A novel insight into the remnants of hygrophilous forests and scrubs of the Po Plain biogeographical transition area (Northern Italy)

Abstract

Hygrophilous forests and scrubs are ecotonal habitats providing essential ecosystem services, especially in human-modified landscapes; nevertheless, they are among the most threatened habitats worldwide. A sound knowledge of waterside woody vegetation provides a valuable basis for interventions of renaturation of waterbodies. This paper focuses on peculiar communities that occur in riparian and swamp areas of the Po Plain, a broad ecotonal area between the Mediterranean and Temperate regions. The study allowed the description of six new associations. Moreover, it provides a detailed picture of Dioscoreo communis-Populetum nigrae (Populetalia albae) and Amorpho fruticosae-Salicetum albae (Salicetalia purpureae), an overview of Salicetum triandrae (Salicetalia purpureae) at the national and European level, and an update of the alliance Dioscoreo-Ulmion minoris, which is better characterized, classified in Populetalia albae and enlarged to include five associations of elm-oak-rich forests of the Po Plain lowlands and the Karst. Dioscoreo-Ulmion includes, besides Lamio orvalae-Ulmetum minoris, also Polygonato-Quercetum roboris and three new associations: Vinco minoris-Ulmetum minoris and Salvio glutinosae-Quercetum roboris from Po Plain rivers and the karstic lakeshore Rhamno catharticae-Ulmetum minoris. The new arrangement of Dioscoreo-Ulmion results from an analysis of Po Plain elm-rich forests including stands so far attributed to the critical alliance Alnion incanae; the presence of Querco-Ulmetum minoris in Italy is discussed. Two new associations are attributed to Prunetalia spinosae: Salici eleagni-Juniperetum communis and Ulmo minoris-Paliuretum spinae-christi. Stands from the Rivers Isonzo and Tagliamento referred to Veratro nigri-Fraxinetum excelsioris and to the new association Carici albae-Fraxinetum excelsioris represent the outermost expressions of the Ostryo-Tilion ravine forests extending towards the High Plain. A Salix alba swamp forest, Galio palustris-Salicetum albae, is reported for the first time in Italy and attributed to Alnetea glutinosae.

The floodplain woods of Tuscany: towards a phytosociological synthesis

“…In the syntaxonomic tables, we also indicated the diagnostic species as reported by the original authors of the syntaxa at the association level, and the phi values of the species (when phi> 20) resulting from the Phi analysis. The attribution of species to Alnetea, Phragmito-Magnocaricetea and Alno-Populetea follows Poldini and Sburlino (2018) and Poldini et al (2020).…”

“…The syntaxonomic scheme at higher ranks follows Biondi et al (2014aBiondi et al ( , 2014b and Biondi and Blasi (2015), with the exception of Salici purpureae-Populetea nigrae class, that was replaced by Alno glutinosae-Populetea albae in order to include only forest communities (Mucina et al 2016;Poldini et al 2020).…”

“…We prefer to use Alno glutinosae-Populetea albae, in accordance with some recent Italian literature (e.g. Poldini et al, 2020), in order to include only riparian forest vegetation.…”

The aquatic and wetland vegetation of Lake Doberdò: an analysis for conservation value assessment of a disappearing lake of the Classical Karst (North East Italy)

“…A peculiar Salix alba-wood occurs along the marginal parts of the lake, on hydromorphic soils in areas with a permanently high water table that are frequently and long flooded by regular high water. It is attributed to the swamp association Galio palustris-Salicetum albae (Annex I Habitat (92/43/EEC Directive): 91E0*) recently discussed by Poldini et al (2020). At Doberdò the physiognomy of the community is given by Carex elata, dominant in the herbaceous layer; Amorpha fruticosa often appears in the shrub layer (see Poldini et al 2020).…”

“…The present paper focuses on the herbaceous plant communities, including the aquatic, marsh and meso-hygrophilous vegetation types. In order to provide the full picture of lake-dependent coenoses, the woody communities are briefly summarized, the peculiar scrub and forest types observed at Lake Doberdò being discussed in Poldini et al (2020).…”