Sonja Škornik

Dry calcareous grasslands from two neighboring biogeographic regions: relationship between plant traits and rarity

European dry grasslands formed of the Festuco-Brometea type are among the most diverse plant communities within agricultural landscapes. We examined floristic composition, functional trait structure and threatened species occurrence in grasslands of this type from in two distinct biogeographic regions, Dinaric (NW Balkan) and the Central European. In the Central European region this type of grassland is threatened by a decline in traditional extensive management. We tested, if differences in the level of threat between regions are matched by differences in community-weighted means for resource use strategy traits and occurrence of Red List (threatened) species. We then tested if threatened species differed in their traits from other species and if threatened species richness was related to CWM for resource use strategy traits. The communities from the Central European region had significantly higher SLA and lower LDMC, which perhaps reflects an increase in intensive agriculture promoting fast-growing species. Threatened species occurrence did not differ significantly between regions, but threatened species richness was significantly negatively correlated with CWM for height and SLA. This may suggest that threatened species are less likely to occur in high productivity communities where light competition is intense. This study provides initial evidence that changes in CWM for resource use strategy traits may provide a useful means for predicting threatened species loss in dry grassland ecosystems.

Grassland succession is mediated by umbelliferous colonizers showing allelopathic potential

Abstract Two Umbelliferous tall herbs – Laserpitium siler and Grafia golaka tend to form monodominant stands in the montane belt of the North Adriatic Karst after grassland abandonment. The germination and development of shade-tolerant species of further successional stages could be facilitated by favorable climatic conditions, measured in the canopy, but colonization by woody species was not perceived, except for Pinus sylvestris and Pinus nigra, which are not common trees in the area. The vegetation history of the site shows rather slow reforestation after abandonment and almost exclusively with pine woodland. All organs of both Umbelliferous species showed high allelopathic potential, measured as significantly inhibited germination and early development of test plants in bioassays. Under similar treatments, the germination rate of P. sylvestris was reduced, but further development of seedlings was stable. One possible explanation for the relative persistence of Umbelliferous monodominant stands is the strong allelopathic potential of both umbellifers. They act as “succession retardants”, and only pinus is able to colonize these stands successfully; the explanation for that is based on the presence of the same essential oils (limonene, pinene) in both Pinus and L. siler.

Assessing community assembly along a successional gradient in the North Adriatic Karst with functional and phylogenetic distances.

Recently, two approaches to account for ecological differences in community composition have been developed: one based on trait differences (functional diversity) and another based on evolutionary history (phylogenetic diversity). Combining them allows an integrated view of processes structuring communities. The North Adriatic Karst is covered by species-rich grasslands, but land abandonment has resulted in replacement by woodlands. This creates a successional gradient along which environmental conditions may change, and different community assembly rules may apply. We sampled 56 plant communities in the Karst and used functional-phylogenetic distances to assess assembly along a successional gradient, from grasslands to shrublands and woodlands. We found 146 species, for which we measured functional traits and built a phylogenetic tree. The three successional stages were floristically different, with grasslands having species that are typical of harsher soil conditions and woodlands with species preferring milder soil conditions. All communities had higher functional than phylogenetic distances, implying that closely related species tended to be phenotypically dissimilar. When more importance was given to functional distances, most grasslands and some shrublands were underdispersed; when more importance was given to phylogenetic distances, only one grassland was underdispersed and one woodland was overdispersed. Combining functional and phylogenetic distances provided us with better estimates of ecological differences in a successional gradient, where environmental filters seem to be the dominant force in early stages and competitive exclusion becomes more important in later stages. Taking into account that sucessional stages are assembled by different rules is essential to predicting their behaviour under future environmental scenarios.

Phylogenetic and functional relationships in pastures and meadows from the North Adriatic Karst

Probably due to its phytogeographic position, the grasslands in the North Adriatic Karst are among the richest grasslands in the world and harbour the highest small-scale density of plant species found in terrestrial habitats. Different moisture and soil conditions determine distinct vegetation types, such as meadows, composed by mesophyllous plants and on mesic conditions, and semi-natural pastures, composed by sclerophyllous plants and on oligotrophic conditions. Even though plants in these two vegetation types differ in some of their attributes, their functional and phylogenetic relationships remain to be tested. We used a dataset comprising 180 species, in which 48 plots in the meadows and 52 plots in the pastures had been sampled, and tested the phylogenetic and functional relationships between the two vegetation types. The pastures contained more original species, but both the pastures and the meadows are expected to be important to increase biodiversity at landscape level. Different community assembly processes occurred in the two vegetation types, with limiting similarity leading to functional overdispersion in the meadows and environmental filtering leading to functional clustering in the pastures. Overall, traits were convergent, leading to a clustered phylogenetic structure in the meadows, probably due to pair-wise competition, and an overdispersed phylogenetic structure in the pastures, where species from different clades were filtered by the oligotrophic conditions. Transhumance may have contributed to the random pattern of trait diversity we found across the nodes of the phylogenetic tree.

Germination and survival of endangered Pulsatilla grandis (ranunculaceae) after artificial seeding, as affected by various disturbances

Pulsatilla grandis is a rare and endangered species in Central Europe. A field experiment was set up to test the effects of disturbances on its germination and survival rates after artificial seeding. Disturbances were simulated by the following treatments: burning, hoeing, and removal of vegetation. The germination percentage decreased rapidly with time, to only 2% in 2-year-old fruits. The germination rate of fresh fruits was the highest in hoed plots (29.2 ± 12.9%), followed by removedvegetation plots (21.8 ± 17.3%) and burned plots (1.8 ± 2.2%). No germination was observed in control plots. The survival rate of seedlings was monitored over the next 5 years. In the year following the treatment, all the seedlings survived in the burned plots; in the hoed and in removed-vegetation plots, survival rates were 38.5 ± 2 and 55 ± 27%, respectively. Approximately half of them were alive after 5 years. Grassland vegetation in burned quadrates recovered very quickly, whereas in other disturbed plots the numbers ...

Public attitudes and opinions as dimensions of efficient management with extensive meadows in Natura 2000 area.

Over time, grassland use has changed from traditional (extensive) to intensive agricultural management, a change which has caused biodiversity loss in the European grassland area. To save Europes biodiversity, the most important measure was the establishment of the Natura 2000 network. Goričko Landscape Park in Slovenia is in Natura 2000 to preserve its traditional and extensive small-scale farming. The aims of this research were to identify potential obstacles to proper management of the extensively used meadows in this region and identify major factors that would affect such management in order to prepare more appropriate strategies for habitat conservation. The data was collected by online survey and in paper and pencil format. Based on Principal Component Analysis (PCA), Confirmatory Factor Analysis and Structural Equation Modelling, we can conclude that less than a half of 228 respondents can identify what activities are permitted in a Natura 2000 area, which indicates a lack of knowledge about Natura 2000. The majority agree with meadow management in the welfare of protected plants and animals but would accept management under stricter regulations only if accompanied by higher subsidies in for management under stricter regulations. These respondents are not prepared to participate in measures for preserving biodiversity without beneficiaries. Respondents have in average a positive opinion toward protected plants and animals, but the procedure for obtaining environmental subsidies for meadows seems to them too complicated. Although the majority of respondents do not see a Natura 2000 area as a place for quality living, it is the factor with the highest significant effect on willingness to participate in measures to preserve biodiversity.

High potential of sub-Mediterranean dry grasslands for sheep epizoochory

Abstract There is a general decline of grasslands across Europe due to habitat loss and degradation. Ensuring plant dispersal thus becomes a key process for preserving grassland patches in all scales. We examined diaspore dispersal by sheep epizoochory in the pastures of the North Adriatic Karst (NW Slovenia) and determined the qualitative and quantitative features of diaspores in fur. We recorded 25,650 diaspores of 141 plant taxa (with 107 taxa and 23,350 diaspores determined to species level), using three different methods: (i) the “whole-coat method”, (ii) the “part-of-thecoat method” and (iii) a “seedling emergence method”. A comparison of these techniques revealed that the “wholecoat method” provided the highest number of diaspores and plant species. All diaspores were clustered into five emergent groups based on seven functional traits (diaspore weight, length, width, height, volume, specific weight and the diaspore surface structure). Our research revealed that sheep represent an important dispersal vector, since about half of the plant species recorded in the pastures were found as diaspores in fur. This study contributes to knowledge about the modes of seed dispersal in seminatural grasslands. Taking into account that livestock play a key role in vegetation dynamics, understanding their effects on seed dispersal is essential for conservation and restoration of these species-rich grassland communities.

Trophic-level differences in functional composition of the Nardus grassland vegetation

Abstract In this study, we examined floristic and functional composition of Nardus grassland of the highlands of NE Slovenia. The data-set included 55 relevés, 59 plant species, and 17 plant functional traits (PFT). The TWINSPAN classification resulted in two plant communities; calcifuge species (G1_oligotr) and another group of species characteristic of mesotrophic meadow (G2_mesotr). On the basis of selected PFT 11 out of 17 differ significantly between the groups. Group G1_oligotr had higher community-weighted mean trait values for chamaephytes (G1 = 0.09; G2 = 0.02), geophytes (G1 = 0.03; G2= 0.01), competitors (G1 = 0.43; G2 = 0.41) and plants that start flowering later (G1 = 142.84; G2 = 136.69). On the other side was G2_mesotr represented with more plants that are therophytes (G1 = 0.04; G2 = 0.09), creeping (G1 = 0.01; G2 = 0.12) and short-lived (G1 = 0.04; G2 = 0.11) and have longer flowering period (G1 = 3.24; G2 = 3.60). Differences may reflect the stronger effect of disturbance and eutrophication in G2_mesotr, probably due to intensification of grassland management (grazing) in the region. Our findings are significant in understanding the relative influence of environmental stress and disturbance within Nardus grasslands, and this may have important implications for their conservation management.

Factors Affecting Composition of Gravel Bar Vegetation in Middle Reach of a Lowland River

ABSTRACT In this study, we investigated plant communities in relation to site-specific morphological properties and sediment structure on gravel bars along the middle Drava River in Slovenia. We sampled 143 plots of 5 × 5 m using species cover-abundance estimates. In addition, we considered the following habitat physical variables: elevation above the water line, texture of the substrate (silt, sand, gravel content) and bar age. Based on TWINSPAN method, we distinguished four vegetation types: (G1) xerophilic and thermophilic ruderal stage; (G2) stage with sparse and herb-rich ruderal vegetation with species of semi-dry grasslands; (G3) initial vegetation stage of frequently disturbed mesotrophic and eutrophic sites and (G4) tall-willow stage. The most important factors determining a bars vegetation were elevation and gravel content. Our study shows that gravel bars of the middle Drava river system form a suitable habitats for species-rich plant communities. Their diversity is a function of high spatial heterogeneity coupled with the opposing forces of stress and disturbance.

Spatio-temporal patterns along a primary succession on alluvial sediments

Dynamic alluvial landscapes offer many possibilities to study primary succession processes on newly developed habitats. However, within the Central European environmental conditions, where watercourses and their riparian spaces are under severe anthropogenic pressures — water regulation, deforestation, lowering of groundwater — natural processes are limited. We studied primary succession on alluvial stream deposits in an artificial lake, where we aimed to follow the terrestrialisation rate and habitat turnover, along with plant species richness and composition across successional stages. In 30 years, a pristine white-willow riparian forest developed. One half of the initially aquatic habitat became terrestrial. The frequency of change, studied on 11250 quadrats 10×10 m each (on a scale from “no change” to 8 changes) and the mean of change per habitat type (most of the habitats changed 2 to 3 times) revealed only one successional trajectory. The percentage flow chart showed a deterministic pathway of succession. The “time since formation” of a terrestrial habitat shows that more than 20% of the lake was terrestrialised within in the first ten years. We studied species richness and composition along three composed transects, following successional stages. We found that the newly assembled riparian white willow woodland has a surprisingly low colonisation rate of plant species.