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Zuzana Hrevuov Michal Hejcman Vilm V. Pavl Josef Hakl Michaela Klaudisov Jií Mrkvi
ka 《Agriculture, ecosystems & environment》2009,130(3-4):123-130
The resilience, the ability of an ecosystem to recover after termination of perturbation, of highly productive Alopecurus grassland was investigated after the cessation of the following long-term fertilizer treatments applied under a two- or three-cut management regime: unfertilized control, PK, N100PK, N200PK, N300PK and N400PK. Annual application rates of pure nutrients per hectare were 0–400 kg for N, 40 kg for P and 100 kg for K. The dynamics of biomass production were measured for 16 years and the effect of former fertilizer treatments on soil chemical properties, biomass chemical properties, plant species composition and species richness were investigated 16 years after the last application of fertilizers. It was concluded that 16 years was not long enough to achieve resilience in plant-available soil P and K concentrations, N/P ratios in the plant biomass or plant species composition, but that it was long enough to achieve resilience in species richness. In the case of biomass production the effect of former fertilizer treatments was apparent in 10 of the 16 seasons investigated, indicating that resilience in biomass production must be evaluated using data from more than 1 vegetation season. The results of the study stress the necessity for long-term research because of high year-to-year variability in biomass production as well as long-term after-effects of fertilizer treatments in alluvial grassland. 相似文献
84.
Wolfgang Priester (1924–2005) was one of Germany’s most versatile and quixotic astrophysicists, reinventing himself successively
as a radio astronomer, space physicist and cosmologist, and making a lasting impact on each field. We focus in this personal
account on his contributions to cosmology, where he will be most remembered for his association with quasars, his promotion
of the idea of a nonsingular “big bounce” at the beginning of the current expansionary phase, and his recognition of the importance
of dark energy (Einstein’s cosmological constant Λ) well before this became the standard paradigm in cosmology.
In memoriam Wolfgang Priester, 22 April 1924 – 9 July 2005 相似文献
85.
Hana Měšťánková Gilles Mailhot Jaromír Jirkovský Josef Krýsa Michèle Bolte 《Environmental Chemistry Letters》2009,7(2):127-132
Photodegradation kinetics of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in photoreactor with immobilized and suspended
TiO2 photocatalyst were studied. The effect of addition of ferric or ferrous perchlorate was investigated. Whatever the concentration
of Fe(III/II) added there is no significant negative effect on the photodegradation rate of pollutants. On the contrary, depending
on speciation and concentration of iron salts, slight or marked acceleration of the photodegradation kinetics was observed.
This positive influence was more pronounced in the case of TiO2 suspensions than for TiO2 layers. Fe(III) was generally more effective than Fe(II). 相似文献
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Josef Cyrys Annette Peters Jens Soentgen H.-Erich Wichmann 《Journal of the Air & Waste Management Association (1995)》2014,64(4):481-487
In many European cities mass concentrations of PM10 (particles less than 10 μm in size) are still exceeding air quality standards as set by the European Commission in 1999. As a consequence, many cities introduced low emission zones (LEZs) to improve air quality and to meet the limit values. In Germany currently 48 LEZs are in operation. By means of dispersion modeling, PM10 concentrations were estimated to decrease up to 10%. Analysis of PM10 levels conducted for Cologne, Berlin, and Munich some time after the LEZs were introduced showed reduction of PM10 mass concentration in the estimated range. The PM10 particle fraction is, however, composed of particles with varying toxicity, of which diesel soot is highly health relevant. An evaluation of air quality data conducted in Berlin showed that in 2010 traffic-related soot concentrations measured along major roads decreased by 52% compared to 2007. Diesel particle emissions in Berlin were reduced in 2012 by 63% compared to a business-as-usual scenario (reference year 2007). A strong reduction of the traffic-related particle fraction of PM2.5 was also reported for Munich. Therefore, it is likely that the effects of LEZs are considerably more significant to human health than was anticipated when only considering the reduction of PM10 mass concentrations.
Implications: The implementation of low emission zones in German cities might result in a reduction of PM10 levels concentrations by up to 10%. However, it is difficult to show a reduction of PM10 annual averages in this order of magnitude as meteorology has a large impact on the year-to-year variation of PM mass concentrations. Monitoring of other PM metrics such as black smoke (BS) or elemental carbon (EC) might be a better strategy for evaluating LEZs effects. The benefit of low emission zones on human health is far greater than is presently visible from routine measurements of PM10. 相似文献
88.
Kurt Kotrschal Josef Hemetsberger John Dittami 《Behavioral ecology and sociobiology》1993,33(5):289-295
Summary To investigate the dynamics of the winter flock patch exploitation, feeding experiments were performed with 140 semi-tame, free-roaming greylag geese (Anser anser). Three different initial densities of barley were offered on a 50-m2 patch: low (1600 grains/m2), intermediate (3300/m2) and high (I 1500/m2). Goose numbers on the patch, peck rates, and frequencies of agonistic encounters and of alert postures were observed by scanning the flock and in focal individuals. At low and intermediate initial food densities, peck rates decreased with food density, whereas at high food density, peck rates decreased only slightly over the feeding bout. Agonistic interactions increased as food decreased. A switch from exploitation to interference competition occurred at a threshold of approximately 900 remaining grains per square meter. With high initial food density, agonistic encounters began to increase gradually after 20–30 min. The same general patterns were observed for frequency of alertness. Family members occupied the patch for the longest time periods. The family female and the offspring fed most intensely. The family gander however, fed significantly less but was more aggressive and vigilant than all other social categories. Solitary geese spent their time on the patch doing little else but feeding and were the first to leave. It seems that high-ranking families and low-ranking singles adopt different competitive strategies, the former being superior interference competitors whereas the latter are forced scramble competitors.This study is dedicated to the memory of Konrad Lorenz
Correspondence to: K. Kotrschal 相似文献
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