FLORA, MYCOTA AND VEGETATION OF KUPENA RESERVE (RODOPI MOUNTAINS, BULGARIA)

The paper represents results from recent complex studies of flora, mycota and vegetation within the Kupena Reserve (Rodopi Mts, Bulgaria). Twenty three species, referred to 2 divisions, 4 classes and 16 families are recorded for the bryoflora. The vascular flora is presented by 368 species from 57 families, 121 of which are considered as medicinal plants. Eighty seven species of larger ascomycetes and basidiomycetes are found and reported for first time in the reserve. Four of them are of a high conservation value. The vegetation cover is consisted of mixed and monodominant deciduous and coniferous forests, as well as of mire, riverbank and mesic grasslands. Thirteen types of habitats according to the Habitats Directive classification have been recorded within the reserve

First Survey of the Vascular and Cryptogam Flora on Bulgaria’s Ancient Mounds

This work represents the first study of the floristic diversity on Bulgaria’s ancient mounds. The objective of this research was to assess the importance of the mounds for the preservation of the native vascular and cryptogam flora. Our sampling design included 111 ancient mounds distributed throughout the country. We recorded a total of 1059 vascular plants, 58 bryophytes and 61 lichen taxa. Despite their small area, the mounds were shown to preserve nearly a quarter of the Bulgarian flora. The vegetation cover on the mounds included 61% perennials indicating a long-term persistence and stability. The majority (98%) of the established vascular plants were native species. Although the conservation significance of the vascular plant species were not common, we recorded 2 critically endangered, 9 endangered and 14 Balkan endemics during the present study. The lichen Arthopyrenia salicis was recorded for the first time in Bulgaria and a new locality of the rare bryophyte Ceratodon conicus was discovered. The established compositional difference between plots from the northern and southern slopes of the mounds (88.95%) is a testament to the high local habitat diversity. The prevalence of species characteristic for Festuco-Brometea suggests that the mounds preserve fragments of native grasslands and steppes. The variation in cover of agricultural and other human modified areas in the mounds’ immediate surroundings did not substantially affect their species richness. We argue that the ancient mounds should be taken into consideration in future green space planning

Scrutinizing functional patterns and assembly rules estimated from transect data

Transect sampling is routinely used in vegetation science. Yet, the reliability of this type of sampling for assessing community assembly rules has not been scrutinized. Local interactions and limited dispersal have essential role in the organization of plant communities. Information about vegetation patterns in the neighbourhood is probably crucial for assessing and understanding community assembly rules. The "one-dimensional" transect sampling does not provide information about adjacent vegetation patterns in the neighbourhood, therefore vegetation characteristics and assembly rules might be incorrectly estimated from transect data. In this study, alkaline, loess and sand grasslands were sampled. Presence of plant species was recorded in large elongated grids of 10 x 1040 units of 5x5cm resolution, which corresponded to a spatial extent of 50 cm x 5200 cm. Vegetation characteristics (taxon-based alpha and beta diversity and trait-based functional diversity) derived from the central 1x1040 units long transect were compared to characteristics derived from the full grid data. In the second analysis the central transect was analyzed by variography and then the patterns in the neighbouring transects were approximated by kriging. These simulated patterns were compared to the original patterns of the neighbouring transects. Community assembly rules were assessed by comparing realized patterns of functional diversity to null models. The main vegetation characteristics were similar between sampling types. Abundances and patterns of abundant species were reliably estimated from transects while the patterns of rare species varied between sampling types. Functional diversity (expressed by Rao index) was also properly estimated from transects. Local vegetation characteristics were autocorrelated within 50cm in each grasslands. Consequently, the patterns of adjacent transects, running in the close neighbourhood, could be well approximated by geostatistics. The strongest spatial dependence appeared in alkaline grasslands. Due to differences in the abundance estimates of rare species, null models derived from grids and transect were slightly different with more power in the case of grid-based data. However, the spatial structure of the dominant species and the related assembly rules did not differ between sampling types. Due to strong autocorrelations at fine spatial scales, transect sampling proved to be effective for estimating functional patterns and assembly rules

How plot shape and spatial arrangement affect plant species richness counts: implications for sampling design and rarefaction analyses

Questions: How does the spatial configuration of sampling units influence recorded plant species richness values at small spatial scales? What are the consequences of these findings for sampling methodology and rarefaction analyses? Location: Six semi‐natural grasslands in Western Eurasia (France, Germany, Bulgaria, Hungary, Italy, Turkey). Methods: In each site we established six blocks of 40 cm × 280 cm, subdivided into 5 cm × 5 cm micro‐quadrats, on which we recorded vascular plant species presence with the rooted (all sites) and shoot (four sites) presence method. Data of these micro‐quadrats were then combined to achieve larger sampling units of 0.01, 0.04 and 0.16 m² grain size with six different spatial configurations (square, 4:1 rectangle, 16:1 rectangle, three variants of discontiguous randomly placed micro‐quadrats). The effect of the spatial configurations on species richness was quantified as relative richness compared to the mean richness of the square of the same surface area. Results: Square sampling units had significantly lower species richness than other spatial configurations in all countries. For 4:1 and 16:1 rectangles, the increase of rooted richness was on average about 2% and 8%, respectively. In contrast, the average richness increase for discontiguous configurations was 7%, 17% and 40%. In general, increases were higher with shoot presence than with rooted presence. Overall, the patterns of richness increase were highly consistent across six countries, three grain sizes and two recording methods. Conclusions: Our findings suggest that the shape of sampling units has negligible effects on species richness values when the length–width ratio is up to 4:1, and the effects remain small even for more elongated contiguous configurations. In contrast, results from discontiguous sampling units are not directly comparable with those of contiguous sampling units, and are strongly confounded by spatial extent. This is particularly problematic for rarefaction studies where spatial extent is often not controlled for. We suggest that the concept of effective area is a useful tool to report effects of spatial configuration on richness values, and introduce species–extent relationships (SERs) to describe richness increases of different spatial configurations of sampling units