Abstract

The current paper is focused on an emblematic medicinal species, Arnica montana, and on identification of the main threats it faces in the northeastern region of Romanian Carpathians. The species was investigated in 30 localities, in various habitats, characterized by different land management types, and different floristic composition of plant communities. The most important threat for A. montana in NE Carpathians was the habitat loss, mainly caused by abandonment of the traditional meadows management and natural succession of vegetation. Accumulated data underline the importance of management measures for A. montana, measures that have controlled and maintained the habitats of montane grasslands over time. The most suitable method of maintaining habitats in a favorable state of conservation could be represented by a combination of mowing and moderate intensity grazing while maintaining a level of fertilization as low as possible. Collection of flower heads for medicinal purposes must be avoided in small size populations.

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In many European countries Arnica montana is decreasing due to intensification or abandonment of traditional extensive land use and thus is considered endangered. In Romania the species is also decreasing due to excessive collecting for pharmaceutical and cosmetic purposes, but it is still relatively common in montane nutrient-poor grasslands and successional vegetation of forest clearings on acidic soil. In this study we analysed habitats and population structure of A. montana in the Romanian NE Carpathians. We asked for differences in population structure between habitat types and how population structure is related to environmental conditions. We investigated population structure and habitat characteristics in 25 populations of A. montana on three 1 m x 1 m-plots each (total of 75 plots). The plot-based assessment of the population structure included the numbers of rosettes (rosette density), flower heads (flower head density), flowering rosettes and flower stems per flowering rosette. From these variables we calculated the proportions of flowering and vegetative rosettes and the number of flower heads per flowering rosette. Habitats were characterised using climatic data (including elevation), land use types (grazing, mowing or abandonment), vegetation types, soil measurements (pH, several nutrient elements, organic matter content) and N supply on basis of plant indicator values. Vegetation types were defined by using hierarchical clustering and linked to phytosociological syntaxa based on diagnostic species. Observed habitat types included Mountain hay meadows, Species-rich Nardus grasslands and Alpine and subalpine heathlands according to the European Habitats Directive. DCA analysis was used for detecting floristic gradients, which were subsequently correlated to environmental conditions. Relationships between rosette density, proportion of vegetative rosettes, flower head density and number of flower heads per flowering rosette and environmental variables were assessed using GLMs. Five syntaxa with A. montana were identified: Festuco rubrae-Agrostietum capillaris nardetosum strictae, Scorzonero roseae-Festucetum nigricantis, Violo declinatae-Nardetum strictae, Cetrario-Vaccinietum gaultherioidis and Campanulo abietinae-Vaccinietum myrtilli. While vegetation composition was mainly correlated with altitude and soil variables such as pH and organic matter content, altitude was an important predictor for the proportion of flowering rosettes of A. montana, which decreased with altitude. Rosette density of A. montana varied between habitat types and was highest in Mountain hay meadows and lowest in plant communities dominated by tall plants with high cover. Organic matter content of the soil was the only important (negative) predictor for the number of flower heads per rosette, while a hump-shaped correlation was found between the density of inflorescences and the soil pH, with a maximum around pH 4.5. Grassland management was also an important factor for rosette density of A. montana, suggesting that maintaining and promoting traditional land use practices will be the most effective measure for the species' conservation.

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