On the basis of literature, and herbarium data and new field research, we provide a diachronic floristic inventory of a small alkaline fen meadow close to the southern border of the Dolomiti Bellunesi National Park (Veneto, N-Italy), whose toponymal is “Torbiera di Lipoi”. Overall, 319 infrageneric taxa were listed. Results indicate that, despite natural reforestation triggered by the abandonment of the traditional management of the fen, most of the fen-related vascular species still occur, including red-listed species, although their populations have probably decreased over time. Moreover, alien species are still a minor component of the flora, occurring in small scattered populations. However, there are signals of vulnerability, and probably the current vascular flora reflects a previous situation in which fen-related habitats were much larger than today. This urgently claims for active maintenance of the small open areas that still exist to counteract extinction debt dynamics.

Biodiversity, diachronic analysis, floristic data, phytogeography, Regional IUCN Red List, Wetlands

Due to land use change and cessation of traditional land use, alkaline fens of the Caricion davallianae Klika, 1934 are among the most endangered ecosystems in Europe (Seer and Schrautzer 2014; DG Environment 2017). These fens are particularly threatened in the southern Alps, where they are rare and small. In particular, fen meadows that developed under low-intensity management are experiencing a decline in plant biodiversity and in rare and endangered plant species due to abandonment of traditional mowing (Billeter et al. 2007; Amici et al. 2015). Lack of mowing triggers natural reforestation, with consequent burial of areas with emerging water and rapid replacement of typical fen species with shrubs and trees. The urgency of stopping the ongoing trend requires targeted management actions and exhaustive floristic inventories in order to provide baseline data for supporting biodiversity conservation.

In this framework, we focused our research on a small alkaline fen meadow close to the southern border of the Dolomiti Bellunesi National Park (Veneto, N-Italy), whose toponymal is “Torbiera di Lipoi”, included in the Natura 2000 network. This site has been the subject of floristic studies and herbarium collections since the 1970s (Buffa and Lasen 2010). Floristic studies started in those years with student theses, such as that of L. Dalle Molle, published by Marcuzzi and Dalle Molle (1976). Later, some references to the “Torbiera di Lipoi” appeared in the floristic catalogue of the Alpi Feltrine (Lasen 1984), while in the same period the results of another thesis were published in a local journal (Ricci 1985). An exhaustive synthesis was published in 1993, which aggregated the floristic data available until that period, but scattered in different sources (Lasen 1993). Floristic research resumed only in 2023 thanks to researchers of the Department of Biological, Geological and Environmental Sciences (BIGEA) of the University of Bologna as part of the Project “Bando Habitat 2020 – Fondazione Cariverona – Progetto di rigenerazione e valorizzazione della Torbiera di Lipoi”.

The specific aim of this work is to provide an updated catalogue of the vascular plants of this small fen and evaluate changes in floristic composition that could be related to abandonment of traditional management.We also aim at qualitatively interpreting ecosystem dynamics and provide some suggestions for future conservation of the vascular flora related to fen-habitats.

The catalogue of the vascular flora of the “Torbiera di Lipoi” includes 319 infrageneric taxa (Suppl. material 1). Seventy-seven taxa were newly found only during the recent floristic survey, while 165 taxa have been confirmed from historical surveys. Seventy-eight taxa were not confirmed. Among these, the historical occurrence of Carex acuta L., C. riparia Curtis, Galium palustre L. subsp. elongatum (C.Presl) Arcang., G. verum L. subsp. wirtgeni (F.W.Schultz) Oborny, and Ranunculus tuberosus Lapeyr. is considered doubtful and probably due to misidentification.

The infrageneric taxa belong to 67 families, seven of which account for about 55% of the total vascular flora (Poaceae 37 taxa, Cyperaceae 32, Asteraceae 20, Lamiaceae 16, Ranunculaceae 16, Rosaceae 16, Fabaceae 14). Compared to the pre-abandonment period, Campanulaceae, Lentibulariaceae, Linaceae, Polygalaceae, and Potamogetonaceae were not found during the recent survey, while new families were found, viz. Caprifoliaceae, Dioscoreacaee, and Onagraceae.

The analysis of life-forms highlights that hemicryptophytes, geophytes, phanerophytes, and therophytes are the most represented, followed by nanophanerophytes, and chamaephytes. Proportions of life forms are relatively constant over time (Fig. 2), even if hydrophytes were not found during the recent survey and phanerophytes tended to increase.

Figure 2. 

Comparison of the life forms composition between the pre-abandonment period and the current situation. Life forms abbreviations: Chamaephytes (Ch); Geophytes (G); Hemicryptophytes (H); Helophytes (He); Hydrophytes (Hy); Nanophanerophytes (NP); Phanerophytes (P); Therophytes (Th).

The chorological spectrum is dominated by Eurasian, European-Caucasic, Eurosiberian, European and Circumboreal species, while Paleotemperate, Subcosmopolite, and south-southeastern European species are less represented. Compared to the pre-abandonment period, the Eurasian, Eurosiberian, and European species clearly decrease (Fig. 3).

Figure 3. 

Comparison of the chorotype composition between the pre-abandonment period and the current situation.

North American species are the main alien taxa and their proportion increased over time. Overall, alien species represent 4.4% of the total flora. Ten are invasive (e.g. Symphyotrichum lanceolatum (Willd.) G.L.Nesom, and Solidago gigantea Aiton), one is naturalized, one casual and two cryptogenetic.

Plantago altissima L. is included in the regional Red List (Buffa et al. 2016) as critically endangered. Seven species are considered vulnerable: Festuca trichophylla (Ducros ex Gaudin) K.Richt., Gentiana pneumonanthe L., Carex lasiocarpa Ehrh., Carex randalpina B.Walln., Dactylorhiza incarnata (L.) Soó, Equisetum fluviatile L., Taraxacum sect. Palustria (H.Lindb.) Dahlst., while Epipactis palustris (L.) Crantz, Menyanthes trifoliata L., and Cladium mariscus (L.) Pohl are near threatened. Two red-listed species recorded in the past were not found, and could be extinct at the local level, i.e. Rosa gallica L., Utricularia minor L.; Potamogeton gramineus L. is considered extinct at the regional level (Buffa et al 2016; Bartolucci et al. 2024) (Table 1).

Natural reforestation, triggered by the abandonment of traditional management of the fen, strongly modified the vegetation of the “Torbiera di Lipoi”, mainly by reducing the surface of the most typical fen-related Natura 2000 habitats and likely causing the local extinction of strictly aquatic taxa, such as Potamogeton gramineus and Utricularia minor. However, our results indicate that most of the fen-related vascular species still occur, including red-listed ones, although their populations have probably decreased over time. Interestingly, this does not appear to be the case for Cladium mariscus and Carex lasiocarpa that are clearly expanding in the fen (personal observation of the authors).

The prevalence of hemicryptophytes in the vascular flora of our study site indicates adaptation to grazing or mowing, typical of open herbaceous environments (Midolo et al. 2024). However, according to our diachronic comparison, the trend is towards a decrease in the number of species with biological forms typical of open environments and an increase in the number of species linked to reforestation, as in the case of geophytes and phanerophytes. This trend is corroborated by historical bibliography. For example, in Ricci (1985), Salix cinerea, Alnus glutinosa (L.) Gaertn., and Quercus robur L. subsp. robur were mentioned as occurring in scattered populations, while currently they are widespread across much of the fen surface. Similarly, other species of trees and shrubs and also herbaceous plants have colonized the site in recent decades, as in the case of Frangula alnus Mill. subsp. alnus and Phragmites australis (Cav.) Trin. ex Steud.

Besides these dynamics, the biogeographic framework of the vascular plant biota is relatively stable, as indicated by the prevalence across time slices of the chorotypes that are typical of fen habitats, as in the case of Eurasian, Eurosibirian, European-Caucasian, and Circumboreal chorotypes that reflect the continental and microthermal character of the cold-temperate zones. The SSE-European chorotype is indicative of the south-eastern Alpine character of the “Torbiera di Lipoi”. However, the steep reduction of fen-habitats during the last 20 years suggests that in the near future the biogeographic structure of this site could also be modified. This view is also corroborated by the increase in the number of alien, mainly north-American, species. Actually, only Veronica persica Poir., Robinia pseudoacacia L., Erigeron annuus (L.) Desf. subsp. annuus, and Oxalis stricta L., were already recorded since the 1990s (Lasen 1993), before abandonment of traditional management. Fortunately, with the exception of Symphyotrichum lanceolatum that forms a relatively large but defined population in the eastern sector of the fen, alien species still occur in small scattered populations. This indicates, on the one hand, that the site still holds a low risk of invasion but, on the other, that its fragility is connected to the fact that any disturbance could immediately trigger an invasion process since the sources of propagules are already on site (Corcos et al. 2020).

This study was carried out in the framework of the project “Bando Habitat 2020 – Fondazione Cariverona – Progetto di rigenerazione e valorizzazione della Torbiera di Lipoi”, funded by Fondazione Cariverona.

We are grateful to Gianni Poloniato, curator of the Herbarium of the Naturalistic Museum Dolomiti Bellunesi (Belluno) for allowing the study on exsiccata from the “Torbiera di Lipoi”. We are also grateful to Carlo Argenti for the suggestions he gave us.