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Long term changes of the inner-alpine steppe vegetation: the dry grassland communities of the Vinschgau (South Tyrol, Italy) 40–50 years after the first vegetation mapping
expand article infoMaximilian Lübben, Brigitta Erschbamer
‡ University of Innsbruck, Innsbruck, Austria
Open Access

Abstract

Aims: The Vinschgau is the driest inner-alpine valley in the Eastern Alps and harbours a unique steppe vegetation. We studied these dry grassland communities and aimed to answer the following questions: Which plant communities can be found currently? Do the syntaxa described by Braun-Blanquet in the 1960s still prevail in the area? Has there been any change in species composition over the last 40–50 years? Study area: Along an approximately 40 km transect, the south-facing slopes of the Vinschgau valley (South Tyrol, Italy) from Mals to Plaus were investigated. Methods: For the classification, 92 relevés were sampled in 2019 and compared with 76 relevés from the 1960s and ´70s by means of vegetation tables and ordinations (Detrended Correspondence Analysis). Results: Based on our investigation, the majority of dry grassland communities can be classified as Festuco-Caricetum supinae. Three subassociations were defined by the dominant species Stipa capillata, Bothriochloa ischaemum and Stipa pennata agg. The comparison of new and old relevés shows an increase in species from the class Sedo-Scleranthetea (e.g. Trifolium arvense, Erodium cicutarium) and the association Artemisieto-Agropyretum. In addition, ruderal elements (e.g. Erigeron annuus, Convolvulus arvensis) have also migrated into dry grasslands. A shift in the dominance over time can be recognized as well. In particular, Festuca rupicola and to some extent also Stipa capillata, have increased in abundance and frequency. Conclusions: We suggest to include the investigated closed dry grasslands in the alliance Festucion valesiacae. The rank of the character species at association, alliance and order level should be re-analysed. In order to obtain a better syntaxonomic overview of western and eastern alpine dry grassland communities in relation to Eastern European dry grasslands, a comprehensive study is absolutely necessary. Furthermore, long-term vegetation dynamics and vegetation change need to be studied in more detailed future studies.

Taxonomic reference: Fischer et al. (2008).

Syntaxonomic references: Mucina et al. (2016) for syntaxa from alliance to class level; Braun-Blanquet (1961) for associations.

Abbreviations: agg. = aggregate; cf. = confer (means ‘compare’); DCA = Detrended Correspondence Analysis; s. lat. = sensu lato; s. str. = sensu stricto

Keywords

biodiversity, Festuco-Brometea, Festucetalia valesiacae, inner-alpine steppes, syntaxonomy, vegetation change

Introduction

The Eurasian steppe belt is the largest steppe region and stretches from the Amur in the east to the Hungarian basin in the west (Hurka et al. 2019). Generally, the Eurasian steppe vegetation harbours a unique and species-rich flora (Dengler et al. 2012; Wilson et al. 2012) and is a key habitat for several animal species (cf. Calaciura and Spinelli 2008; Zulka et al. 2014), especially for insects such as butterflies (WallisDeVries and van Swaay 2009), as well as wild bees, grasshoppers and beetles (WallisDeVries et al. 2002). At the same time, steppes are highly threatened mainly by land use change, e.g. agricultural intensification or abandonment (Habel et al. 2013; Török et al. 2016). A further impact by the ongoing environmental and climate change can be assumed as well (Janssen et al. 2016; Wesche et al. 2016). In contrast to the Eastern steppes, which depend on macroclimate, the Central European steppe vegetation is primarily determined by special edaphic and microclimatic factors. In Central Europe, hence, xerophytic vegetation often has a small expansion and disjunct distribution. These inherently small-scale dry grasslands can be considered as “primary” dry grasslands. The anthropogenic transformation of the landscape, in particular through deforestation of thermophilic woodlands followed by grazing or mowing, led to an area expansion of these “primary” dry grasslands. These dry grasslands, created by anthropogenic influence, make up a significant proportion of the current area of the steppe vegetation in Europe and can be referred to as “secondary” dry grasslands. The exact distinction between primary and secondary dry grasslands is not always possible, however, and this classification is subject to debate (Pott 1996; Ellenberg and Leuschner 2010; Hurka et al. 2019). Outside the Eurasian steppe belt, therefore, there are only azonal islands of steppe vegetation, for instance in central and southern Germany, in Lower Austria and in the inner-alpine dry valleys in the Central Alps (Hurka et al. 2019). The steppe vegetation in these valleys was defined as ”Inneralpiner Trockengürtel”, i.e. inner-alpine dry belt, by Braun-Blanquet (1961, Figure 1) extending from the Durance valley (France) near the Provence across the Vinschgau (South Tyrol, Italy) northeast to Styria (Austria). These valleys harbour a unique steppe flora. Beside (sub)mediterranean species which occur widely in these dry grasslands, especially Eastern steppe species can reach very far to the west in the inner-alpine dry valleys and often have their western-most occurrences in the region (Braun-Blanquet 1936, 1961; Wagner 1941; Ellenberg and Leuschner 2010; Dengler et al. 2020). The origin and evolution of the extra-zonal steppe vegetation is much discussed (Hurka et al. 2019). A recent study (Kirschner et al. 2020), however, pointed out, that some inner-alpine steppe species are phylogenetically largely independent from their eastern relatives so that these steppes can be seen as a relict steppe vegetation. Within the inner-alpine dry belt, the valleys differ in the strength of the continental climate so that there are extreme and more moderate dry valleys (Figure 1), hence, the flora and plant communities differ between the valleys as well (Braun-Blanquet 1961; Schwabe and Kratochwil 2004). In the driest valley of the Eastern Alps, the Vinschgau, dry grasslands mostly occur along the south-west to south-east facing slopes, the so-called “Vinschgauer Leiten”, over approximately 40 km from Mals to Naturns-Plaus (Braun-Blanquet 1961). In addition to the special climatic conditions (Schenk 1949, 1951), especially the lower precipitation on the south-facing slopes, grazing is a primary factor for the occurrence and distribution of these highly diverse communities (Braun-Blanquet 1961; Strimmer 1968; Ellenberg and Leuschner 2010). The interest of botanists for the unique steppe vegetation in South Tyrol resulted into a number of scientific studies at the beginning of the 20th century (citations in Peer 1980). However, apart from the general syntaxonomic overview of the entire inner-alpine dry vegetation by Braun-Blanquet (1961), which still represents the most comprehensive classification of the inner-alpine xerophytic vegetation so far, and the more recent and more ecologically focused overview by Schwabe and Kratochwil (2004, 2012), there are only few phytosociological studies on a regional scale. Recently, inner-alpine dry grasslands in Switzerland were studied (Dengler et al. 2019, 2020) and new syntaxonomical classifications on the European level for the class Festuco-Brometea were published (Willner et al. 2017, 2019). However, none included data from the Vinschgau.

Figure 1. 

Distribution of the inner-alpine dry valleys (with friendly permission by Angelika Schwabe-Kratochwil, according to Braun-Blanquet (1961), modified by M. Lübben) and the two alliances (Stipo-Poion carniolicae and Stipo-Poion xerophilae) described by Braun-Blanquet (1961, see also Mucina et al. 2016).

In the past, three local scientists were concerned with vegetation mapping and ecophysiological investigations (Strimmer 1968, 1974; Florineth 1973, 1980; Köllemann 1979, 1981), building up the most comprehensive description for the steppe vegetation of Vinschgau. Several other publications were dedicated to selected communities (e.g. Staffler and Karrer 2001; Wilhalm et al. 2008) or floristical research (e.g. Wilhalm 2007; Wilhalm et al. 2007; Zippel and Wilhalm 2009).

Due to the essential impacts on vegetation, such as climate change (Gobiet et al. 2014), land use change (Lüth et al. 2011) and atmospheric nitrogen input (Willner et al. 2019), it is doubtful whether the actual Vinschgau dry grassland communities still correspond to the syntaxa described by Braun-Blanquet (1961) and to the communities outlined by the three local scientists 40 to 50 years ago. Already Schwabe and Kratochwil (2004) have noticed ruderalization trends. Therefore, considerable alterations of the communities may be expected.

In the present study we aimed to repeat the relevés performed in the 1960s and 1970s by the three local authors Strimmer (1968), Florineth (1973) and Köllemann (1979). We visited the sites together with them and they identified quite precisely the localities of their relevés in the field and on their vegetation maps. A total of 76 old relevés of typical dry grasslands were then selected and repeated in 2019.

First, we were interested to check if the character species of the syntaxa described by Braun-Blanquet (1961) are still valid. Second, we compared old and new relevés by means of vegetation tables and ordinations and analysed the species composition qualitatively as well as quantitatively. The following hypotheses were outlined: (i) Species composition changed considerably in the last 40–50 years; (ii) The number of ruderal elements (Schwabe and Kratochwil 2004) further increased; (iii) Succession tendencies towards shrub vegetation are visible.

Study area

Over the approximately 40 km long transect from Mals to Plaus (Figure 2) the valley bottom of the study area slopes down from approximately 1,000 m to 550 m above sea level (Strimmer 1968). Also, the steepness of the slopes increases continuously from west to east. This leads to the fact that dry grasslands in Vinschgau continuously give way to a bush forest (Fraxinus ornus, Quercus pubescens) as well as afforestations by Pinus nigra and Robinia pseudacacia (Köllemann 1979). Precipitation is very low (Schenk 1949, 1951); it amounts to around 500 mm in Schlanders (Figure 3). Geologically, the south-facing slopes belong to the “Austroalpine unit” (”Ostalpin” in German), which consists of various metamorphic rocks such as mica schists and paragneisses. Quartz phyllites, amphibolites, orthogneisses, and marbles also occur (Mair 2010; Keim et al. 2017). The soils consist essentially of sandy clay sediments and typically form pararendzines with predominantly neutral or slightly basic pH (Strimmer 1968; Florineth 1973; Staffler et al. 2003).

In the 1960s and ´70s mostly all of the lower slopes in Vinschgau were used as pastures (Braun-Blanquet 1961; Strimmer 1968). Due to a change in agricultural policy, including the afforestation of dry grassland sites (Strimmer 1968; Feichter and Staffler 1996; Staffler and Karrer 2005, 2009; Wilhalm et al. 2008), the areal extent of dry grasslands has decreased. The remaining dry grassland areas are still used as pastures for goats, sheep and even cattle.

Figure 2. 

The investigated study area in the Vinschgau (South Tyrol, Italy) at the south-facing slopes from Mals and Laatsch to Plaus, spanning a length of approximately 40 km (Source: Office for Geology and Building Materials Testing of the Autonomous Province of Bolzano and ISPRA (big map); Eurostat (https://ec.europa.eu/eurostat/web/gisco/geodata/reference-data/administrative-units-statistical-units) EuroGeographics for the administrative boundaries (small map)).

Figure 3. 

Climate diagram from Schlanders (1981–2010) based on data from the 3PCLIM-project (Source: www.3pclim.eu). The red line shows the monthly mean temperature and the blue line the precipitation. Overall, there is an average temperature of 9.5°C and an annual precipitation rate of approximately 530 mm.

Methods

Field sampling

Together with Dr. Strimmer, Prof. Dr. Florineth and Dr. Köllemann, 76 relevés were selected from their studies, relocated in spring 2019, and new relevés were sampled in June 2019. Since it became apparent during the field inspections that there are currently only a few dry grassland occurrences in Dr. Köllemann’s study area and that these were hardly accessible, only the area between Mals and Staben was investigated. Due to the lack of GPS information, a congruent resurvey was not possible. The old relevés could not be spatially assigned exactly to one plot but to larger areas or slopes, thus, a “one-to-one” comparison of old and new plots was not possible. The comparison, therefore, was more focused on the vegetation type so that all 92 new relevés from June 2019 were compared with the 76 old ones in order to investigate the general changes in the species spectrum. Our relevés were sampled using the same cover scale as the three initial investigators (i.e. Braun-Blanquet 1951) to ensure methodological consistency and to compare the relevés as best as possible. As mentioned above, because of the lack of GPS data for the old relevés, the comparison of old and recent relevés does not have the rank of a permanent plot study. Nevertheless, despite some uncertainties in plot relocation, resurveys are a robust enough method to assess vegetation changes over time (cf. Kopecký and Macek 2015).

Mosses and lichens were not recorded. In the first mapping, plots of 100 m² were used for the Vinschgau dry grasslands (according to Mueller-Dombois and Ellenberg 1974). In this work we decided to use the same plot size in order to be able to compare the plots as well as possible and to minimize uncertainties in plot relocation. In some cases, the size of the plots had to be reduced because of the topography (e.g. rocks, hedges and shrubs, afforestation) and in order to ensure best possible homogeneity. GPS coordinates were recorded from the plot centre by using a Garmin Etrex 10. The elevation (m above sea level) was noted simultaneously to the GPS coordinates. In addition, the upper left and lower right corners (viewed up the slope) of each plot were also marked using a steel plate (10 cm × 10 cm). The inclination (°) was determined with a Suunto PM-5/360 PC clinometer and the exposition (°) with a Recta Type DP 10 compass.

Vegetation classification

The raw table with the relevés from 2019 was sorted iteratively using the frequency of the species as a phytosociological characteristic. Relevés with similar floristic composition form a group which is characterized by character and differential species (Braun-Blanquet 1964; Dierschke et al. 1973; Dierschke 1994). Since all site factors find expression in the floristic composition of the plant community, such table can be interpreted floristically, syndynamically, and synecologically (Tüxen 1970, 1974). More importance was given to the higher cover values of Bothriochloa ischaemum, Stipa capillata and S. pennata agg. which reflect mainly physiognomic and structural aspects, when sorting the table. These species mainly characterize different ecological and physiognomical “formations” of dry grasslands in the study area (Figure 4). Therefore, the term “subassociation” was defined more widely in this work by taking greater account of these physiognomical and structural aspects (cf. Westhoff 1967; Hurka et al. 2019). The sorted relevé table with subdivisions below association level is shown in Suppl. material 1, according to which a synoptic table (Table 1) was compiled (Dierschke 1994). The raw table is provided in Suppl. material 2 and Suppl. material 3. Similarly, an individual relevé table with the entire dataset (new and old relevés) was sorted to highlight the floristic differences between 2019 and the 1960s/70s. Based on this dataset, a synoptic table (Table 2) was created. Species groups with diagnostic value were listed and indicated by D1, D2.... in all tables to characterize variants of the plant communities below the association level.

Statistical analysis

In addition to the vegetation tables, a Detrended Correspondence Analyses (DCA) was performed in R (R Core Team 2020) version 4.0.3 by using the VEGAN package (Oksanen et al. 2020) in order to analyse the relevés quantitatively. To minimize the problem of an unduly high influence of rare species on the results, a downweighting was carried out by using the function ‘decorana ()’ with the value iweigh = 1 (Leyer and Wesche 2008; Dormann and Kühn 2011; Oksanen 2015). The Braun-Blanquet scale was converted into the mean abundance values (r → 0.01, + → 0.5, 1 → 2.5, 2 → 15.0, 3 → 37.5, 4 → 62.5) following Dierschke (1994). For further interpretation of the DCA ordination axes, the environmental parameters altitude, aspect and slope inclination were analysed and fitted via the function ‘envfit ()’ with permutations = 999 (VEGAN package). Only significant parameters were added post hoc on the scatter plot.

Floristical nomenclature and syntaxonomy

The nomenclature of the plant species follows Fischer et al. (2008). If possible, plants were identified at the species or subspecies level. Because of the fact that many species showed only vegetative parts or were in an inadequate condition for proper identification, some (sub)species were grouped into aggregates in case of doubt (marked with ‘agg.’ in the tables). The following aggregates were used: Verbascum chaixii agg. (Verbascum chaixii subsp. chaixii, V. chaixii subsp. austriacum), Thymus praecox agg. (Thymus praecox subsp. praecox, T. praecox subsp. polytrichus), Thymus pulegioides agg. (Thymus pulegioides subsp. pulegioides, T. pulegioides subsp. carniolicus), Hieracium pilosella agg. (Hieracium pilosella s.str., H. pilosella subsp. velutinum), Stipa pennata agg. (Stipa pennata s. str., S. eriocaulis subsp. eriocaulis, S. eriocaulis subsp. austriaca, S. epilosa), Veronica verna agg. (Veronica verna s.str., V. dillenii).

Due to a few floristic peculiarities in the Vinschgau, some taxa should be considered closer: Festuca valesiaca (2n = 2x = 14) and Festuca rupicola (2n = 6x = 42) belong to the Festuca valesiaca aggregate. F. valesiaca s. str. is, in addition to the microscopic sclerenchyma features, characterized vegetatively by hair-thin and darker blue-green, frosted leaves. The leaf of F. rupicola usually has a larger leaf cross-section (typically 0.6–0.7 mm), which can be practiced relatively quickly visually and haptically. Furthermore, it is often characterized by a comparatively warmer shade of green (although a blue-green colour, as is mandatory for F. valesiaca, is common). In the Vinschgau also higher-ploidy forms occur which can differ significantly from these two types in their vegetative characteristics. In addition to the number of chromosomes these characteristics primarily concern height, leaf width, leaf cross section and spikelet dimensions. In dry grasslands of lower and middle locations, the two octoploid species F. bauzanina (s. str.) and Festuca bauzanina subsp. rhaetica occur as well (Thomas Wilhalm, pers. comm.; Kiem 1987; Wilhalm et al. 2006; Fischer et al. 2008). However, these “atypical” Festuca species were not investigated further. In general, the identification of the Festuca species was based on macroscopic and often (by necessity) on mentioned vegetative characteristics and collected herbaria material.

From the Stipa pennata complex four elements occur in South Tyrol: Stipa pennata s. str. (quite common), Stipa eriocaulis (by far the most common species, with subspecies subsp. eriocaulis and subsp. austriaca), S. epilosa (very rare). The taxonomic value of these clades is the subject of current research (Thomas Wilhalm, pers. comm.; Wilhalm et al. 2006). According to Florineth (1973) only Stipa eriocaulis occurs in Vinschgau from the aggregate Stipa pennata. Schwabe and Kratochwil (2004) indicate Stipa austriaca as well as transitional forms to S. eriocaulis. Since an exact species identification within this complex was not always possible without any doubt, in this study the species and subspecies are therefore listed under Stipa pennata agg.

The delimitation between the (sub)species within the genus Thymus is not clear in every case. In our investigation this particularly concerns e.g. the alliance character species Thymus serpyllum subsp. carniolicum (= T. pulegioides subsp. carniolicus) (WFO 2021). Generally, hybrids are also very common in the genus Thymus, so that the identification is quite difficult (Fischer et al. 2008; Jäger 2017). In many cases it was not possible to identify subspecies so that the two aggregates Thymus pulegioides agg. and T. praecox agg. are used in this study.

According to Fischer et al. (2008), Scabiosa columbaria s. str. is missing in South Tyrol and in the Inner Alps. Plants that correspond to S. columbaria in terms of identification or combinations of characteristics are thus to be interpreted here as primary hybrids between S. triandra and S. lucida and listed under S. columbaria s. lat.

Hieracium pilosella s. str. and Hieracium velutinum are included in the Hieracium pilosella agg. (Fischer et al. 2008). In general, this aggregate is very rich in form and includes hybrid populations (Wilhalm et al. 2006). According to Dengler et al. (2019), H. velutinum differs also from Hieracium pilosella s. str. ecologically, as it occurs on much drier sites. In this work the species is listed as Hieracium pilosella agg.

Syntaxonomy and classification were essentially based on Braun-Blanquet (1961), Mucina and Kolbek (1993a) and Schwabe and Kratochwil (2004). The mentioned character species in the Suppl. material 1 and in Table 1 as well as the nomenclature of the associations are based essentially on Braun-Blanquet (1961). The nomenclature of the high rank syntaxa followed Mucina et al. (2016).

Results

Syntaxonomy of the new relevés

Based on the character species Astragalus exscapus, Carex liparocarpos, Festuca rupicola, F. valesiaca, Oxytropis xerophila, Petrorhagia saxifraga, Potentilla pusilla, Pulsatilla montana, Silene otites and Stipa capillata dry grassland communities recorded in 2019 (Table 1 and Suppl. material 1) can be assigned to the order of continental dry grasslands, Festucetalia valesiacae in the Festuco-Brometea class. Furthermore, from the alliance Stipo-Poion xerophilae only the relatively constant Centaurea stoebe can be mentioned. Poa molinerii (= Poa xerophila) occurred only in one relevé. At the association level, the Festuco-Poetum xerophilae and the Festuco-Caricetum supinae were identified.

The Festuco-Poetum xerophilae could be documented in only five relevés from the northwest of the study area, near Laatsch (Figure 2). It extends between approximately 1,000 m and 1,100 m a.s.l. on relatively steep, east to south-east exposed slopes. The association can be characterized by Achillea nobilis and, to a lesser extent, Thesium linophyllon. The species group Anthoxanthum odoratum, Bromus erectus, Pimpinella saxifraga, Potentilla argentea (D1, Table 1) as well as some taller shrubs such as, Prunus spinosa and Rosa sp. distinguished this association from the other investigated dry grasslands. Poa molinerii was not present in this community.

The Festuco-Caricetum supinae (87 relevés) occurred on the south-west to south-facing slopes from Tartsch near Mals approximately to Staben-Plaus (Figure 2) with an elevation range between 560 m and 1,400 m a.s.l. These areas were almost all identified as pastures that are still used or were used in the past, extending on more even areas (e.g. at Laas). The Festuco-Caricetum supinae can be divided into three subassociations (Table 1): with Stipa capillata (stipetosum capillatae), with Bothriochloa ischaemum (bothriochloetosum ischaemi), and with Stipa pennata agg. (stipetosum pennatae). The DCA (Figure 5) clearly shows the correlation of inclination for the stipetosum pennatae and of altitude for the two other associations, particularly for the bothriochloetosum ischaemi. It also highlights ”outlier relevés”, which can be seen as transitional stages between subassociations.

Table 1.

Synoptic table of the dry grassland communities in the Vinschgau (South Tyrol, Italy) with all relevés from 2019. Values are percentage frequencies. Only companion species with frequency > 15% are stated. I = Festuco-Poetum xerophilae (col. 1); II = Festuco-Caricetum supinae; II.1 = subassociation stipetosum capillatae (cols. 2-4); II.2 = subassociation bothriochloetosum ischaemi (cols. 5, 6); II.3 = subassociation stipetosum pennatae (cols. 7, 8). The name giving species Stipa capillata, Bothriochloa ischaemum and Stipa pennata agg. are indicated in bold. Variants (D1–D7, cols 2–8) were identified based on the similarity of the species composition: Veronica verna-variant (cols. 2, 5), typical variant (cols. 3, 6, 8), species-poor variant (col. 4), Melica ciliata-variant (col. 7). Abbreviations: AC = association character species, agg. = aggregate, cf. = confer (means ‘compare’), juv. = juvenile, KC = class character species, OC = order character species, s. lat. = sensu lato, sp. = species, ssp. = subspecies, VC = alliance character species.

Vegetation type I II.1 II.2 II.3
Column number 1 2 3 4 5 6 7 8
Number of relevés 5 12 25 8 13 8 9 12
AC1: Festuco-Poetum xerophilae
Achillea nobilis 100
Thesium linophyllon 80 33 12 31 8
D1
Bromus erectus 60 25 16 8 13 11 8
Pimpinella saxifraga 80 4 8
Prunus spinosa 60 8
Potentilla argentea 40 8 8
Anthoxanthum odoratum 40
AC2: Festuco-Caricetum supinae
Astragalus onobrychis 20 92 84 13 100 88 100 58
Carex supina 67 80 25 100 75 78 33
Achillea tomentosa 67 28 50 77 38 11 25
D2
Artemisia absinthium 75 8 38
Buglossoides incrassata 20 58 4 31
Erodium cicutarium 50 4 13 38
Convolvulus arvensis 50 4 8 13
D3
Veronica verna agg. 20 92 44 63 77 38 11 8
Trifolium arvense 100 75 12 88 85 13 11 25
Trifolium campestre 50 13 77 13 11
Plantago lanceolata 58 8 46 13
Turritis glabra 40 50 12 69 8
D4
Silene nutans 16 13
Plantago media 8 16 13
Carduus nutans 20 20 8
Achillea cf. collina 8 13
Trifolium repens 8
D5
Erigeron annuus 75 13 8
Chondrilla juncea 25 16 50 11 8
Quercus pubescens juv. 38 8
Prunus mahaleb 8 38 8 13
Filago arvensis 20 17 12 50 8 8
D6
Melica ciliata 40 42 8 13 15 13 100
Allium sphaerocephalon 100 25 8 25 23 13 67 8
D7
Scorzonera austriaca 8 25
Ephedra helvetica 17
Telephium imperati 17
Seseli pallasii 38 13 17
Kengia serotina 13 25
VC: Stipo-Poion xerophilae
Centaurea stoebe 80 67 52 100 85 50 44 42
Thymus pulegioides agg. 17 31 11
Verbascum chaixii agg. 4 17
Poa molinerii 13
OC: Festucetalia valesiacae
Potentilla pusilla 100 83 96 75 100 100 100 83
Festuca valesiaca 80 83 84 88 92 88 78 83
Festuca rupicola 80 58 88 100 69 100 89 83
Stipa capillata 80 100 100 100 62 88 44 25
Petrorhagia saxifraga 80 75 36 88 77 75 100 75
Silene otites 100 58 56 75 85 63 56 42
Carex liparocarpos 20 33 32 63 8 13 22 33
Pulsatilla montana 40 8 8 23 8
Astragalus exscapus 8 16 15 13
Oxytropis xerophila 4 25
KC: Festuco-Brometea
Veronica spicata 100 17 16 25 69 38 17
Galium lucidum 100 42 44 25 15 44 58
Stipa pennata agg. 100 33 16 50 8 25 100 100
Artemisia campestris 80 100 92 88 100 88 100 100
Phleum phleoides 100 92 88 88 85 75 78 75
Koeleria macrantha 80 83 84 75 100 50 100 67
Thymus praecox agg. 100 67 96 63 77 100 67 67
Verbascum lychnitis 60 67 76 63 54 63 44 25
Alyssum alyssoides 60 83 56 25 85 50 89 50
Arenaria serpyllifolia 60 83 52 50 92 63 67
Bothriochloa ischaemum 20 75 40 88 100 88 78 50
Stachys recta subsp. recta 60 50 40 13 8 38 78 50
Carex humilis 60 42 16 13 15 50 22 33
Lotus corniculatus 20 42 32 31 8
Astragalus glycyphyllos 25 4
Fumana procumbens 8 44 50 23 75 22 50
Helianthemum nummularium subsp. obscurum 20 24 75 8 13 33 58
Medicago minima 40 42 32 38 23 25 11 17
Clinopodium acinos 20 33 4 62 13 33 17
Companion species
Sempervivum arachnoideum 100 50 56 75 85 88 67 92
Hieracium pilosella agg. 100 50 68 25 54 100 44 50
Teucrium chamaedrys 100 42 56 75 23 13 44 67
Erysimum rhaeticum 60 83 40 13 77 63 44 25
Sempervivum tectorum 40 25 32 63 46 38 78 92
Dianthus sylvestris 80 42 36 25 46 75 44 67
Plantago strictissima 80 58 44 46 63 22
Sedum montanum s. lat. 100 58 12 25 31 25 78 33
Scabiosa columbaria s. lat. 25 36 50 38 38 56 17
Teucrium montanum 20 25 40 23 50 44 42
Berberis vulgaris 60 50 40 15 50 11 33
Chenopodium album 33 24 38 54 13 11 8
Medicago falcata 40 58 28 25 8 17
Juniperus communis 25 28 23 13 33 25
Sedum sexangulare 20 17 12 38 25 17
Lactuca perennis 40 17 12 8 13 22 25
Euphorbia cyparissias 8 8 38 15 13 22 8
Tragopogon dubius 20 33 8 23 22
Carex caryophyllea 20 17 16 25 15
Saponaria ocymoides 8 12 15 33 17
Veronica prostrata 25 4 31
Arabidopsis thaliana 60 8 4 15 13
Anthericum liliago 4 13 15 22 17
Viola cf. kitaibeliana 33 4 15
Rosa cf. micrantha 20 8 8 13 11
Rosa sp. 20 8 4 15 11
Allium lusitanicum 12 13 17
Asplenium septentrionale 40 8 25 13
Fraxinus ornus juv. 13 8 22 17
Phelipanche bohemica 20 17 22
Securigera varia 20 4 15 11
Bromus japonicus 25 15
Robinia pseudacacia juv. 11 25
Poa angustifolia 20 8 4 8
Astragalus vesicarius subsp. pastellianus 11 25
Descurainia sophia 25 8
Echium vulgare 17 8
Torilis arvensis 25 8
Hypericum maculatum 23
Calina acaulis 17 4
Verbascum nigrum 17
Silene vulgaris 20 11
Linaria angustissima 20 8
Trifolium alpestre 20 13
Cuscuta epithymum 40
Vicia tetrasperma 25
Geum montanum 20
Figure 4. 

Idealised scheme of the ecological occurrence of the three subassociations of the Festuco-Caricetum supinae (cf. Strimmer 1974). The bothriochloetosum ischaemi occurs mainly in intensively grazed areas, very often on the foot slopes, especially near the village Mals, and sometimes on terraces as well. The stipetosum pennatae characterize the rockier slopes, rocky pulpits and occurs sometimes on rocky parts within the plain areas. The subassociation stipetosum capillatae mostly occur on deeper soils, often on terraces and form very often dense vegetation layers. (Created by M. Lübben).

Figure 5. 

Ordination (DCA) of the Festuco-Caricetum supinae. Three subassociations are shown, characterized by the dominant species Stipa capillata, Bothriochloa ischaemum, and Stipa pennata agg. Transitions between the subassociations are visible.

Subassociation stipetosum capillatae

The subassociation with Stipa capillata was found on low mountain terraces and lower slopes with deeper soils. The community was grass-rich and very often contained tall herbs (Figure 6). Beside Stipa capillata, a particularly high abundance of Festuca rupicola and F. valesiaca was obvious. The character species of the Festuco-Brometea class, such as Artemisia campestris, Koeleria macrantha and Phleum phleoides, were also frequently present. Three variants were identified: the variant with Veronica verna, a typical variant and a species-poor variant in which the association character species were less frequent. In the Veronica verna-variant Artemisia absinthium, Convolvulus arvensis or Plantago lanceolata and some annuals such as Buglossoides incrassata, Trifolium arvense and Veronica verna itself occurred (D2, D3 in Table 1). The typical variant was mainly characterised by the high abundance of grass species such as Festuca rupicola, F. valesiaca, and Stipa capillata. In few relevés of this variant more mesophilic species such as Achillea cf. collina Trifolium repens and Plantago media occurred. In the species-poor variant almost all character species of the Festuco-Caricetum supinae were lacking. In addition, ruderal species such as Chondrilla juncea, Erigeron annuus and Filago arvensis occurred with high abundance (D5 in Table 1). It has to be mentioned that Bothriochloa ischaemum occurred with higher abundance and frequency in this variant as well (Table 1).

Figure 6. 

Subassociation stipetosum capillatae (Photo: M. Lübben).

Subassociation bothriochloetosum ischaemi

This subassociation dominated on the heavily grazed areas of the terraces and the lowest slopes, especially near Mals. The more open and very low-growing vegetation was dominated by Bothriochloa ischaemum, Festuca valesiaca, Potentilla pusilla and Thymus praecox agg. (Figure 7). Alyssum alyssoides, Arenaria serpyllifolia and Artemisia campestris were also recorded. Overall, the herb layer of this subassociation was open. Even here two variants were identified. The Veronica verna-variant was represented by Trifolium arvense, T. campestre, Veronica verna and to some extent also by Plantago lanceolata, Turritis glabra (D3 in Table 1). Artemisia absinthium, Buglossoides incrassata and Erodium cicutarium (D2 in Table 1) were still present but not very dominant. In the typical variant, almost all species from the Veronica verna-variant were absent or occurred less frequently. Only Festuca rupicola, Fumana procumbens, Hieracium pilosella agg. and Thymus praecox agg. were more frequent. Poa molinerii was present only in this variant.

Figure 7. 

Subassociation bothriochloetosum ischaemi (Photo: M. Lübben).

Subassociation stipetosum pennatae

The subassociation stipetosum pennatae characterized the rockier slopes, which were at great risk of erosion, and on rocky outcrops so that the canopy layer showed more gaps (Figure 8). The highly dominant Stipa pennata agg. separated the community from the other subassociations (Figure 5, Table 1). The character species of the order, i.e. Festuca rupicola, F. valesiaca and Potentilla pusilla were present. Artemisia campestris, Koeleria macrantha, Phleum phleoides, and Thymus praecox agg. were also frequent. Stipa capillata was found a few times and with low cover values. Bothriochloa ischaemum occurred just as frequently, but with barely abundance as well. Two variants were identified: the Melica ciliata-variant and the typical variant. Within the Melica ciliata-variant (D6 in Table 1) Melica ciliata and Allium sphaerocephalon were highly dominant. In the typical variant these two species were missing, and the character species Astragalus onobrychis and Carex supina of the Festuco-Caricetum supinae were significantly less abundant than in the Melica ciliata-variant. In addition, in some relevés of this variant Kengia serotina, Scorzonera austriaca and Seseli pallasii occur (D7 in Table 1).

Figure 8. 

Subassociation stipetosum pennatae (Photo: M. Lübben).

Vegetation change over the last 40–50 years

The comparison of new and old relevés showed a clear vegetation change. Over the last 40–50 years, a large group of species newly immigrated (D1 in Table 2). The following species achieved a higher constancy in the immigrating group: Chenopodium album, Erodium cicutarium, Plantago lanceolata and Trifolium campestre (Table 2, cols. 1–2). Together with these species, a number of sporadically occurring species were also new, such as Astragalus glycyphyllos, Descurainia sophia (Table 2, cols. 1–2), Erigeron annuus (Table 2, cols. 2–4) and Silene nutans (Table 2, col. 3) together with a bunch of species with very low occurrence. Some species such as Arenaria serpyllifolia, Artemisia absinthium, Buglossoides incrassata, Festuca rupicola, Trifolium arvense, Turritis glabra and Veronica verna agg. (D2, Table 2) showed a higher constancy in the new relevés and appeared rarely in the old ones. Among them, F. rupicola with its highest constancy clearly separated the new and old relevés. The species group only present or dominating in the old relevés contained grassland species and a few shrubs (D3, Table 2). The diagnostic species of inner-alpine dry grasslands were found with slightly diverging constancy (D4, Table 2) or with equal constancy (D5, Table 2) in the new and old relevés.

The quantitative analysis of the relevés (DCA ordination) confirmed the discrimination of old and new relevés (Figure 9). The separation basically follows DCA axis 1, reflecting the floristic differences.

Table 2.

Synoptic table of the dry grassland communities in the Vinschgau (South Tyrol, Italy) from 2019 in comparison to the 1960s/´70s. Values are percentage frequencies. The columns 1 to 9 show the different relevé groups based on the similarity of the species composition (2019, cols. 1-5; 1960s/70s, cols. 6-9). Different species groups (D1 – D5) were identified which separate the new and old relevés. The floristical shift over time is illustrated by these groups. In D5 species are stated which do not show a clear change over time in their frequencies. Only species with frequency > 15% are stated in this group. Abbreviations: agg. = aggregate, cf. = confer (means “compare”), juv. = juvenile, s. lat. = sensu lato, sp. = species.

Sampling period 2019 1960/70
Column number 1 2 3 4 5 6 7 8 9
Number of relevés 17 16 19 17 23 15 24 26 11
D1
Camelina microcarpa 6
Lolium perenne 6
Medicago sativa 6
Geum montanum 6
Reseda luteola 6
Silene vulgaris 6 6
Descurainia sophia 18 6
Astragalus glycyphyllos 18 6
Bromus japonicus 12 13
Linaria angustissima 6 6
Papaver dubium 6 6 6
Torilis arvensis 6 6 6
Viola cf. kitaibeliana 29 6 4
Plantago lanceolata 65 19 11
Erodium cicutarium 59 13 5
Trifolium campestre 59 44 6 4
Chenopodium album 47 50 21 13
Arabidopsis thaliana 18 6 5 6 9
Anthericum liliago 6 13 5 18 4
Rosa cf. micrantha 6 11 12 4
Plantago media 6 21 4
Taraxacum laevigatum 6 16 4
Phelipanche bohemica 12 6 9
Poa angustifolia 12 6 4
Asplenium septentrionale 6 18 9
Prunus spinosa 12 9
Lactuca serriola 6 5 12
Erigeron annuus 25 5 18
Quercus pubescens 13 6 4
Sanguisorba minor 13 4
Senecio inaequidens 13 6
Vicia tetrasperma 13
Orobanche artemisiae-campestris 6
Ononis spinosa 6
Salvia pratensis 6 5
Veronica fruticans 5 6 4
Silene nutans 26
Achillea cf. collina 16
Trifolium repens 11
Myosotis stricta 5
Carlina vulgaris 5
Anchusa arvensis 5
Cynoglossum officinale 5
Lonicera xylosteum 5
Cerastium semidecandrum 5
Kengia serotina 24
Viscaria vulgaris 18
Quercus petraea 6
Ulmus minor 6
Carduus defloratus 6
Trifolium alpestre 6 4
Cuscuta epithymum 9
Bromus tectorum 9
Anthoxanthum odoratum 9
Telephium imperati 9
Aster alpinus 4
Ononis natrix 4
D2
Artemisia absinthium 71 6 13 4 9
Buglossoides incrassata 76 9
Turritis glabra 59 38 11 13 8
Chondrilla juncea 18 19 5 35 4 9
Trifolium arvense 82 88 41 22 7 38 12 9
Sedum sexangulare 29 6 21 22 15 9
Veronica verna agg. 76 100 32 18 22 4
Arenaria serpyllifolia 82 75 74 24 39 7
Festuca rupicola 71 69 89 88 91 13 27 36
D3
Saponaria ocymoides 18 6 5 12 17 47 33 4 9
Rosa sp. 6 13 13 60 38 4 9
Oxytropis pilosa 13 4
Onosma helvetica subsp. tridentata 13 13
Asparagus officinalis 7 13
Orobanche gracilis 7 9
Veronica teucrium 7
Phelipanche arenaria 8
Cirsium sp. 4
Clinopodium alpinum 4
Medicago lupulina 4
D4
Stipa pennata agg. 24 38 82 74 73 8 35 27
Alyssum alyssoides 82 69 42 29 87 47 29 15 36
Achillea tomentosa 76 63 21 29 17 53 54 19 55
Berberis vulgaris 35 6 53 6 52 93 79 4 9
Juniperus communis 24 6 32 39 80 92 12 9
Hieracium pilosella agg. 65 25 79 29 87 73 92 81 9
Dianthus sylvestris 47 31 37 41 74 80 83 81 36
Plantago strictissima 65 13 53 52 67 88 92 64
Teucrium montanum 29 13 42 24 48 80 88 62
Thymus praecox agg. 71 75 100 59 91 87 75 88 82
Stipa capillata 82 81 100 59 65 80 83 88 82
Bothriochloa ischaemum 71 94 42 71 57 93 92 81 64
Centaurea stoebe 88 75 47 47 57 87 92 88 73
D5
Artemisia campestris 94 100 95 88 96 100 96 85 100
Potentilla pusilla 88 88 95 94 96 93 83 96 100
Festuca valesiaca 82 88 95 71 87 73 100 96 100
Astragalus onobrychis 82 69 89 59 78 100 79 85 82
Phleum phleoides 94 94 79 82 74 73 79 69 64
Sempervivum arachnoideum 71 69 58 71 87 80 96 65 36
Koeleria macrantha 88 88 68 100 70 80 75 46 36
Petrorhagia saxifraga 71 88 47 76 65 100 83 62 45
Silene otites 71 75 42 47 78 93 88 50 27
Carex supina 71 69 74 47 65 33 50 50 64
Erysimum rhaeticum 88 50 32 24 57 80 67 23 18
Carex humilis 35 13 26 24 35 67 58 85 36
Verbascum lychnitis 59 63 89 35 48 53 25 8 27
Sempervivum tectorum 35 31 16 88 70 93 33 12 18
Teucrium chamaedrys 41 38 47 53 65 73 50 4 18
Galium lucidum 29 31 26 24 74 67 58 15 27
Scabiosa columbaria s. lat. 47 25 26 41 30 53 75 38
Fumana procumbens 18 38 37 53 35 73 54 27
Stachys recta subsp. recta 29 25 47 47 48 73 38 4 9
Veronica spicata 41 38 11 18 39 20 29 46 45
Sedum montanum s. lat. 53 13 11 41 61 60 33 12
Helianthemum nummularium subsp. obscurum 6 25 11 65 30 73 50 15 9
Medicago falcata 53 13 32 6 13 27 46 31 36
Allium sphaerocephalon 24 25 29 43 40 33 8 18
Lotus corniculatus 53 19 21 6 9 13 50 27
Carex liparocarpos 35 38 26 24 22 31 36
Clinopodium acinos 41 31 5 18 17 40 33 4 18
Melica ciliata 35 19 24 39 40 17 8 18
Medicago minima 29 31 37 29 17 13 9
Tragopogon dubius 29 19 18 4 27 25 8 18
Bromus erectus 29 13 11 6 17 33 17 9
Thesium linophyllon 41 13 11 22 7 17 4 9
Carex caryophyllea 29 19 11 6 4 31 18
Astragalus exscapus 6 13 16 9 4 38 9
Euphorbia cyparissias 12 13 11 12 17 13 17
Filago arvensis 12 19 11 18 9 13 8 9
Carduus nutans 12 26 7 33 4 9
Lactuca perennis 6 13 5 24 26 13 4
Verbascum nigrum 6 6 42 27
Galium verum 6 6 5 27 25 8 9
Thymus pulegioides agg. 24 13 4 13 13 12
Allium lusitanicum 6 11 6 9 27 13 4
Pulsatilla montana 12 13 11 13 15
Pimpinella saxifraga 12 5 13 21 8
Seseli pallasii 6 24 4 20 13 9
Calina acaulis 12 5 8 19 18
Oxytropis xerophila 11 4 13 19 9
Astragalus vesicarius subsp. pastellianus 6 13 13 21 4
Convolvulus arvensis 35 6 9 7 4 9
Prunus mahaleb 19 11 9 17
Securigera varia 6 6 5 9 7 17
Veronica prostrata 24 13 5 4 4 9
Potentilla argentea 6 13 7 4 4 18
Scorzonera austriaca 6 12 9 27
Fraxinus ornus juv. 6 18 9 9
Robinia pseudacacia 18 4 7 4 9
Lappula squarrosa 6 16 6 4
Achillea nobilis 6 17 9
Echium vulgare 18 9
Figure 9. 

Ordination (DCA) of the old relevés (1960s / ´70s) and new relevés (2019).

Discussion

Validity of Braun-Blanquet’s (1961) syntaxonomy

Following Braun-Blanquet (1961), our relevés from 2019 were clearly included in the order Festucetalia valesiacae (class Festuco-Brometea). The alliance affiliation (Stipo-Poion xerophilae) was less justifiable, because only one character species – Centaurea stoebe – connected the relevés to this alliance. Even if we consider the order character species Festuca rupicola (cf. Mucina and Kolbek 1993a) as a character species for the alliance Stipo-Poion xerophilae, doubts on the validity of the Stipo-Poion xerophilae may be raised. Dengler et al. (2019) defined it as “rocky grassland alliance”. In our study, Poa xerophila (valid species name = Poa molinerii) was recorded in only one relevé. Therefore, we suggest to skip this alliance for most of Vinschgau dry grasslands and to classify them as Festucion valesiacae, similarly to Mucina et al. (2016) and Dengler et al. (2019, 2020). These authors outlined the Eastern European Festucion valesiacae as “non rocky grassland of the Swiss inner-alpine valley” and we highly agree to use this definition also for the investigated Vinschgau’ dry grasslands.

On the association level, we were able to identify two associations (Festuco-Poetum xerophilae and Festuco-Caricetum supinae). According to Braun-Blanquet (1936, 1961), the Festuco-Poetum xerophilae holds an intermediate position between the Koelerio-Poetum xerophilae from the Engadin (Switzerland), which has less xerophytes, and the Festuco-Caricetum supinae. In our investigation, we have a very small database for the Festuco-Poetum xerophilae with only five relevés. Nevertheless, the community is clearly separated by the character species Achillea nobilis and Thesium linophyllon from the Festuco-Caricetum supinae. Braun-Blanquet (1961) described two subassociations for the Festuco-Poetum xerophilae: Erysimum rhaeticum-subassociation and Carex humilis-subassociation. In addition, in the Carex humilis-subassociation two variants were mentioned by Braun-Blanquet (1961): one with Pulsatilla montana and one with Bromus erectus. Both species were recorded also in the 2019 relevés. However, discrimination of variants is by no means justifiable with only five relevés. Due to the unique occurrence of Astragalus onobrychis, the absence of Achillea tomentosa and Carex supina, the relevés are negatively separated from the Festuco-Caricetum supinae (cf. Schwabe and Kratochwil 2004). However, for a precise validation of this association more relevés are needed.

The Festuco-Caricetum supinae was well represented (87 relevés). The association is well justified by the character species. This holds also for the subassociations, based on the dominance of Bothriochloa ischaemum, Stipa capillata and Stipa pennata agg. Nevertheless, as our investigation points out, the three subassociations were floristically closely related and showed transitions. A mosaic distribution of different dry grassland ”fragments” and fluent transitions of dry grassland communities in Vinschgau were already mentioned by Strimmer (1968, 1974) so that the subassociations in this study should not be considered as “strictly” delimited units. Furthermore, it has to be mentioned that Braun-Blanquet (1961) did not describe a plant community with Stipa pennata for the Vinschgau (cf. Schwabe and Kratochwil 2004). Finally, there were still remaining doubts about the affiliation of some relevés (Table 1, col. 8; Suppl. material 1, relevé numbers 87–92) to the association Festuco-Caricetum supinae. In these relevés character species of this association had a very low frequency (AC2, Table 1). To some extent, these relevés are related to the Stipo capillatae-Seselietum variae (cf. Schwabe and Kratochwil 2004) via Scorzonera austriaca, Ephedra helvetica, Telephium imperati and Seseli pallasii (= S. varium var. levigatum) (D7, Table 1). Most of these relevés come from Staben, at the eastern end of the investigated dry grassland transect. The border between the Festuco-Caricetum supinae and Stipo capillatae-Seselietum variae was set by Braun-Blanquet (1961) near Schlanders (cf. Schwabe and Kratochwil 2004). Further investigations have to prove whether the Stipo capillatae-Seselietum variae still occurs in Vinschgau.

On the whole, a more precise determination of some species on the subspecies level could perhaps lead to a more exact delimitation of the associations, subassociations and variants. A comprehensive phytosociological study of the entire inner-alpine steppe vegetation is definitely needed to gain a better syntaxonomical overview and classification in the context of western and eastern dry grassland communities (cf. Mucina et al. 2016).

Changes of species composition after 40–50 years

Over the last 40–50 years, considerable changes in species composition were recognized. The abundance and constancy of Stipa capillata and – to a weaker extent – of Stipa pennata agg. increased, while that of Bothriochloa ischaemum slightly decreased. The most impressive increase was shown by Festuca rupicola. These changes of the character species have to be interpreted with caution. Especially for Festuca rupicola, determination problems in the past cannot be excluded. According to our own observation, F. rupicola inhabits more mesophilic and deeper soils, while F. valesiaca grows dominantly on shallower and drier soils. The different requirements of the two species were already mentioned by Hroudová-Pučelíková (1972) and Florineth (1980). Braun-Blanquet (1961) found F. ovina subsp. sulcata (= F. rupicola) in the Vinschgau only a few times with a low frequency and mainly in the Festuco-Poetum xerophilae (Braun-Blanquet 1961; Kiem 1987).

Besides these uncertain changes, ruderalisation trends, mentioned already by Schwabe and Kratochwil (2004) seem to continue. An increase of annuals (e.g. Arenaria serpyllifolia, Veronica verna) and ruderal species (e.g. Artemisia absinthium, Convolvulus arvensis, Erigeron annuus) was found in our study sites similar to studies in Switzerland (Dengler et al. 2019). Some relevés show a relationship to the ruderal fringe community of the Artemisieto-Agropyretum, so immigration of species from this community towards dry grasslands can be assumed. The Artemisieto-Agropyretum is also floristically very close to the Festuco-Brometea (Kielhauser 1954; Braun-Blanquet 1961; Mucina 1993; Mucina and Kolbek 1993a). The occurrence of some ruderal species (e.g. Artemisia absinthium) may thereby also be related to former land use. Thus, these species can also be considered as indicators of land use change over time.

We also recognized that species from the Sedo-Scleranthetea class (e.g. Erodium cicutarium, Trifolium campestre; D1, Table 2) have immigrated to dry grasslands or increased their abundance. In general, the Festuco-Brometea and Sedo-Scleranthetea classes are floristically strongly related to each other. Several species are common in associations of the order Festucetalia valesiacae as well as in the order Sedo-Scleranthetalia (cf. Braun-Blanquet 1955, 1961; Korneck 1975; Mucina and Kolbek 1993b) such as Allium lusitanicum, Alyssum alyssoides, Sedum album, Sempervivum arachnoideum and S. tectorum.

Ecological factors and anthropogenic influence

According to our investigation the three subassociations of the Festuco-Caricetum supinae generally inhabit different parts in the Vinschgau. The subassociation stipetosum pennatae occurs on rockier and usually steeper areas, while the bothriochloetosum ischaemi stocks on heavily grazed pastures and the stipetosum capillatae grows mainly on deeper soils (Figure 4). We only analyzed the correlation of altitude, aspect and slope inclination with the floristic variation among subassociations. Despite the significance of inclination and altitude, these two environmental parameters cannot entirely explain the occurrence of these subassociations. The DCA (Figure 5) clearly shows the correlation of inclination for the stipetosum pennatae, which confirms our observation. However, there are sufficient reasons to assume that there is some other causal relationship behind the significancy of altitude: the bothriochloetosum ischaemi subassociation essentially characterizes the heavily grazed areas. These occur coincidentally more often near Mals (Figure 2), situated in the higher-altitude Vinschgau; i.e. the parameter altitude is probably a “pseudo-link”, the different species compositions of the subassociation being more explained by the grazing intensity than by altitude. Considering this and taking into account that Vinschgau dry grasslands are also an anthropo-zoogenic habitat, management and especially grazing intensity seem to be more important in this case (cf. Braun-Blanquet 1961; Florineth 1973; Strimmer 1974; Köllemann 1981).

It is known that, in addition to ecological factors, changes in management, i.e. over- or undergrazing respectively abandonment of use, strongly influence species composition and community changes in steppe vegetation (Walter and Breckle 1994; Dúbravková and Hajnalová 2012; Korotchenko and Peregrym 2012; Rachkovskaya and Bragina 2012) and inner-alpine dry grasslands (Strimmer 1968, 1974; Florineth 1973; Köllemann 1981; Schwabe and Kratochwil 2004; Boch et al. 2019; Nota et al. 2021). Schwabe and Kratochwil (2012) mentioned that the succession processes in the inner-alpine dry valleys (primarily bush encroachment) take place very slowly. According to our own observation, shrubs (i.e. Berberis vulgaris, Juniperus communis, Ligustrum vulgare) grow mainly in the fringe of pastures and in rocky parts. Especially on areas and slopes with a tall and dense vegetation layer, presumably due to less grazing, shrubs and sometimes even seedlings of tree species (e.g. Fraxinus ornus, Quercus pubescens) appear. Clonally growing species such as Hippophae rhamnoides or Prunus spinosa, which often occur at the edge of the grasslands, may easily invade the grasslands. This could be observed even at small scale (e.g. near fences) especially where grazing intensity was obviously reduced. In addition, the lack of litter removal and lower soil disturbance as a consequence of lower grazing intensity or abandonment affect the floristic composition of dry grasslands in the long term (Ruprecht 2012). There is also evidence that Stipa capillata increased as a consequence of lower grazing intensity in dry grasslands and steppes (Strimmer 1968, 1974; Florineth 1973; Walter and Breckle 1994). According to our own observations and former investigations (Braun-Blanquet 1961; Strimmer 1968) Festuca valesiaca is very grazing tolerant. We found F. valesiaca more dominant in intensively grazed sites than F. rupicola, so that the latter seems to be slightly less tolerant against grazing. To what extent the three subassociations could be seen as different stages of succession, needs to be investigated. Additionally, the influence of other environmental factors such as temperature, precipitation, nutrient availability, etc. on the floristic composition needs to be studied in future. Furthermore, natural variations in cover values between years (Strimmer 1968, 1974; Gigon 1997), can be relatively high in dry grasslands, and, in contrast, vegetation changes in the long term should be analysed to disentangle the processes of land use change and climate change.

Conclusion

Our investigation shows that current dry grassland communities in the Vinschgau can be identified mainly as the Festuco-Caricetum supinae (order Festucetalia valesiacae). We suggest to include the investigated dry grasslands to the alliance Festucion valesiacae. Although the presented classification is sufficiently justified, the delimitation of the associations and subassociations still needs further discussion. Likewise, the rank of the character species at association, alliance and order level should be re-analysed. A comprehensive study is definitely needed not only to gain a better syntaxonomical overview of western and eastern alpine dry grassland communities but also to evaluate their relation to Eastern European dry grasslands. Especially, relevés from different years and over the whole season of one year are necessary for a more precise classification of the inner-alpine steppe vegetation, to be able to estimate the fluctuations in abundance between years. In addition, a more precise identification of some (sub)species could lead to a more exact delimitation on association-, subassociation- and variant level. The current classification and delimitation of dry grassland communities of the class Festuco-Brometea is neither uniform nor free of contradictions (cf. Mahn 1986; Mucina and Kolbek 1993a; Oberdorfer and Korneck 1993; Dierschke 1997; Ellenberg and Leuschner 2010; Willner et al. 2017, 2019) and needs a revision. Many questions also remain regarding the vegetation dynamics. Our data indicate that Vinschgau dry grasslands have changed floristically over time. In particular, the more mesophilous Festuca rupicola has increased its frequency and abundance. Stipa capillata also shows a positive trend over time. This floristic shift seems to be related to a lower grazing intensity. However, further studies are necessary to obtain a more detailed picture of dry grasslands in Vinschgau and their dynamics. In view of environmental and climate change, interdisciplinary approaches seem promising to obtain more comprehensive knowledge about dry grassland communities and their dynamics in general.

Author contributions

M.L. performed the fieldwork, did the statistical analysis, and wrote the first draft of the manuscript. B.E. supervised the work and improved the drafts of the manuscript.

Acknowledgements

We would like to thank Dr. Thomas Wilhalm (Nature Museum, Bolzano) for his floristic support, Dr. Strimmer, Prof. Dr. Florineth and Dr. Köllemann for their support and information about their study in the Vinschgau, the Department of Botany (University of Innsbruck) for the financial support and the editors as well as the anonymous reviewers for their helpful comments.

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E-mail and ORCID

  • Maximilian Lübben (Corresponding author, m.luebben@posteo.de)
  • Brigitta Erschbamer (Brigitta.Erschbamer@uibk.ac.at)

Supplementary material