The floodplain woods of Tuscany: towards a phytosociological synthesis

Matilde Gennai,Fabio Lucchesi,Antonio Gabellini,Michele Giunti,Michele Mugnai,Bruno Foggi,Lorella Dell’Olmo,Daniele Viciani,Francesco Monacci,Roberto Venanzoni

doi:10.3897/pls2021581/01

Abstract

The recent Landscape Plan of Tuscany Region pays particular attention towards the floodplain woods, for their conservation concern, landscape, and historical importance. The floodplain forest vegetation is defined as the natural and semi-natural wood vegetation located close to the rivers and submerged only during exceptional flooding. We gathered 180 both published and unpublished relevés coming from Tuscany and carried out in floodplain woods, where Alnus glutinosa, Fraxinus angustifolia subsp. oxycarpa, Quercus robur, Ulmus minor, Carpinus betulus, Populus nigra, P. alba and Salix alba were dominant, alone or in consociation with each other. On this dataset we performed a multivariate analysis, and the resulting groups were characterized by several points of view: floristic, ecological, chorological, by mean of diagnostic species, with the use of EIV. Moreover, their distribution in Tuscany was better defined. According to our results, six associations were found to be present in Tuscany. Thereby, one new association and three new subassociations were proposed. The syntaxonomic arrangement above the association level was discussed, with particular attention to the Italian Fraxinus angustifolia subsp. oxycarpa-rich communities. Finally, a comparison with the Annex I habitat types (sensu Directive 92/43/EEC) was carried out.

Highlights

Floodplain forests are considered one of the most widespread forest communities in Europe (Schnitler et al 2007) and represent an important biodiversity hotspot (Ward et al 1999; Geilen et al 2004)
We gathered 180 both published and unpublished relevés coming from Tuscany and carried out in floodplain woods, where Alnus glutinosa, Fraxinus angustifolia subsp. oxycarpa, Quercus robur, Ulmus minor, Carpinus betulus, Populus nigra, P. alba and Salix alba were dominant, alone or in consociation with each other
Alluvial forests are widespread across the continent, covering large areas in central and northern Europe, while representing only relic communities in southern Europe and the Mediterranean. They are dominated by deciduous broadleaves: the black alder (Alnus glutinosa (L.) Gartner) in the marshy areas and the English oak (Quercus robur L.) in the typical alluvial plains; in our region we found the elm (Ulmus minor Mill.) and southern ash (Fraxinus angustifolia Vahl subsp. oxycarpa (Willd.) Franco & Rocha Afonso)

Summary

Introduction

Floodplain forests are considered one of the most widespread forest communities in Europe (Schnitler et al 2007) and represent an important biodiversity hotspot (Ward et al 1999; Geilen et al 2004) They are severely endangered ecosystems, threatened by land-use changes. The growing number of invasive alien species such as Robinia pseudoacacia L., Ailanthus altissima (L.) Swingle, Acer negundo L. and Amorpha fruticosa L. represents an additional risk today (Schnitler et al 2007; Lazzaro et al 2020; Viciani et al 2020) For these reasons, the recent landscape plan of the Tuscany Administrative Region identifies the conservation and management of "alluvial soils", as one of the main concerns for conservation (Marson 2016), in order. The plan integrates the three main components of the landscape: aesthetic-perceptive (aesthetic values), ecological (environmental values of the landscape) and structural features (relationships between cultural and natural aspects structured over time)

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