zea mays L.; hybrid Rivaldo) and levels of amino acid were measured by GC-MS. We found significant difference in the levels of certain amino acids. Concentration of alanine and glutamine was higher by treatment with urea ammonium nitrate solution (DAM 390) compared with individuals treated by ammonium nitrate.
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Interakce UV záření s povrchovým nábojem v N2 povrchovém DBD
De Benedictis, S. ; Ambrico, P. F. ; Dilecce, G. ; Šimek, Milan
In this paper we report on space and time resolved spectroscopic measurements on Masuda type surface DBD fed by N2. In our configuration the discharge presents some defects that lead to the formation of some bright spot inside a regular discharge region formed by streamers. We have carried out an optical investigation of both the regular discharge region and the bright spot one with the aim to stress the aspects of photo emission contribution in the dynamics of microdischarge. We have carried out also spectroscopic space and time resolved investigation of discharge emission when UV photons by a pulsed laser interact with the dielectric surface of DBD. There is a similarity between the time evolution of emission from bright spots and that produced by laser photons.
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Intenzita záření a teplota vyhasínajícího stejnosměrného výboje v směsi dusík-kyslík
Krčma, F. ; Mazánková, V. ; Soural, I. ; Šimek, Milan
This contribution focuses on the oxygen influence to the pure nitrogen post-discharge. The DC flowing afterglow in Pyrex tube at discharge current of 150 mA and pressure of 1000 Pa was studied by optical emission spectroscopy at decay times in the range of 3 – 45 ms. Band head intensities of 1st and 2nd positive and 1st negative nitrogen spectral systems were observed as a function of oxygen admixture ( 0-5000 ppm). The nitrogen pink afterglow effect was observed in all cases. Temperature during the afterglow was determined by two different ways. The first one was the direct calculation of the rotational temperature of nitrogen 1st positive 2-0 band using numeric simulation. The second way was the strongly temperature-sensitive ratio of band head intensities originating from 11 and 12 vibrational levels of N2 (B 3g) state because these levels were populated during the afterglow mainly by the atomic nitrogen recombination.
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