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Aquatic hyphomycetes or Ingoldian fungi are the major decomposers of leaf litter in temperate aquatic ecosystems. Role of leaf litter quality in structuring hyphomycete communities is intensively discussed among hydrobiologists. Therefore, an adequate sampling strategy of the leaf litter is essential in this field. The present paper aims analysing the appropriate sample size of leaf litter with various diversity and evenness combinations taken from streambeds in the temperate deciduous forest zone.Leaf litter in the streambed was sampled at four stream sections of two tributaries of the Morgó stream in the Börzsöny Mts, Hungary. The tributaries differed in water chemistry, altitude and riparian vegetation. To analyse species number-sample size relations, species saturation diagrams were drawn and statistically evaluated.Results showed that: (1) a sample size of 500 leaves sufficiently describes the species composition of leaf litter taken from streambeds in the temperate forest zone, in cases of low diversity forest stands and high diversity forest stands coupled with high evenness; and (2) for forest sites with high diversity coupled with low evenness values a litter sample composed by 800-1000 leaves is advised to investigate to achieve satisfactory estimation of the species composition of leaf litter.The sampling methods described in this paper are proposed for studies where estimation of leaf litter composition is required to understand the available substrate quality for litter decomposing organisms.

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The paper advocates a more extensive use of additive trees in community ecology. When the distance/dissimilarity coefficient is selected carefully, these trees can illuminate structural aspects that are not obvious otherwise. In particular, starting from squared distances based on presence/absence data, the resulting trees approximate relationships in species richness, a feature not available through other graphical techniques. The construction of additive trees is illustrated by three actual examples, representing different circumstances in the analysis of grassland community data.

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Manna ash (Fraxinus ornus L.) is a typical deciduous tree of South European distributioin reaching the northern border of its range in the Carpathian Basin. The correlation between age and basal diameter of this tree was analysed in three ecologically contrasting habitats, as follows. (1) Succesional habitat. Abandonedframland with scattered occurrence of manna ash as a colonisong tree of this area. (2) Austrian pine plantation, where manna ash often forms a spontaneous subordinate tree or shrub layer. (3) Cotino-Quercetum pubescentis, the naturla vegetation on south facing calcareous hillslopes in Hungary, where Quercus pubescenes Willd. and Fraxinus ornus codominate in the low canopy. At each sampling site 21 individuals were selected with an even distribution within circumference categories ranging  from 6cm to 60cm. Circumference measurements were made at the base of the trunk, or cores were taken by a driller. Linear regression analysis was applied to test the correlation between age and diameter.

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The Discrete Element Method (DEM) for describing the action mechanism between soil and sweep tool can be used to perform a detailed analysis of draft force, soil cutting, clod-crushing and loosening by taking into account the tillage speed and the three soil phases. This study describes the simulation of the 3D DEM soil model and a cultivator sweep digitized with a 3D scanner, showing the soil—sweep interaction as a function of implement draft force and implement operating speed.

The suitability of the model is validated by comparing the results of laboratory and simulated shear tests (static validation) with the results of soil bin tests (dynamic validation). The mechanical parameters of the sandy soil used for the soil bin tests were measured using the direct shear box test. Cohesion for the soil model used during simulations was set using the parallel bond contact model, where the determining factors were the Young modulus for particle contact (E c ) and bonding (Ē c ), the Poisson’s ratio (nu), the normal (σ) and shear (τ) bond strength and the radius of the related volume (cylinder). Once the DEM model parameters were set, the draft force values measured during dynamic testing were harmonized using the value for viscous damping (c i ).

The dynamic soil—sweep model was validated using the viscous damping applied based on the simulated and measured draft force values. The validation of the Young modulus to 0.55e6 Pa (K n = 1.73e4 N/m, K s = 8.64e3 N/m) enabled us to set the draft force values of the model for different speeds (0.8–4.1 m/s) with an accuracy of 1–4%.

During the analysis of changes in tillage quality, the developed dynamic soil—sweep model showed a high degree of porosity (48%) due to grubbing in the attenuated speed range (0.5–2.1 m/s), and a decreasing tendency (0.41–0.39%) in the non-damped speed range (2.1–4.1 m/s). After the initial equilibrium state, the ratio of average particle contacts for the given porosity decreased in the attenuated speed range (coord number: 4.8), and a slight decrease was also found above speeds of 2.1 m/s (coord number: 5.2). In the model, clod-crushing was examined based on the ratio of sliding contacts, and we found a continuous increase (sliding fraction: 2–15%) in the speed range used for the simulation (0.8–4.1 m/s).

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A lot of attention is being paid to the understanding of the influence of soil degradation on human life at the beginning of the 21 st century. Among the many types of degradation processes, structural degradation is widespread on huge areas in Europe. For better control, it is needed to get familiar with all the driving forces, the main reasons that lead to soil degradation (Várallyay, 2003; ESB, 2002). In addition to unfavourable natural conditions, inappropriate land use has an important impact on micro-aggregate stability and the rate of tolerance to deformation forces, such as cultivation and erosion.  Rheological measurements provide new quantitative information on particle-particle interaction, the colloidal stability and structure of concentrated suspensions in general. Field samples from loess derived agricultural soils were investigated. In addition to general laboratory analyses (soil organic matter content, CaCO 3 content, CEC), conventional, simple aggregate stability, and water retention measurements and rheology were applied for investigating the micro-aggregate stability of the samples. The evaluation of pseudoplastic flow curves indicated close relationships between the strength and stability of the physical network and the composition of the suspensions. These soil properties have strong, well-defined connection with tolerating cultivation and capability for erosion. 

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Cereal Research Communications
Authors:
P. Reisinger
,
É. Lehoczky
,
J. Mikulás
,
A. Kismányoky
,
P. Burai
,
G. Nador
,
G. Csornai
, and
J. Tamás
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Acta Botanica Hungarica
Authors:
T. Pócs
,
J. G. Graham
,
M. von Konrat
, and
J. Larraín

Enumeration and distributional data of 28 liverworts new to Peru are presented, accompanied by taxonomic annotations, phytogeographical evaluation and illustrations. Remarkable new Peruvian records include the very rare northern Andean endemic Platycaulis renifolia as well as Frullania pearceana, hitherto known only from its type locality in Bolivia. Oil bodies are described for the first time in the genus Platycaulis and male branches are newly observed in Radula yanoella, a species hitherto known only in sterile state.

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Agrokémia és Talajtan
Authors:
Éva Lehoczky
,
M. Kamuti
,
N. Mazsu
,
J. Tamás
,
D. Sáringer-Kenyeres
, and
G. Gólya

Plant nutrition is one of the most important intensification factors of crop production. The utilization of nutrients, however, may be modified by a number of production factors, including weed presence. Thus, the knowledge of occurring weed species, their abundance, nutrient and water uptake is extremely important to establish an appropriate basis for the evaluation of their risks or negative effects on crops. That is why investigations were carried out in a long-term fertilization experiment on the influence of different nutrient supplies (Ø, PK, NK, NPK) on weed flora in maize field.The weed surveys recorded similar diversity on the experimental area: the species of A. artemisiifolia, S. halepense and D. stramonium were dominant, but C. album and C. hybridum were also common. These species and H. annuus were the most abundant weeds.Based on the totalized and average data of all treatments, density followed the same tendency in the experimental years. It was the highest in the PK treated and untreated plots, and significantly exceeded the values of NK fertilized areas. Presumably the better N availability promoted the development of nitrophilic weeds, while the mortality of other small species increased.Winter wheat and maize forecrops had no visible influence on the diversity and the intensity of weediness. On the contrary, there were consistent differences in the density of certain weed species in accordance to the applied nutrients. A. artemisiifolia was present in the largest number in the untreated control and PK fertilized plots. The density of S. halepense and H. annuus was also significantly higher in the control areas. The number of their individuals was smaller in those plots where N containing fertilizers were used. Contrary to them, the density of D. stramonium, C. album and C. hybridum was the highest in the NPK treatments.

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Acta Botanica Hungarica
Authors:
J. Csiky
,
L. Balogh
,
I. Dancza
,
F. Gyulai
,
G. Jakab
,
G. Király
,
É. Lehoczky
,
A. Mesterházy
,
P. Pósa
, and
T. Wirth

As part of the PADAPT project, the authors compiled the invasion biological database of the alien vascular flora of Hungary, which contains the nativeness, residence time, introduc- tion mode and invasion status of 878 alien or cryptogenic taxa. In the absence of adequate evidence, the classification of some species was only possible into uncertain, transitional cat- egories. The definitions of most categories are compatible with several international termi- nologies, but are primarily based on Central European traditions. Of the 560 taxa that have already been naturalised in Hungary, 85 are invasive, and 22 of them are transformer alien vascular plants. Only 5 of these transformers are included in the European list of Invasive Alien Species of Union concern (Ailanthus altissima, Asclepias syriaca, Elodea nuttallii, Heracleum mantegazzianum and H. sosnowskyi), which require uniform preventive interventions and treatments throughout the continent, while the rest of transformers in Hungary (e.g., Robinia pseudoacacia, Fallopia × bohemica and Solidago gigantea) draw attention to the unique, local and/ or regional invasion biological situation of the Pannonian Basin and Central Europe.

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