Soil seed banks were investigated under the canopies of Robinia pseudoacacia and Gleditsia triacanthos trees in ten urban parks of Budapest. Aims of the study were to quantify the effects of tree age (as expressed in diameter at breast height) and the intensity of gardening treatments on the densities of soil seed banks of the investigated tree species. Two soil prisms, of 6 cm deep and 480 cm3 volume each, were cut under the canopies of solitary tree specimens of various age. Soil samples were washed through a sieve of 1.5 mm mesh size for Robinia, and 3 mm mesh size for Gleditsia, then the seeds were hand-sorted from debris. Hardcoatedness of seeds was broken by mechanical scarification, then their viability was tested by germinating them in Petti-dishes at room temperature under natural daylight regime. Average density of soil seed bank was 871 seeds/sqm (n= 17) under black locust specimens, with minimum and maximum densities of 0 and 9312 seeds/sqm, respectively. The median was 156 seeds/sqm. Under the canopies of honey locust specimens the average density was 633 seeds/sqm (n=20), with minimum and maximum values of 0 and 2312 seeds/sqm, respectively, whereas the median was 375 seeds/sqm. According to the results both tree species are able to form considerable amount of seed banks in the soils of urban parks. Neither black locust nor honey locust seed bank densities depended on the age of tree specimens. However, the intensity of park treatments in the surroundings of the trees had a considerable effect on the densities of the soil seed bank under the canopies of the studied species. Soil seed bank was impoverished or absent under trees standing in park sections receiving intensive, regular, professional treatments, whereas high or extreme high seed densities were related to irregularly applied, medium or low intensity park treatments. Our results call the attention to the risk that alien ornamental park trees, having the potential to form large persistent seed bank in the soil, might escape from cultivation thus being naturalized or even becoming an invasive species. Formation of persistent soil seed bank under the canopies of the studied park trees can be controlled by intensive, regular, professional gardening treatments. Beside this, it is also emphasized that the litter collected from the parks (that contains fruits and seeds of the trees) should receive an appropriate treatment. Without appropriate treatment litter deposits (e.g. in the rural surroundings of cities) could support the establishment of populations of the studied species, and these populations could become starting points for further spread of the alien trees.
|Translated title of the contribution||Soil seed banks of robinia pseudoacacia and gleditsia triacanthos in city parks of Budapest, Hungary|
|Number of pages||10|
|Journal||Journal of Landscape Ecology|
|Publication status||Published - Aug 10 2009|
ASJC Scopus subject areas
- Nature and Landscape Conservation