Grassland vegetation in urban habitats – testing ecological theories

During the last millennium, urbanization has considerably changed natural ecosystems and formed new artificial habitats. Habitat loss and changes in the abiotic environment are seriously affecting urban biodiversity. We investigated the vegetation composition of three urban habitat types, vacant lots, urban parks, and peri-urban grasslands, which are characterised by species typical to semi-natural grasslands and ruderal assemblages in the city of Debrecen (East-Hungary). We used five spatial replicates of each habitat type and five random plots (5 m × 5 m) in every site for our analyses. We tested the following hypotheses: (1) lower species numbers and Shannon diversity, and a higher proportion of weeds and disturbance-tolerant species are present in the city centre (i.e. urban parks) compared to more peripheral habitats (vacant lots and peri-urban grasslands), (2) the proportion of warm- and nitrogen-demanding species increases, while the proportion of moisture-demanding species decreases in habitats typical to city centres (3) we also tested the increase in cosmopolitan and alien species and the decrease in species of the natural flora in habitats typical to city centres as predicted by the urban homogenisation hypothesis. We found that species composition of urban habitat types is considerably affected by the specific disturbances and site histories associated with the certain habitats. The most urbanised habitats, the urban parks harboured the lowest number of species and the lowest Shannon diversity. The ratio of weeds and disturbance-tolerants was the highest in the city centre likely due to the high-intensity trampling and soil disturbances. Plant species of city centre were more drought-tolerant compared to periurban grasslands, which is likely due to the increased level of drainage. The ratio of nitrogendemanding species was lower in urban parks and peri-urban grasslands than in vacant lots, likely due to the high level of recent soil disturbance in this habitat type. The proportion of alien species was high both in vacant lots and peri-urban grasslands, even though their disturbance regimes differed considerably. The proportion of cosmopolitan species was significantly higher in urban parks compared to vacant lots and peri-urban grasslands. The large proportion of alien and cosmopolitan species together with the continuous human disturbance put native species at a competitive disadvantage, and accordingly the proportion of these species was lowest in the city centre. Even though the studied urban habitat patches did not contribute considerably to the preservation of rare or endangered plant species, they have an essential role in preserving the last remnants of grasslands in intensively used landscapes, and can be a good basis for urban greening projects

Geotechnical rock mass documentation in the Bátaapáti radioactive waste repository

The geologic, geotechnical and rock mechanical background of the area, which includes an underground cavern system, is very complex. Initially, to describe the rock mass properties, the RMR and Q systems were used, while the rock support system was based solely on the Q system. Later, during construction of the repository chambers, the GSI system was also introduced in addition to the above-mentioned rock classification methods. The correlation and usage of these three different rock mass classification systems were investigated.Special methods were used to obtain more accurate tunnel mapping and documentation, which is based on photogrammetry and photo analyzer software.According to the results, the correlation between the RMR and Q values is independent of the rock type; basically, the same equation can be used for all (differences between experimental error). The GSI intervals also closely follows the same trend as the results of the other two methods

Hundred years after the first triaxial test

It was more than hundred years ago, when Theodore von Kármán (born as Tódor Kármán) designed and developed the first triaxial cell for investigation of brittle rocks behavior. His first research was based on Carrara marble and Mutenberg sandstone with varying confining pressures up to 600 MPa, demonstrating changes from brittle stages to ductile behavior in addition to hardening. The target of this paper is to give tribute to his development and work on this topic, having inspired and influenced many people in rock engineering and geophysical sciences, among others. After a short historical overview of this research the published data are recalculated using different empirical failure criteria which are widely used in the rock mechanics and rock engineering practice. For the recalculation and description of Kármán´s triaxial tests the original Hungarian paper was used

Biodiversity potential of burial places: a review on the flora and fauna of cemeteries and churchyards

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