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
was recorded for the first time in Bulgaria and a new locality of the rare bryophyte
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
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.
Until now, a complete checklist of
-dwelling testate amoebae in Bulgaria has never been published. Records for species diversity and distribution in the country were scattered in many faunistic and ...ecological publications. The aim of the present study is to summarise all data for the species distribution at the level of country by reviewing the existing literature and by additional data obtained in our research over the past two years.
The checklist comprises 171 species, classified into 43 genera, 20 families, three orders, three classes and three phyla. We present data for 16 new
-dwelling testate amoebae in Bulgaria and new distribution data for 134 species. Of them, 99 species are recorded from Stara Planina Mt., for which there was no available data to date. Additionally are recorded 69 new species for Pirin Mt., 21 for Vitosha Mt. and 18 for Rila Mt. Thirty six species are synonymised according to the latest taxonomic changes. Two misidentified taxa (
Penard, 1902 and Difflugia compressa var. africana Gauthier-Lièvre et Thomas, 1958) are transferred into valid species
and
, respectively. Three of the recorded species have not been included in the checklist, because they are currently not refering to testate amoebae (
(Auerbach 1856) and
Korotneef, 1879 are gymnamoebae (naked amoebae) and
(Penard 1904) =
(Penard 1904) is freshwater foraminifera).
As a distinctive component of the cultural landscape in Eurasia, burial mounds are well known for their historical value. Recently their role as biodiversity hotspots, especially in the homogenous ...agricultural landscape, has become particularly important. Archaeological excavations, although necessary, are destructive to the natural elements on the mounds. Restoration and vegetation recovery after such disturbances are needed for the preservation of biodiversity and for the cultural landscape integrity. In this study, we aimed to find out how effective is the natural vegetation recovery on the mounds after archaeological excavations. Successional stages between 2- and 30-years post-excavations have been studied. Vegetation sampling was performed on 15 mounds within 300 plots (1 × 1 m). Spontaneous succession was found to start immediately, and during the first decade, anthropophytes prevailed. In the subsequent years, their cover significantly decreased at the expense of species typical for the natural communities in the surroundings. Total species richness increased with the successional age and the vegetation composition became more similar to the semi-natural communities commonly established on mounds in Bulgaria. In the advanced successional stages, we registered a high rate of heterogeneity on the mounds, facilitated by the establishment of target plant species with different ecological requirements, including bryophytes. Provided the obtained results, we conclude that the natural vegetation recovery on the excavated and subsequently recovered mounds were very successful, and the current practice must continue in the future.
The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genusSphagnum-the main peat-former and ecosystem engineer in northern ...peatlands-remains unclear. We measured length growth and net primary production (NPP) of two abundantSphagnumspecies across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers onSphagnumgrowth. Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denserSphagnum fuscumgrowing on hummocks had weaker responses to climatic variation than the larger and looserSphagnum magellanicumgrowing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth forS. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influencedSphagnumgrowth indirectly by affecting moss shoot density. Synthesis. Our results imply that in a warmer climate,S. magellanicumwill increase length growth as long as precipitation is not reduced, whileS. fuscumis more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species-specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.
The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genus Sphagnum—the main peat‐former and ecosystem engineer in northern ...peatlands—remains unclear.
We measured length growth and net primary production (NPP) of two abundant Sphagnum species across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers on Sphagnum growth.
Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denser Sphagnum fuscum growing on hummocks had weaker responses to climatic variation than the larger and looser Sphagnum magellanicum growing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth for S. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influenced Sphagnum growth indirectly by affecting moss shoot density.
Synthesis. Our results imply that in a warmer climate, S. magellanicum will increase length growth as long as precipitation is not reduced, while S. fuscum is more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species‐specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.
We measured growth in two species from the peat forming bryophyte genus Sphagnum (peat mosses) across the Holarctic. Employing structural equation models, we explored how indirect and direct drivers, such as weather variables, PAR, water table, nitrogen and vascular plant cover affect growth. Species‐specific responses may affect competitive outcomes in a changing environment, and potentially the carbon sink function of peatlands.
Aims
Developing a hierarchical classification system for classes, orders and alliances of the diverse dry grasslands of the Central and Eastern Balkan Peninsula and translating this into an ...electronic expert system (ES) for the automatic assignment of plots.
Location
Serbia, Kosovo, North Macedonia, Bulgaria and northern Greece.
Methods
We extracted 5734 plots from the Balkan Dry Grassland Database corresponding to eight classes of dry grasslands reported from the region, using the EuroVegChecklist ES. This data set and later the plots within each derived subunit were subjected to a new numerical approach: starting with an initial partitioning (expert‐interpreted TWINSPAN classification), diagnostic species were determined based on their phi‐values for the target vegetation type and the differences in phi‐values to the next similar types. These diagnostic species were fed into an ES to create a new partitioning, a procedure which was iterated until diagnostic species and species of the ES converged. Then the same approach was applied within each of the derived units to define the units of the next‐lower level.
Results
The iterative cluster optimisation (ICO) converged in all cases. The resulting hierarchical expert system (HES) classified 95% of all plots to alliances. We distinguished four classes with eight orders and 12 alliances: (1) Tuberarietea guttatae (Romuleion); (2) Stipo‐Brachypodietea distachyi (Clinopodio alpini‐Thymion striati); (3) Festuco‐Brometea with Brachypodietalia pinnati (Chrysopogono‐Danthonion calycinae and Cirsio‐Brachypodion pinnati), Festucetalia valesiacae (Festucion valesiacae), an unnamed order of rocky steppes (with Pimpinello‐Thymion zygioidis) and Koelerietalia splendentis (Centaureo‐Bromion fibrosi, Saturejion montanae and Diantho haematocalycis‐Festucion hirtovaginatae); (four) Koelerio‐Corynephoretea with Sedo acris‐Festucetalia (Festucion vaginatae) and Trifolio arvensis‐Festucetalia ovinae (Armerio rumelicae‐Potentillion and Minuartio montanae‐Poion molinerii all. nov.).
Conclusions
We created a unified hierarchical classification with an electronic ES using diagnostic species defined by phi‐values. Our new approach (ICO‐HES: iterative cluster optimisation for hierarchical expert systems) allows dividing large data sets into meaningful units at several hierarchical levels, and thus has high potential for complex classifications. Importantly, it overcomes the divide between ES species and diagnostic species and re‐unites them into one concept.
We classified the dry grasslands of the Central and Eastern Balkan Peninsula with a large dataset and a new classification approach, called iterative cluster optimisation for hierarchical expert systems (ICO‐HES). We distinguish and describe 12 alliances, placed in eight orders and four classes, with one alliance and one order new to science. ICO‐HES has great potential also for other classifications as it is hierarchical, leaves very few plots unclassified and unites expert system species and diagnostic species into one concept.
The names of all mosses published up to the end of August 2011 in the countries of the Mediterranean basin, the Macaronesian Islands and Bulgaria are compiled in an annotated checklist. The list ...comprises accepted names and synonyms, and provides explanatory annotations for ambiguous and disputed names. Literature references supporting the reports in each individual area are given only for taxa reported once or in a single locality. A total of 1168 accepted species and 81 infraspecific taxa are reported from the whole area.
Bryophyte species composition and 26 common physico-chemical and inorganic chemical parameters were assessed at 23 selected sites in the Maritsa River (BG) over a 4-year period. Principal components ...analyses (PCA) of both bryophytes and water variables distinguished different locations in the ecosystem. The data imply that the content of elements measured in bryophytes represents river contamination, while species compositional patterns reflect hydromorphology and general degradation. This study for the first time combined aquatic bryophyte occurrence, the bioaccumulation of 17 macro-and microelements in 17 species, and 26 water factors by principal components analysis (PCA) in an assessment of river pollution.
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