The exotic honey locust (Gleditsia triacanthos) is often planted as ornamental tree in urban parks. In Hungary, it occasionally escapes cultivation, in other countries it has already become invasive, and thus, further spread cannot be ruled out. The production of copious long-lived seeds may contribute to its invasiveness. We investigated the soil seed bank of honey locust growing in urban parks of Budapest (Hungary). Soil samples of 1200 cm 3 were taken under the canopy of 48 solitary female trees, seeds were extracted by washing, and their viability was assessed by germination test following scarification. For each tree, trunk circumference and level of park maintenance were recorded. Seed bank density varied between 0 and 500 seeds/m 2 and in 17 out of 48 cases, it exceeded 100 seeds/m 2. Larger trees tended to form better-developed soil seed bank than smaller ones, yet the level of park maintenance has a much stronger effect: trees in neglected parks produced fivetimes higher density on average than those in perfectly managed parks (126.4 and 24.5 seeds/m 2 , respectively). For a better understanding of the species' invasion risk, detailed seed ecological studies are needed and to prevent its further spreading, a more careful treatment of its litter is recommended.

Examining the urban sprawl around middle-size cities in Hungary and Central Europe the rural change and suburbanization can be characterized by residential out-migration from cities and at the same time by immigration from the rural areas. These processes have intensibed in the former socialist countries after the 2000s and a number of problems have not been addressed, which have become apparent during the eighties and nineties in Western countries. A fast urban sprawl took place with a low level of special control and planning but under the pressure of economic and financial development. The rate of spatial growth often exceeds the rate of population growth, it even occurs in the absence of population growth. In Central European countries, the main destination for migration is the capital cities and their suburbs, therefore suburbanisation studies focus on these areas. However, our aim is to focus on regional centres and their agglomerations, comparing them to capital cities and rural areas. The most dynamic and new urbanisation processes are taking place in urban agglomerations. The phenomena observed in these countries, especially in regional cities, have no historical precedent, but are a novelty from both a social and an economic point of view. The paper concentrates on the urbanisation tendencies of three post-socialist countries – Slovakia, Hungary and Romania –, on the basis of the expansion of the impervious surfaces and the change in the number of the population. In each country the capital cities, the areas of the regional centres, and more remote rural areas are analysed separately. The goal is to examine how much these countries fit into world tendencies, and to see the differences in the density of inhabitants in areas touched differently by urbanisation, among the countries and compared to world tendencies. It is examined in all three countries that have gone through similar economic and political transitions what differences are caused by the diverse historical, geographical and settlement hierarchy endowments at the time of the development and migration boom following the world economic crisis of 2008. It is hard to detect what role the economic crisis played in this, but it is certain that the crisis led to a significant fall, which was followed by a development with quite different directions in the cities, urban fringes and rural areas in the surveyed countries. The flow into cities seems to have accelerated, concerning in the first place capital city regions and the edges of regional centres. Besides population movements, the expansion of built-up areas is much faster than that, especially in less densely populated areas where the dynamism of these was outstandingly high between 2012 and 2018. This may have several negative consequences. In areas in the vicinity of cities zones of such high population density may emerge which may lead to societal problems later.

The goals of this study are the identification of the centres of gravity of the Northern-Transdanubian cities, including Győr, by using a gravitation model and, based on empirical examination, the definition of manpower catchment areas. Then, we are going to analyze the impact fields determined by two methods and seek explanations for the overlaps and differences of the two delineations, which are also going to be analyzed with the consideration of geographic, social and economic factors. Both examinations were carried out at two dates, covering a timeframe of 10 years.