Germination requirements of the subordinate fen meadow species Valeriana dioica L

Plant species of the intermediate life strategy type are characteristic for species-rich grasslands, which are sensitive to changes in the level of disturbance. Germination and early establishment of seedlings is expected to be the most crucial stage, limiting the successful colonization of appropriate sites. Valeriana dioica is a typical plant of calcareous fens, which are dependent on regular suppression of strong competitors by means of moderate land use. It is endangered in many parts of Central Europe, including Lower Austria. We studied the effects of light, temperature and pre-treatment (cold stratification) on the germination success of V. dioica seeds and the role of litter produced by different competitors on the early establishment of seedlings. We tested seeds from five populations differing in the level of competition for light and considered also the morphological variability of propagules and maternal plants. We found that V. dioica is able to germinate without light. It showed high germination percentages both under high summer temperatures independent of cold stratification and at low temperatures, but only after the stratification. Litter produced by dicotyledonous forbs was less hampering for the seedlings than that of small sedges or grasses. Valeriana dioica possesses a broad regeneration niche and is able to use gaps for germination and establishment both in spring and in summer. It reproduces successfully in herb-dominated fen meadow vegetation but disappears from reed communities. This study demonstrates the significant plasticity of the regeneration niche for a species with an intermediate life strategy and also stresses the importance of gaps for its reproduction.

Hydrological background of the dune slack vegetation in the Kiskunság

Hydrological background of the dune slack vegetation in the Kiskunság In the southern Kiskunság the natural vegetation (sand steppe, fen meadow, fen or marsh and alkali vegetation) survived in the dune slack meadows (DSM). The vegetation of these meadows are species rich, and has high natural value. The main goal of this study is to reveal the hydrological backgrounds in order to help conservation of the natural values. Two DSM was investigated (MM and CS site): vegetation was sampled, observation wells were planted, and data of other wells in similar position were used to describe the hydrological background of the vegetation. The characteristic groundwater level of the same vegetation type in the relatively wet 2005 year was higher in MM site, than in the CS site. We suppose, that this is a consequence of the earlier vegetation change because of the strong decrease of groundwater level in the region of MM site. The model of hydraulic flow system showed that the DSMs are situated in hydraulic discharge zones. We suppose, that an upward flow plays an important role in development of alkali vegetation in the CS site. Cross-correlation coefficient between groundwater and previous precipitation indicated a quick infiltration of rainwater into the soil, and a pressure front of the groundwater stream reaching the area of well after 22-23 days after rainfall. The quick and strong regional hydrological changes, especially the decrease of groundwater level would endanger this valuable vegetation, but certain resistance and plasticity of it is rather possible.