Research Paper |
Corresponding author: Michal Hájek ( hajek@sci.muni.cz ) Academic editor: Jozef Šibík
© 2021 Michal Hájek, Petra Hájková, Iva Apostolova, Desislava Sopotlieva, Irina Goia, Daniel Dítě.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Hájek M, Hájková P, Apostolova I, Sopotlieva D, Goia I, Dítě D (2021) The vegetation of rich fens (Sphagno warnstorfii-Tomentypnion nitentis) at the southeastern margins of their European range. Vegetation Classification and Survey 2: 177-190. https://doi.org/10.3897/VCS/2021/69118
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Question: Rich fens of the Sphagno warnstorfii-Tomentypnion nitentis alliance require a specific combination of base richness and climate to occur. Their rarity at the southeastern margins of their European range has previously prevented rigorous vegetation classification. We asked how many associations may be delimited here and whether some of them are restricted to the high Balkan Mountains showing high endemicity. Study area: Entire territories of Bulgaria and Romania. Methods: We compiled all available vegetation-plot records, including some hitherto unprocessed data. We classified them by both divisive (modified TWINSPAN) and agglomerative (beta-flexible clustering) numerical classification method, with OPTIMCLASS1 applied to set the number of clusters. A semi-supervised approach (k-means) was additionally applied to confirm the classification of Southern-Carpathian (Romania) rich fens, where some Balkan taxa occur. Differences in base richness and elevation were tested by one-way ANOVA with Tukey’s pairwise test. Results: Three associations were delimited and all three occur in Bulgaria, from where only one association had been previously reported. Two associations characterised by Sphagnum contortum and Balkan and Southern-European species occur in Bulgaria, but not in Romania, one at lower elevations around 1,200 m, and one at higher elevations around 2,000 m where pH is lower. One lower-elevation (around 1,300 m) association with S. warnstorfii and S. teres is shared between Romania, Bulgaria and Central Europe. Conclusions: We have described a new high-mountain association, with two subassociations that differ by successional stage and dominant peat moss species (S. contortum and S. warnstorfii, respectively). These subassociations could be reconsidered when more data from other Balkan countries are available. Rich fens in southeastern Europe are rare, have a diverse vegetation, and are deserving of the further attention of nature conservation authorities and vegetation scientists.
Taxonomic reference: The nomenclature was harmonized following The Euro+Med PlantBase (
Syntaxonomic reference:
Balkans, Bulgaria, endemic and relict species, mires, rich fens, Romania, Sphagno warnstorfii-Tomentypnion nitentis, vegetation survey
Rich fens, a habitat in which acidicole and calcicole species both occur, are one of the most important wetland habitats in terms of biodiversity conservation, being increasingly endangered across Europe (
In Romania, a neighbouring country also at the edge of the range for calcium-tolerant peat mosses and fen specialists (
In this study we ask whether some associations with S. warnstorfii can be distinguished from Bulgaria, along with the previously reported Geo coccinei-Sphagnetum contorti, and whether Southern Carpathian rich fens may belong to the same association as Bulgarian ones. The output from our study is a classification of Bulgarian and Romanian rich fens at the association level.
To answer our two questions, we merged the existing limited datasets from previous studies (Romanian, Bulgarian high-mountain and Bulgarian low-elevation) into one, and added new original data from the Vitosha Mts (Bulgaria) sampled in 2006, after the
We measured water pH and conductivity from the centre of the patch of fen being studied using portable instruments (mostly HACH HQ40d or CM 101 and PH 119, Snail Instruments). A shallow hole was dug before each measurement was taken to allow a pool of water to form. For testing the differences between associations, we further combined these two variables into a single variable called adjusted pH (
As a first step, we ran unsupervised hierarchical classifications, using two different approaches. One was based on partitioning the major gradients (modified TWINSPAN,
As a second step, we tested whether Southern Carpathian rich fens (Romania) belong to the same association as Bulgarian high-mountain rich fens, and whether some low-elevation fens of Bulgaria belong to the same association as Romanian S. warnstorfii rich fens. The goal was to clarify the national-level syntaxonomical synopses. For this purpose, we constructed three species groups (named Pinguicula balcanica group, Sphagnum warnstorfii group and Geum coccineum group; cf. Table
Species groups used in the formal definitions for the three associations before the run of semi-supervised k-means classification. The Sphagno contorti-Primuletum exiguae association (10 relevés from Bulgaria) had been defined by the presence of the Pinguicula balcanica group (at least two species had to be present), the Sphagno warnstorfii-Eriophoretum latifolii association (17 relevés, out of which two are from Bulgaria) is based on the presence of the Spagnum warnstorfii group (at least two species had to be present) and the Geo coccinei-Sphagnetum contorti association (27 relevés from Bulgaria) is based on the presence of the Geum coccineum group (at least two species had to be present) and the absence of the Pinguicula balcanica group.
Name of species group | Taxa involved |
---|---|
Pinguicula balcanica | Primula frondosa subsp. exigua, Pinguicula balcanica, Carex bulgarica, Plantago gentianoides |
Sphagnum warnstorfii | Sphagnum warnstorfii, S. angustifolium, Valeriana simplicifolia, Calliergon giganteum |
Geum coccineum | Sphagnum contortum, Geum coccineum, Juncus thomasii, Veratrum lobelianum |
In the synoptic table, we consider a species as diagnostic if it has a statistically significant association with a cluster (P <0.05; Fisher exact test). We also present the species occurring in at least 20% of vegetation-plot records.
Differences among associations in edaphic and climatic variables were visualised by box-and-whisker plots showing medians, interquartile ranges, extremes and outliers, and tested by one-way ANOVA with Tukey’s pairwise test with Copenhaver-Holland correction. Water conductivity was log-transformed prior to testing to achieve normal distribution. Normality of the data was tested using the Anderson-Darling normality test. All analyses were conducted using the Past 4 software (
Based on the OPTIMCLASS 1 algorithm, modified TWINSPAN resulted in five clusters, while beta-flexible clustering resulted in four clusters. However, their interpretation is the same (Figures
The results of unsupervised divisive classification (modified Twinspan) at the level of five clusters (the number set according to the results of the Optimclass method): dendrogram, species showing the highest fidelity to a cluster, number of relevés in a cluster, involved countries or regions (with minor country in brackets), and expert syntaxonomical interpretation of a cluster.
The results of unsupervised agglomerative classification (beta -0.25; Bray-Curtis distance) at the level of four clusters (the number set according to the results of the Optimclass method): dendrogram, species showing the highest fidelity to a cluster, number of relevés in a cluster, involved countries or regions (with minor country in brackets), and expert syntaxonomical interpretation of a cluster.
When we set three formally defined vegetation types (Bulgarian high-mountain rich fens, low-elevation S. warnstorfii rich fens, and Bulgarian S. contortum rich fens) as predefined groups and ran semi-supervised k-means, the small Romanian cluster with Ligularia sibirica also appeared, but this group included only three relevés with Ligularia sibirica and S. warnstorfii. No Romanian relevé was assigned to the cluster of Balkan high-mountain rich fens. A single Romanian relevé was assigned to the cluster of Bulgarian S. contortum rich fens, but it lacks SE-European species and is transitional to poor fens, making its assignment to the Geo coccinei-Sphagnetum contorti association inappropriate.
We interpret the cluster of Bulgarian high-mountain rich fens as a new plant association, with a distribution range restricted to the Balkans, and we describe it formally in this paper with the name Sphagno contorti-Primuletum exiguae. In approximately half of the relevés, Sphagnum warnstorfii dominates, with certain changes in species composition suggesting advanced succession; we suggest treating these as the sphagnetosum warnstorfii subassociation.
We further interpret the cluster of low-elevation S. warnstorfii rich fens as the Sphagno warnstorfii-Eriophoretum latifolii association and report it as a new association for Bulgaria. Finally, we discovered that the Geo coccinei-Sphagnetum contorti association (cluster of Bulgarian S. contortum rich fens) does not occur in Romania and is restricted to the Balkans. A small cluster of Romanian rich fens characterised by L. sibirica and Epipactis palustris were not definitively interpreted syntaxonomically. However, as these relevés were dominated by peat moss species and high-mountain species were absent, we merged it with the Sphagno warnstorfii-Eriophoretum latifolii association, where it may be considered as a separate subassociation.
The synoptic table shows the three delimited associations resulted from the beta-flexible classification at the level of four clusters, with the two clusters we interpreted as the same association Sphagno warnstorfii-Eriophoretum latifolii merged (Table
Synoptic table in percentage frequency. Species are sorted according to decreasing fidelity (unstandardized phi-coefficient) to an association. Species with a statistically significant fidelity to a cluster (Fisher exact test < 0.05) are considered diagnostic and highlighted by grey shading.
Associations | 1 | 2 | 3 |
---|---|---|---|
number of relevés | 13 | 30 | 27 |
from Bulgaria | 13 | 5 | 27 |
from Romania | 0 | 25 | 0 |
Alliance species ( |
|||
Sphagnum contortum | 77 | 30 | 96 |
Sphagnum warnstorfii | 46 | 67 | 4 |
Sphagnum teres | 46 | 63 | 19 |
Paludella squarrosa | 0 | 7 | 0 |
Aulacomnium palustre | 38 | 73 | 67 |
Tomentypnum nitens | 8 | 27 | 11 |
Diagnostic species of individual associations | |||
1. Sphagno contorti-Primuletum exiguae | |||
Primula frondosa subsp. exigua | 77 | 0 | 0 |
Pinguicula balcanica | 77 | 3 | 4 |
Taraxacum sect. Alpina | 85 | 3 | 0 |
Cardamine rivularis | 85 | 30 | 0 |
Sesleria comosa | 38 | 0 | 0 |
Gentianella bulgarica | 38 | 0 | 0 |
Trichophorum cespitosum | 38 | 0 | 0 |
Carex bulgarica | 38 | 0 | 0 |
Cirsium heterotrichum | 38 | 0 | 0 |
Soldanella pindicola | 46 | 0 | 4 |
Plantago gentianoides | 46 | 7 | 0 |
Vaccinium uliginosum | 31 | 0 | 0 |
Crocus veluchensis | 31 | 0 | 0 |
Carex nigra | 100 | 60 | 33 |
2. Sphagno warnstorfii-Eriophoretum latifoliae | |||
Valeriana dioica subsp. simplicifolia | 0 | 43 | 0 |
Galium uliginosum | 0 | 40 | 0 |
Sphagnum angustifolium | 0 | 33 | 0 |
Agrostis stolonifera | 0 | 30 | 0 |
Calliergon giganteum | 0 | 33 | 4 |
Straminergon stramineum | 31 | 57 | 11 |
3. Geo coccinei-Sphagnetum contorti | |||
Holcus lanatus | 0 | 7 | 74 |
Myosotis scorpioides agg. | 23 | 30 | 100 |
Briza media | 0 | 10 | 59 |
Pilosella caespitosa | 0 | 3 | 44 |
Juncus effusus | 0 | 27 | 70 |
Plagiomnium affine agg. | 8 | 20 | 67 |
Calliergonella cuspidata | 0 | 67 | 96 |
Rumex acetosa | 0 | 3 | 41 |
Cynosurus cristatus | 0 | 3 | 41 |
Ranunculus acris | 8 | 10 | 48 |
Prunella vulgaris | 0 | 30 | 63 |
Oenanthe banatica | 0 | 0 | 26 |
Ranunculus flammula | 0 | 0 | 26 |
Mentha arvensis | 0 | 0 | 26 |
Carex panicea | 15 | 20 | 59 |
Galium palustre | 0 | 57 | 81 |
Lysimachia vulgaris | 0 | 10 | 41 |
Crepis paludosa | 0 | 20 | 52 |
Species with frequency above 20% in the entire data set | |||
Carex echinata | 85 | 87 | 100 |
Potentilla erecta | 46 | 93 | 96 |
Eriophorum latifolium | 100 | 67 | 89 |
Festuca rubra | 77 | 83 | 67 |
Parnassia palustris | 69 | 60 | 85 |
Luzula sudetica | 92 | 63 | 70 |
Agrostis canina | 62 | 70 | 70 |
Nardus stricta | 100 | 57 | 56 |
Carex rostrata | 8 | 70 | 52 |
Bryum pseudotriquetrum | 54 | 50 | 52 |
Epilobium palustre | 23 | 43 | 70 |
Warnstorfia exannulata | 69 | 60 | 22 |
Climacium dendroides | 31 | 40 | 63 |
Dactylorhiza cordigera | 69 | 37 | 48 |
Geum coccineum | 85 | 7 | 67 |
Carex flava | 8 | 53 | 44 |
Anthoxanthum odoratum | 46 | 23 | 56 |
Alchemilla vulgaris agg. | 31 | 33 | 48 |
Aneura pinguis | 54 | 40 | 26 |
Juncus articulatus | 23 | 30 | 48 |
Deschampsia cespitosa | 62 | 37 | 19 |
Campylium stellatum | 46 | 37 | 26 |
Caltha palustris | 15 | 27 | 48 |
Eriophorum angustifolium | 31 | 27 | 41 |
Succisa pratensis | 38 | 13 | 52 |
Sphagnum subsecundum | 38 | 37 | 22 |
Hamatocaulis vernicosus | 0 | 43 | 33 |
Philonotis fontana | 15 | 17 | 52 |
Full table of phytosociological relevés for the two associations new to Bulgaria. Only relevés from Bulgaria are presented.
Relevé number | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Original turboveg number | 1 | 585 | 359 | 360 | 352 | 79 | 362 | 582 | 586 | 627 | 182 | 10 | 67 | 510 | 504 | 50 | 520 | 131 |
Relevé area (m2) | 6 | 16 | 16 | 16 | 16 | 10 | 16 | 16 | 16 | 16 | 16 | 9 | 4 | 16 | 16 | 25 | 16 | 8 |
Herb cover (%) | 85 | 65 | 80 | 85 | 75 | 80 | 75 | 65 | 70 | 60 | 80 | 50 | 70 | 70 | 75 | 85 | 50 | 60 |
Moss cover (%) | 60 | 20 | 75 | 70 | 75 | 70 | 50 | 85 | 80 | 100 | 70 | 90 | 90 | 80 | 90 | 85 | 95 | 60 |
Water pH | . | 6.1 | 5.9 | 5.7 | 5.9 | 5.7 | 5.5 | 6.1 | 5.4 | 5.0 | 5.4 | . | . | 6.0 | 5.8 | 6.9 | 5.6 | 5.2 |
Water conductivity (µS.cm-1) | . | 73 | 60 | 47 | 22 | 5 | 44 | 80 | 65 | 28 | 14 | . | . | 55 | 80 | 50 | 73 | 39 |
Differential species of species of Sphagno contorti-Primuletum exiguae | ||||||||||||||||||
Pinguicula balcanica | 1 | + | + | + | . | 2a | 2a | + | . | + | . | + | 1 | . | . | . | . | + |
Cardamine rivularis | + | 1 | 1 | 1 | 1 | 1 | . | + | + | r | + | 1 | . | . | . | . | . | . |
Taraxacum sect. Alpina | . | + | + | 1 | r | + | + | + | + | r | 1 | 2a | . | . | . | . | . | . |
Primula frondosa subsp. exigua | + | . | 2a | 15 | 2m | 2m | 2b | . | . | + | 1 | 1 | + | . | . | . | . | . |
subass. typicum | ||||||||||||||||||
Bryum pseudotriquetrum | + | . | 2a | 2a | + | 2a | + | + | . | . | . | . | . | . | . | . | . | . |
Campylium stellatum | . | . | + | 1 | + | + | + | 2a | . | . | . | . | . | . | . | . | . | . |
Soldanella pindicola | . | . | 1 | 2b | 1 | + | + | . | . | . | . | . | + | . | . | . | . | . |
Veratrum lobelianum | + | + | r | + | r | . | . | + | . | . | . | . | . | . | . | . | . | . |
subass. sphagnetosum warnstorfii | ||||||||||||||||||
Eriophorum vaginatum | . | . | . | . | . | . | . | + | + | . | . | 1 | . | . | . | . | . | . |
Trichophorum cespitosum | 2m | . | . | . | . | . | . | 1 | + | 2a | . | . | 2a | . | . | . | . | . |
Differential species of Sphagno warnstorfii-Eriophoretum latifolii | ||||||||||||||||||
Carex rostrata | . | . | . | . | . | . | . | . | + | . | . | . | . | 2a | 1 | 1 | . | . |
Juncus effusus | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | + | 1 |
Galium palustre | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | 1 | 2a | . |
Carex canescens | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | 2b | 1 | . |
Alliance species | ||||||||||||||||||
Sphagnum contortum | . | 1 | 2b | 2a | 3 | 2a | 2b | 1 | 2a | 1 | + | . | . | . | . | . | . | . |
Sphagnum teres | 1 | 2a | . | . | . | . | . | 2a | 2b | 2b | 1 | . | . | 3 | + | 4 | 4 | . |
Sphagnum warnstorfii | . | . | . | . | . | . | . | 4 | 1 | 4 | 4 | 4 | 4 | 2a | . | . | . | 2a |
Aulacomnium palustre | 1 | + | . | . | . | . | . | . | + | . | + | 2a | . | 2a | + | . | 1 | . |
Tomentypnum nitens | . | . | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . |
Other mire species | ||||||||||||||||||
Eriophorum latifolium | + | 2a | 3 | 2b | 2a | 2a | 2b | 2a | 2a | 1 | 1 | 2a | 2a | 2a | 2b | 2b | 1 | 1 |
Carex nigra | 3 | 3 | 2a | 2a | 3 | 2a | 2a | 2b | 2a | 2a | 2a | 2a | + | + | 1 | . | . | 1 |
Carex echinata | + | . | + | + | + | 2a | 1 | 1 | . | 2a | 2a | + | 1 | 1 | + | 2a | 2a | 2a |
Agrostis canina | + | + | . | 1 | 1 | . | 1 | + | + | . | . | 1 | . | 1 | + | + | 2m | + |
Parnassia palustris | r | + | + | + | 1 | . | . | + | + | + | + | . | . | 1 | + | . | + | 1 |
Dactylorhiza cordigera | 1 | 1 | 1 | 1 | r | . | . | + | + | + | 1 | . | . | . | 1 | 2a | + | r |
Warnstorfia exannulata | + | 1 | 1 | 1 | 1 | 3 | . | . | + | + | . | + | . | . | . | 2b | + | . |
Gymnadenia frivaldii | 1 | . | . | . | + | . | 1 | + | . | 1 | 1 | . | 2m | . | 1 | . | . | 1 |
Sphagnum subsecundum | 3 | . | . | . | . | . | . | . | 2a | . | 2a | 1 | + | 2b | . | . | 2b | 3 |
Eriophorum angustifolium | 2b | . | . | . | . | . | . | + | 2a | 2a | . | . | . | 2a | 1 | . | . | . |
Straminergon stramineum | . | + | . | . | . | . | . | . | . | . | 1 | 1 | + | + | . | 2a | . | . |
Philonotis seriata | . | . | 3 | 2a | 3 | . | . | . | . | . | . | 1 | . | . | . | 2a | . | . |
Carex panicea | . | . | + | + | . | . | . | . | . | . | . | . | . | 1 | . | + | . | . |
Vaccinium uliginosum | r | . | . | . | . | . | . | 1 | + | + | . | . | . | . | . | . | . | . |
Allium schoenoprasum | + | + | . | . | . | 1 | . | . | . | . | . | . | . | . | . | . | . | . |
Warnstorfia sarmentosa | . | . | . | . | . | + | 3 | + | . | . | . | . | . | . | . | . | . | . |
Drosera rotundifolia | . | . | . | . | . | . | . | . | . | 1 | . | . | . | . | . | . | . | 2a |
Sphagnum flexuosum | . | . | . | . | . | . | . | . | . | 2a | . | . | . | . | 5 | . | . | . |
Philonotis fontana | . | . | . | . | . | 1 | . | + | . | . | . | . | . | . | . | . | . | . |
Sphagnum palustre s.l. | . | . | . | . | . | . | . | . | 3 | + | . | . | . | . | . | . | . | . |
Comarum palustre | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a | . | . |
Sphagnum auriculatum | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 1 |
Juncus alpinoarticulatus | . | . | . | . | . | . | . | . | . | r | . | . | . | . | . | . | . | . |
Polytrichum commune | r | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Sphagnum platyphyllum | . | . | . | . | . | . | . | . | . | . | . | . | 1 | . | . | . | . | . |
Carex flava | . | . | . | . | . | 2a | . | . | . | . | . | . | . | . | . | . | . | . |
Sphagnum capillifolium | . | . | . | . | . | . | . | . | . | . | . | . | 2b | . | . | . | . | . |
Other species (sorted by frequency) | ||||||||||||||||||
Nardus stricta | 1 | + | 1 | 2a | 2a | + | 2a | + | + | 1 | 2b | 2a | 2a | 1 | 2a | + | 1 | 2b |
Luzula sudetica | + | + | + | 1 | + | + | + | + | + | + | 2a | + | . | + | + | + | . | . |
Festuca rubra | 1 | + | 2m | 1 | + | + | . | + | + | . | . | + | + | . | + | 2m | 1 | + |
Geum coccineum | + | + | + | 2a | 2a | 1 | + | + | . | r | 1 | + | . | . | . | + | . | + |
Deschampsia cespitosa | + | + | . | . | + | . | . | + | + | . | + | + | 1 | + | . | 1 | + | . |
Potentilla erecta | 2a | + | . | . | . | . | . | 1 | 2a | 1 | 2a | . | . | 2a | 2b | 2a | + | 1 |
Ranunculus montanus agg. | + | + | 1 | 1 | 1 | . | . | r | . | . | . | . | + | + | 2a | . | . | . |
Aneura pinguis | . | . | . | + | + | + | + | . | + | + | . | + | . | + | . | . | . | . |
Trifolium pratense | + | + | 1 | . | . | . | . | + | + | . | + | . | . | . | . | . | + | . |
Climacium dendroides | + | + | . | . | . | . | . | 1 | 1 | . | . | . | . | + | . | 1 | + | . |
Scapania irrigua | 1 | . | + | . | 2a | . | . | 2a | + | 1 | . | . | r | . | . | . | . | . |
Plantago gentianoides | . | . | 2a | 2b | . | r | + | . | . | . | + | . | + | . | . | . | . | . |
Anthoxanthum odoratum | + | . | + | . | . | . | . | + | + | . | . | 1 | 1 | . | . | . | . | . |
Succisa pratensis | + | 1 | . | . | . | . | . | 1 | 2a | 1 | . | . | . | . | . | . | . | 2a |
Myosotis scorpioides agg. | . | . | + | . | . | 1 | . | . | . | . | + | . | . | + | . | 2a | + | . |
Juncus thomasii | . | . | . | + | . | . | . | + | . | . | + | . | . | . | . | 1 | . | + |
Juncus articulatus | . | . | + | . | . | 2m | + | . | . | . | . | . | . | + | . | . | . | 1 |
Alchemilla vulgaris agg. | . | . | 1 | + | + | . | . | . | . | . | r | . | . | . | . | 2a | . | . |
Gentianella bulgarica | + | . | . | . | . | . | . | + | + | + | . | + | . | . | . | . | . | . |
Carex bulgarica | . | . | + | + | . | 1 | 1 | . | . | . | . | . | + | . | . | . | . | . |
Cirsium heterotrichum | 1 | 1 | . | . | . | . | . | 2a | 2a | r | . | . | . | . | . | . | . | . |
Sesleria comosa | + | . | . | . | . | . | . | + | + | + | . | + | . | . | . | . | . | . |
Equisetum palustre | . | 1 | . | . | . | . | . | + | + | . | . | . | . | . | . | 1 | . | . |
Molinia caerulea agg. | 1 | + | . | . | . | . | . | . | . | 1 | . | . | . | . | . | . | . | 2a |
Crocus veluchensis | + | + | . | . | . | . | . | 1 | . | . | . | + | . | . | . | . | . | . |
Juncus filiformis | . | 1 | . | . | . | + | . | . | . | . | . | . | . | . | . | 1 | + | . |
Epilobium palustre | . | + | . | . | . | + | . | . | . | + | . | . | . | + | . | . | . | . |
Saxifraga stellaris | . | . | + | + | . | + | . | . | . | . | . | . | . | . | . | . | . | . |
Scapania undulata | . | + | . | + | . | . | 1 | . | . | . | . | . | . | . | . | . | . | . |
Homogyne alpina | . | . | . | . | . | r | . | . | . | . | . | + | + | . | . | . | . | . |
Sanguisorba officinalis | + | . | . | . | . | . | . | + | + | . | . | . | . | . | . | . | . | . |
Salix lapponum | . | + | . | . | . | . | . | 1 | 2a | . | . | . | . | . | . | . | . | . |
Caltha palustris | . | + | . | . | . | + | . | . | . | . | . | . | . | . | . | 1 | . | . |
Scorzoneroides autumnalis | + | . | . | . | . | . | . | . | . | . | . | . | . | + | . | + | . | . |
Luzula luzulina | . | . | . | . | r | . | + | + | . | . | . | . | . | . | . | . | . | . |
Trifolium spadiceum | . | + | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a | 1 | . |
Bruckenthalia spiculifolia | . | . | . | . | . | . | . | . | . | + | . | . | + | . | . | . | . | + |
Ligusticum mutellina | . | . | + | . | . | . | . | . | . | . | . | + | + | . | . | . | . | . |
Vaccinium vitis-idaea | . | . | . | . | . | . | . | . | . | 1 | . | . | . | + | + | . | . | . |
Equisetum fluviatile | . | . | . | . | . | . | . | . | + | . | . | . | . | . | 1 | . | 2m | . |
Chiloscyphus polyanthos | . | . | 1 | . | . | . | . | 1 | . | . | . | + | . | . | . | . | . | . |
Oenanthe silaifolia | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | + | . | . |
Palustriella decipiens | . | . | 2a | 3 | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Scapania paludicola | . | . | . | . | . | . | . | . | . | . | + | 2a | . | . | . | . | . | . |
Dichodontium palustre | . | . | 1 | . | . | 1 | . | . | . | . | . | . | . | . | . | . | . | . |
Pyrola rotundifolia | . | . | . | . | . | . | . | + | + | . | . | . | . | . | . | . | . | . |
Selaginella selaginoides | . | . | . | + | . | . | + | . | . | . | . | . | . | . | . | . | . | . |
Geum rhodopeum | . | . | . | . | . | . | . | . | . | . | . | . | . | 2b | 2a | . | . | . |
Epilobium nutans | . | . | . | . | r | . | . | . | . | . | + | . | . | . | . | . | . | . |
Riccardia multifida | . | . | + | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . |
Angelica pancicii | . | . | . | . | . | + | . | r | . | . | . | . | . | . | . | . | . | . |
Calliergonella cuspidata | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 1 | + |
Holcus lanatus | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | + |
Ranunculus acris | . | + | . | . | . | . | . | . | . | . | . | . | . | . | . | 1 | . | . |
Trifolium repens | . | . | + | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a | . |
Bistorta officinalis | . | + | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . |
Cardamine acris | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a | + | . |
Carex pallescens | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + |
Veronica beccabunga | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | r | . | . |
Atrichum undulatum | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . |
Danthonia decumbens | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + |
Bistorta vivipara | . | . | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . |
Euphrasia hirtella | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . |
Leontodon hispidus | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . |
Gentiana pyrenaica | . | . | . | . | . | . | . | . | . | . | . | . | 2a | . | . | . | . | . |
Dicranum bonjeanii | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . |
Euphrasia officinalis agg. | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . |
Carex leporina | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . |
Juncus conglomeratus | . | . | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . |
Lathyrus pratensis | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . |
Carex viridula | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a |
Chaerophyllum hirsutum | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . |
Blindia acuta | . | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . |
Plagiomnium undulatum | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 2a | . | . |
Trifolium hybridum | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . |
Bartsia alpina | . | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . |
Vicia cracca | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . |
Euphrasia liburnica | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Scirpus sylvaticus | . | . | . | . | . | r | . | . | . | . | . | . | . | . | . | . | . | . |
Primula deorum | . | . | . | . | . | . | . | . | . | . | . | . | 2a | . | . | . | . | . |
Ceratodon purpureus | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . | . |
Pinus peuce | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . | . | . | . |
Prunella vulgaris | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 1 |
Pilosella caespitosa | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + |
Viola palustris | . | . | . | . | . | . | . | . | . | . | 1 | . | . | . | . | . | . | . |
Plagiomnium affine agg. | . | 1 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Palustriella falcata | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . | . |
Salix waldsteiniana | . | r | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Carex umbrosa | + | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Veronica scutellata | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | + | . |
Calliergonella lindbergii | . | . | 1 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Luzula alpinopilosa | . | . | . | . | . | . | . | . | . | . | . | . | + | . | . | . | . | . |
Picea abies | . | . | . | . | . | r | . | . | . | . | . | . | . | . | . | . | . | . |
Cerastium fontanum subsp. vulgare | . | . | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . | . |
Poa annua | . | . | . | . | . | r | . | . | . | . | . | . | . | . | . | . | . | . |
Jacobaea pancicii | . | . | . | + | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
Nomenclatural type: Table
Name giving taxa: Sphagnum contortum, Primula frondosa subsp. exigua (Syn.: P. farinosa subsp. exigua).
Diagnostic species (with respect to other associations within the order): Primula frondosa subsp. exigua, Pinguicula balcanica, Taraxacum sect. Alpina, Cardamine rivularis, Sesleria comosa, Gentianella bulgarica, Trichophorum cespitosum, Carex bulgarica, Cirsium heterotrichum, Soldanella pindicola, Plantago gentianoides, Vaccinium uliginosum, Crocus veluchensis, Carex nigra.
Constant species (100–60%): Eriophorum latifolium, Nardus stricta, Luzula sudetica, Carex echinata, Geum coccineum, Sphagnum contortum, Festuca rubra, Parnassia palustris, Dactylorhiza cordigera, Warnstorfia exannulata, Agrotis canina, Deschampsia cespitosa.
Nomenclatural note: When the name of a syntaxon is formed from the names of two taxa of which only one belongs to the highest of the dominant strata determining the vertical structure, then the name of that taxon appears in the second place (the Code of Phytosociological Nomenclature;
The high-mountain association Sphagno contorti-Primuletum exiguae occurred at significantly higher elevations, while the other two associations did not differ in elevation. The Sphagno warnstorfii-Eriophoretum latifolii association showed the highest water pH, with statistically significant differences compared with the other two associations, while the Geo coccinei-Sphagnetum contorti association exhibited the highest water conductivity (Figure
Box-and-whisker plots showing medians, interquartile ranges, extremes and outliers of elevation (m a. s. l.) and pH, adjusted pH and conductivity (µS.cm-1) for the groundwater for the three associations. The different letters above boxes indicate significant differences. Explanations: 1 – Sphagno contorti-Primuletum exiguae, 2 – Sphagno warnstorfii-Eriophoretum latifolii, 3 – Geo coccinei-Sphagnetum contorti.
At the margin of their southeastern range in the Balkan Peninsula, rich fens may be robustly classified into three associations, one high-mountain association occurring above the treeline in the Balkans, and two occurring at lower elevations. The high-mountain association is characterised by Balkan species that otherwise occur in the Balkan high-mountain fens of the Narthecion scardici alliance (
At lower elevations where high-mountain Balkan fen species do not occur, rich fens with S. warnstorfii (Sphagno warnstorfii-Eriophoretum latifolii) develop from calcareous brown-moss fens, or from S. contortum rich fens. Because such development requires high climate humidity throughout the entire year (
The Geo coccinei-Sphagnetum contorti association, from which the Sphagno warnstorfii-Eriophoretum latifolii may develop if the abovementioned climate conditions are met, is much more widespread in Bulgaria because it only depends on particular groundwater chemistry and does not require such a specific climate (
This delimited cluster was quite small and comprised predominantly vegetation plots with S. warnstorfii. We interpreted it as a specific vegetation type within the Sphagno warnstorfii-Eriophoretum latifolii, but further research on the continental scale is needed. The relevés of this cluster come from the area of the Eastern Carpathians where phosphorus-enriched, nitrogen-limited fens of the Saxifrago-Tomentypnion occur (the Harghita and Covasna regions;
We cannot exclude the possibility that rich fens that have developed from N-limited extremely-rich fens of the Saxifrago-Tomentypnion, but mostly without Ligularia sibirica, may occur in other European areas such as Latvia, Estonia, Finnland, Russia or Swiss Jura Mts (compare distribution of Saxifrago-Tomentypnion in
To conclude, we have presented evidence for distinguishing three well-supported associations of rich fens in Bulgaria, the Geo coccinnei-Sphagnetum contorti, the Sphagno warnstorfii-Eriophoretum latifolii and the Sphagno contorti-Primuletum exiguae ass. nov., with the latter two being reported for Bulgaria for the first time. All these rich-fen associations are rare in SE Europe, occurring here at the margin of their range and acting as irreplaceable refugia of fen biota in this part of the world.
The working data sheets are in Electronic Suppl. material
M.H. and P.H. planned the research and led sampling, data processing and writing. M.H., P.H. I.A., D.S., I.G. and D.D. conducted the field sampling; the last two authors only in Romania. All authors critically revised the manuscript.
This work was supported by the Czech Science Foundation. M.H. was supported by the CEVS (Centre for European Vegetation Syntheses) project (no. 19-28491X), while participation of P.H. and D.D. was supported by the standard grant project (no. 19-01775S) and by the long-term developmental project of the Czech Academy of Sciences (RVO 67985939, support for P.H.). We thank Ţucu (Constantin Goia), Veronika Horsáková, Michal Horsák, Milan Valachovič, and many other friends for logistic support and help in the field. We are indebted to Vítězslav Plášek and Eva Mikulášková for revisions of some bryophyte specimens and Anna Szabó who recommended us some fen sites to visit.
Working species-by-sample matrix (csv file)
Working sample-by-variables matrix and geographical coordinates (csv file)