The greater the proportion of Robinia pseudoacacia in a stand the greater its effect on the population characteristics of Erythronium dens-canis

Management of invasive alien plants is an increasing problem throughout the world. In some cases native rare or protected species can appear or even prefer habitats dominated by invasive alien plants, which raises questions about the optimal treatment of such areas. Erythronium dens-canis in Hungary is a protected species which only have several occurrences in the country and a number of these populations situated in Robinia pseudoacacia stands developed after harvesting native forests. In this study a total of five populations of E. dens-canis were surveyed between 2020 and 2022 in southwestern Hungary examining and comparing the ongoing demographic changes under native and Robinia stands by monitoring individual plants. Two populations were situated in forests composed of native tree species, two in Robinia pseudoacacia-dominated stands and one in a Robinia-native tree species mixed stand. We categorized the plants into five age-state categories: dormant, seedling, juvenile, vegetative adult, and reproductive adult. We found some considerable differences (e.g. leaf size, reproduction rate) between the populations situated in native and in Robinia stands, whereas the population in mixed forest showed intermediate character in most examined factors. Based on our results, R. pseudoacacia have a significant effect on the phenology and life history of E. dens-canis, and this effect is greater with higher proportion of R. pseudoacacia in a forest stand where the E. dens-canis occurs

The greater the proportion of Robinia pseudoacacia in a stand the greater its effect on the population characteristics of Erythronium dens-canis

Management of invasive alien plants is an increasing problem throughout the world. In some cases native rare or protected species can appear or even prefer habitats dominated by invasive alien plants, which raises questions about the optimal treatment of such areas. Erythronium dens-canis in Hungary is a protected species which only have several occurrences in the country and a number of these populations situated in Robinia pseudoacacia stands developed after harvesting native forests. In this study a total of five populations of E. dens-canis were surveyed between 2020 and 2022 in southwestern Hungary examining and comparing the ongoing demographic changes under native and Robinia stands by monitoring individual plants. Two populations were situated in forests composed of native tree species, two in Robinia pseudoacacia-dominated stands and one in a Robinia-native tree species mixed stand. We categorized the plants into five age-state categories: dormant, seedling, juvenile, vegetative adult, and reproductive adult. We found some considerable differences (e.g. leaf size, reproduction rate) between the populations situated in native and in Robinia stands, whereas the population in mixed forest showed intermediate character in most examined factors. Based on our results, R. pseudoacacia have a significant effect on the phenology and life history of E. dens-canis, and this effect is greater with higher proportion of R. pseudoacacia in a forest stand where the E. dens-canis occurs

One year of conservation management is not sufficient for increasing the conservation value of abandoned fen meadows

In Central Europe many grasslands are threatened by the abandonment of traditional land use, leading to litter accumulation and encroachment of competitive grasses, woody and invasive species, ultimately causing the loss of biodiversity in the long run. Resumption of traditional management practices might reverse the negative effects of abandonment, but can be challenging in the current socio- economic context, especially in habitats providing poor-quality forage, such as fen meadows. Given the limited resources of nature conservation agencies, it is crucial to find proper alternative management options to tackle the complex conservation problems these habitats are facing. We studied three sampling sites in an abandoned fen meadow in West Hungary that are subjected to litter accumulation and the encroachment of competitive grasses, shrubs and the invasive giant goldenrod (Solidago gigantea). In a baseline survey in 2019, we evaluated the relationship between the abovementioned threat factors and conservation value indicators (i.e. Shannon diversity, herbaceous species richness, cover of forbs, number of flowering shoots of forbs, naturalness score and forage quality). In a field experiment we used the BACI (Before-After-Control-Impact) design to study the effects of a traditional (mowing) and two alternative (mowing without hay removal, burning) conservation measures and no management (control) on the threat factors and conservation value indicators. We tested the short-term effects of these management types on all dependent variables measured in 2020 by using generalised linear mixed-effect models. In our study system the purple moor-grass (Molinia arundinacea) as dominant species had the most significant negative impact, affecting four out of the six conservation value indicators studied. Litter accumulation had significant negative effects on three indicators. We found that the single application of the tested treatments was not successful in reaching the conservation targets, neither in terms of mitigating the threat factors nor in increasing the conservation value indicators. Mowing and burning treatments both reduced the amount of litter, but the cover of Molinia (the strongest predictor of the conservation value indicators) was unaffected by all treatment types. As a consequence, we did not detect any effects of the treatments on the indicators of conservation value one year after the treatments. It is likely that repeated treatments are necessary to achieve positive changes in conservation value. Another possible explanation is that the applied treatments did not target the most influential threat factor, i.e. the encroachment of Molinia. Therefore, we recommend determining the most influential threat factors first before applying resource-consuming conservation management treatments in grasslands facing multiple threat factors