Abstract: However food webs have always been considered as a central issue of ecology, their value and usefulness are frequently questioned. In this paper, I overview some causes of this skepticism and discuss in which cases two or more food webs can be compared. I suggest that the comparability of different food webs is a key to possible applications. I show how are two important topics of recent community ecology (keystone species and food web aggregation) related to the comparability problem. Finally, I overview some recent applications of food web research, where comparability can help understanding

Keywords: food web, indirect interaction, aggregation, keystone species, comparability

Abstract: This paper aims to present a review on the natural stand dynamics as recorded in ‘virgin’ and other untreated beech forest reserves in East Central Europe. This information can contribute to defining the reference point for nature-based management of beech forests. Topics covered include: distribution of beech, major beech forest types, growth characteristics, seed production and survival, germination and establishment, growth and mortality patterns during development, regeneration cycles, dead wood and herbaceous vegetation dynamics. Based on the analyses of scientific traditions, strengths and weaknesses of available information, recommendations for future research activities are also formulated

Keywords: Fagus sylvatica, forest dynamics, virgin forest

Abstract: However food webs have always been considered as a central issue of ecology, their value and usefulness are frequently questioned. In this paper, I overview some causes of this skepticism and discuss in which cases two or more food webs can be compared. I suggest that the comparability of different food webs is a key to possible applications. I show how are two important topics of recent community ecology (keystone species and food web aggregation) related to the comparability problem. Finally, I overview some recent applications of food web research, where comparability can help understanding

Keywords: : food web, population dynamical model, activity function, spatio-temporal simulation model, multivariate state-planes

Abstract: The accuracy of a crop model is judged mostly by how precise it is in estimating the production. The preciseness of a crop model is determined on one hand by the authenticity of the algorithms describing the processes of the real world, while on the other hand by the quality of its input data. The goal of this study was to test how sensitive crop models are to errors occurring in the measurement of key weather and soil inputs. The key weather and soil related input data for most crop models are air temperature, solar radiation, precipitation, saturated water content, drained upper limit and wilting point. The level of error in air temperature, radiation, and precipitation measurements were reported to be ±0.2 o C, ±2% and ±3% respectively by the Hungarian Meteorological Service. An other study reported 0.008 cm3 /cm3 level of error in determining the drained upper limit. The question we asked was: ‘To what extent do the yield and biomass change due to this level of inaccuracies in weather and soil inputs?’ The uncertainty caused by the errors of the measured weather elements was found to be 4.7 and 6.9% for the calculated biomass and yield, respectively. The soil parameter errors caused smaller uncertainties in the simulation results. On an average we got 2.3% uncertainty for the biomass and 3.2% uncertainty for the yield. The effect of weather and soil data uncertainties can both strengthen and weaken each other. In certain cases the uncertainty of the simulation could be over 15% due to errors in weather and soil data.

Keywords: crop modelling, error of measurement, uncertainty of simulation

Abstract: Environmental factors significantly influence the development and growth of plants. The main factors are soil and weather conditions. In real world it is not possible to segregate these influences. Using simulation models there are ways to analyse the effects of the changes of soil characteristics or weather elements separately. This way all the soil characteristics and weather elements can be changed one by one or different combinations of them can be used as input series. In this study real Hungarian soil and weather scenarios were used that are significantly different from one another. Maize and wheat – the two main crops of Hungary – as well as field pea were used. Pea is known as a sensitive crop to weather. 4M-simulation package was used as a modelling tool. Our group at RISSAC based on CERES and CROPGRO models has developed it. The results showed that the weather differences caused more significant changes in yields then soil differences though soils could moderate the effects of the extreme weather scenarios. The measure of reactions is meaningfully different depending on the species and cultivars. Analysis of separated effects of soil and weather factors has not only theoretical and methodological importance, but useful for the practice, too. When new plant species or cultivars are introduced in a country the optimal habitats can be found. The optimal structure for crops (where to seed different crops, and what sequence should be applied) and technology for crops (sawing time, fertilizer application and timing, etc.) can be estimated.

Keywords: crop models, soil, weather, plant development and growth

Abstract: A rich collection of Heteroptera extracted with Berlese funnel by Dr. I. Loksa between 1953– 1974 in Hungary, has been examined. Altogether 157 true bug species have been identified. The great majority of them have been found in very low number, there are only 27 species of which more than 10 adult individuals have been found. Some species considered to be rare or very rare in Hungary have been collected in relatively great number (Ceratocombus coleoptratus, Cryptostemma pusillimum, C. waltli, Acalypta carinata, A. platycheila, Loricula ruficeps, Myrmedobia exilis). The three families, which are more or less rich in species and have the highest ratio of extracted species, were Rhyparochromidae, Tingidae and Nabidae. Out of them, the family Rhyparochromidae has been found to be most diverse and most characteristic at the ground-level. Individuals of the families Tingidae, Hebridae and Rhyparochromidae have been found in greatest number. The occurrence of the lace bug Campylosteira orientalis Horváth, 1881 in Hungary has been verified by a voucher specimen. In respect to the environmental changes through the country, parallel changes have been observed in the zoogeographical distribution of the ground-living bugs.

Keywords: Heteroptera, ground-level, Berlese funnel, species composition, zoogeography

Abstract: A rich material of Heteroptera extracted with Berlese funnels by Dr. I. Loksa between 1953– 1974 in Hungary, has been examined. Altogether 157 true bug species have been identified. The ground- living heteropteran assemblages collected in different plant communities, substrata, phytogeographical provinces and seasons have been compared with multivariate methods. Because of the unequal number of samples, the objects have been standardized with stochastic simulation. There are several true bug species, which have been collected in almost all of the plant communities. However, characteristic ground-living heteropteran assemblages have been found in numerous Hungarian plant community types. Leaf litter and debris seem to have characteristic bug assemblages. Some differences have also been recognised between the bug fauna of mosses growing on different surfaces. Most of the species have been found in all of the great phytogeographical provinces of Hungary. Most high-dominance species, which have been collected, can be found at the ground-level almost throughout the year. Specimens of many other species have been collected with Berlese funnels in spring, autumn and/or winter. The diversities of the ground-living heteropteran assemblages of the examined objects have also been compared.

Keywords: Heteroptera, ground-level, Berlese funnel, plant community, substratum

Abstract: : aquatic bugs, semiaquatic bugs, freshwater, community, pattern-analysis,hydrobiology

Keywords: Phytophthora infestans, epidemic disease, environmental conditions

Abstract: The present study was carried out at lake Balaton during 1999 and 2000, collecting Heteroptera species from 44 sampling sites. The different basins and the surrounding streams were compared based on temporal-spatial patterns of bug assemblies. The dominance and constancy values of the present species were used in the analysis. The Szemes Basin shows the least values of diversity and the streams have the greatest values.

Keywords: aquatic bugs, semiaquatic bugs, freshwater, community, pattern-analysis,hydrobiology