Research Article |
Corresponding author: Emanuele Fanfarillo ( ema.fanfarillo@gmail.com ) Academic editor: Lorenzo Peruzzi
© 2021 Gianmaria Bonari, Tiberio Fiaschi, Emanuele Fanfarillo, Francesco Roma-Marzio, Simona Sarmati, Enrico Banfi, Marco Biagioli, Stefan Zerbe, Claudia Angiolini.
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:
Bonari G, Fiaschi T, Fanfarillo E, Roma-Marzio F, Sarmati S, Banfi E, Biagioli M, Zerbe S, Angiolini C (2021) Remnants of naturalness in a reclaimed land of central Italy. Italian Botanist 11: 9-30. https://doi.org/10.3897/italianbotanist.11.62040
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Wetlands are among the most fragile habitats on Earth and have often undergone major environmental changes. As a study case in this context, the present work aims at increasing the floristic knowledge of a reclaimed land now turned into an agricultural lowland with scarce patches of natural habitats. The study area is named Piana di Rosia, and it is located in southern Tuscany (Italy). The compiled checklist consists of 451 specific and subspecific taxa of vascular plants. The life-form spectrum shows a predominance of hemicryptophytes, followed by therophytes. The chorological spectrum highlights a co-dominance of Euri-Mediterranean and Eurasian species along with many widely distributed species. The checklist includes seven species of conservation concern, three Italian endemics (Crocus etruscus Parl., Polygala vulgaris subsp. valdarnensis (Fiori) Arrigoni, and Scabiosa uniseta Savi), 41 alien species, 21 segetal species, and 11 aquatic macrophytes of which five helophytes and six hydrophytes. This study suggests that irreversible land-use changes in wetlands can lead towards a simplification of the flora. However, despite the deep transformations that the former wetland has undergone, the presence of some aquatic and protected taxa is interesting. From a conservation point of view, the natural value of this agricultural area could be enhanced and its current management partly reconsidered, thus preserving the remnants of naturalness present.
Agroecosystem, biodiversity, botany, checklist, inventory, phytogeography, SAR, survey, wetland
Wetlands are acknowledged to be among the most biologically productive ecosystems (
In the Mediterranean Basin, natural wetland habitats decreased in extension by 10% between 1975 and 2005 (
In Europe, the loss of wetland biodiversity is a consequence of the declining extent and quality of wetland habitats (
This study concerns a lowland known as Piana di Rosia, located a few kilometers southwest of Siena (Tuscany, central Italy). This former wetland turned into an intensive agricultural area in the 19th century. Though, land-use change and human impact led to a substantial loss of the humid habitats, relict elements of naturalness, related to more or less humid environments, are present.
In Tuscany, information at the species level is usually easily available as it is embedded in floristic online databases (i.e., Wikiplantbase #Toscana –
The Piana di Rosia is a lowland plain of central Italy that covers 23.23 km2 and is located about 10 km southwest of Siena (southern Tuscany, 43°14'38"N, 11°15'35"E). The average elevation is 190 m a.s.l., ranging between 180 and 250 m a.s.l. The area lies within the municipality of Sovicille, in the administrative province of Siena, and is surrounded by small villages (Fig.
The study area borders the Special Area of Conservation (SAC) “Montagnola Senese” (IT5190003) along its western side, and the SAC “Alta Val di Merse” (IT519006) along its southwestern side. The Nature Reserve “Alto Merse” is also nearby present (in Suppl. material
The study area is dominated by alluvial and lake deposits. The alluvial deposits occur in the central and southern part and have a mainly gravelly and/or sandy texture. Lake sediments occur along the borders of the study area, at slightly higher elevations. In the eastern part, eluvian-colluvial deposits occur. In the northeastern part, where superficial deposits are missing, marine Pliocene deposits emerge (mudstones and sandstones). An outcrop of Miocene continental breccia (limestone) is present near the village of Malignano (
The bioclimate of the study area can be classified as Oceanic sub-Mediterranean (Temperate sub-Mediterranean macrobioclimate). The thermotype is lower mesotemperate and the ombrotype is upper sub-humid. Regarding the continentality, the climate is weakly semi-continental (
The Piana di Rosia was formerly an ancient wetland reclaimed in the 19th century for agricultural purposes. The plain was neither included in the existing inventory of the marshy areas of Tuscany (
The main land-use types in the study area derive from thematic maps of
We carried out floristic surveys from 2017 to 2019 in all the land-use types, but excluding urban and industrial areas, with the exception of the airport area, that are limited in extension and out of our aim. The investigations were performed in all seasons. The collected specimens are stored in the herbarium SIENA (acronym follows
To highlight chorological novelties, we checked species distribution at the administrative province, region and national levels (
Finally, we calculated a Species-Area Relationship (SAR) strictly based on the extension of the study area according to the formula proposed by
Graphs were drawn using R Studio v. 3.6.0 (
The floristic checklist includes 451 specific and subspecific taxa for the study area (Suppl. material
According to the SAR formula, we obtained -31.4% of taxa compared to the expected value of 654 and -36.5% for native taxa compared to the expected value of 644. On the contrary, concerning alien species, we obtained +45.2% of taxa compared to the expected value of 29. The most represented families are Poaceae (63 taxa), Asteraceae (53), and Fabaceae (40) (Fig.
Overall, we found seven species of conservation concern. One species (Crocus etruscus Parl.) is included in the IUCN Red List of threatened species and in the European Red List of vascular plants, as Near Threatened, in the Tuscan attention list, and in Annex IV of the Habitat Directive (
We found 10 native taxa that are new or confirmed for the administrative province of Siena: Allium rotundum L., Brachypodium phoenicoides (L.) Roem. & Schult., Bromus racemosus L., Dasypyrum villosum (L.) P.Candargy, Eragrostis pilosa subsp. pilosa, Fragaria viridis subsp. viridis, Medicago praecox DC., Persicaria decipiens (R.Br.) K.L.Wilson, Populus canescens (Aiton) Sm., and Spergularia rubra (L.) J.Presl & C. Presl. We found three native taxa with no records in the last century for the administrative province of Siena. These are Allium longispathum Redouté, Bromus commutatus subsp. commutatus, and Persicaria maculosa Gray. Eight alien taxa are new to the administrative province of Siena: Amaranthus hybridus subsp. cruentus (L.) Thell., A. powellii S.Watson, Beta vulgaris L. subsp. vulgaris, Oxalis articulata Savigny, Panicum miliaceum subsp. miliaceum, Parthenocissus quinquefolia (L.) Planch., Sporobolus indicus (L.) R.Br., and Vitis × koberi Ardenghi, Galasso, Banfi & Lastrucci. With regard to Amaranthus hybridus subsp. cruentus (L.) Thell., several historical specimens are present in SIENA, but many of these specimens were collected at the Botanical Garden of Siena with no clear indication as to whether they were cultivated plants or not, whereas others have no locality.
We found 16 rare native taxa that represent the second or third recent record in the administrative province of Siena. They are Brassica nigra (L.) W.D.J.Koch, Conium maculatum subsp. maculatum, Glyceria fluitans (L.) R.Br., Hordeum geniculatum All., H. marinum Huds., Lythrum tribracteatum Salzm. ex Spreng., Orobanche caryophyllacea Sm., O. crenata Forssk., Polygonum arenastrum Boreau, Raphanus raphanistrum subsp. landra (Moretti ex DC.) Bonnier & Layens, Stachys annua subsp. annua, S. palustris L., Thalictrum minus subsp. minus, Tordylium maximum L., Veronica cymbalaria subsp. cymbalaria, and Visnaga daucoides Gaertn.
Of the 41 alien species, 30 are neophytes and 11 are archaeophytes. Neophytes are Actinidia deliciosa (A.Chev.) C.F.Liang & A.R.Ferguson, Ailanthus altissima (Mill.) Swingle, Amaranthus deflexus L., A. hybridus subsp. cruentus, (L.) Thell. A. powellii S.Watson, A. retroflexus L., Artemisia verlotiorum Lamotte, Bidens frondosa L., Crepis sancta subsp. nemausensis (P.Fourn.) Babc., Cuscuta campestris Yunck., Datura stramonium L., Erigeron annuus (L.) Desf., E. bonariensis L., E. canadensis L., E. sumatrensis Retz., Euphorbia maculata L., E. prostrata Aiton, Fagopyrum esculentum Moench, Helianthus tuberosus L., Mirabilis jalapa L., Oxalis articulata Savigny, Parthenocissus quinquefolia (L.) Planch., Paspalum distichum L., Robinia pseudoacacia L., Setaria italica (L.) P.Beauv., Sporobolus indicus (L.) R.Br., Veronica persica Poir., Vitis riparia Michx., Vitis × koberi Ardenghi, Galasso, Banfi & Lastrucci, and Xanthium italicum Moretti. Archaeophytes are Abutilon theophrasti Medik., Arundo donax L., Avena fatua subsp. fatua, Beta vulgaris L. subsp. vulgaris, Galega officinalis L., Hordeum vulgare subsp. vulgare, Isatis tinctoria subsp. tinctoria, Medicago sativa L., Mespilus germanica L., Panicum miliaceum subsp. miliaceum, and Sorghum halepense (L.) Pers. In the study area, the naturalization status for alien species is thus distributed: six taxa are casual, 20 are invasive, and 15 are naturalized.
We found 21 segetal taxa in the study area. Among the segetal species, four are strictly segetal, i.e., strictly related to wheat fields and similar habitats, and they are Alopecurus myosuroides subsp. myosuroides, Bunium bulbocastanum L., Delphinium consolida subsp. consolida, and Legousia speculum-veneris (L.) Chaix subsp. speculum-veneris, the latter being the only segetal species of conservation concern in Europe. The other species are typical for segetal habitats, but commonly occur also in other open and more or less disturbed habitats: Anisantha diandra (Roth) Tutin ex Tzvelev, Avena fatua subsp. fatua, Brassica nigra (L.) W.D.J.Koch, Euphorbia exigua subsp. exigua, E. falcata subsp. falcata, Gladiolus italicus Mill., Lathyrus annuus L., Lysimachia arvensis subsp. arvensis, Matricaria chamomilla L., Muscari comosum (L.) Mill., Myosotis arvensis subsp. arvensis, Orobanche crenata Forssk., Papaver rhoeas subsp. rhoeas, Rapistrum rugosum (L.) All., Sinapis arvensis subsp. arvensis, Veronica arvensis L., and Vicia angustifolia L.
Eleven aquatic vascular plant species were recorded, including five helophytes and six hydrophytes. The helophytes are Carex pendula Huds., Cyperus longus L., Lythrum salicaria L., Phragmites australis (Cav.) Trin. ex Steud., and Schoenoplectus lacustris (L.) Palla, while the hydrophytes are Alisma plantago-aquatica L., Callitriche stagnalis Scop., Glyceria fluitans (L.) R.Br., Lemna minor L., Potamogeton polygonifolius Pourr., and Sparganium neglectum Beeby.
The life-form spectrum shows a predominance of herbaceous taxa, mostly hemicryptophytes (35.9%) and therophytes (30.8%) (Fig.
The chorological spectrum shows a co-dominance Mediterranean (27.1%) and Eurasian (23.5%) elements (Fig.
We studied a reclaimed land of central Italy that is currently an agricultural area. Our floristic surveys revealed the presence of a relatively rich vascular flora in the study area, thanks to the diversity of the habitats present, although most of them occur as small patches. In particular, wetlands and relict woods represent the most relevant elements. Therefore, our results suggest that, despite the conversion to agricultural land, former wetlands host particular species, especially in particular remnant habitats.
The abundance of Poaceae, Asteraceae, and Fabaceae is similar but not consistent with the pattern known for the Italian flora, as the abundance of the first two families in the Italian flora is reversed. The families with fewer species largely follow the trend of the Italian flora (
The high proportion of annual species, mostly linked to non-hygrophilous communities as found by
The chorological spectrum is in line with the life-form spectrum, highlighting a transition between the Mediterranean and Temperate climate. Both, European and Mediterranean species are abundant, with a slight predominance of the former. The high number of widely distributed species is largely due to the occurrence of synanthropic plants (e.g., Alopecurus myosuroides subsp. myosuroides, Chenopodium album subsp. album, and Poa annua L.) and only partially to aquatic plants (e.g., Alisma plantago-aquatica L., Glyceria fluitans (L.) R.Br., and Schoenoplectus lacustris (L.) Palla). Alien species (e.g., Artemisia verlotiorum Lamotte, Amaranthus retroflexus L., and Datura stramonium L.) are abundant due to the high anthropogenic influence. By contrast, the Italian endemics are scarce. Among them, Crocus etruscus Parl. is included in several lists of threatened plant species. This species is a geophyte endemic to Tuscany, Umbria, and Emilia-Romagna. It grows in forests and at forest edges or, less frequently, on grasslands, from 200 to 800 m a.s.l. It flowers between February and April. In our study area, the species was found in deciduous woods with Castanea sativa Mill., Quercus cerris L., Q. pubescens subsp. pubescens, and Q. robur subsp. robur. The populations are not subjected to particular threats, except for a pressure exerted by wild ungulates or human foraging (
The presence of endemics and species of conservation concern, both nationally and locally, is useful to assess the status and quality of a flora and of the environment. As mentioned, in our study area such species are very few. This is predominantly linked to the high human impact but might also be due to the lack of specific substrates, morphology or any other particular environmental features. For example, the Piana di Rosia lacks areas with outcropping rocks. This deficiency is partially compensated by the presence of dry-stone walls, boulders, dirt roads, and road edges. Here, we found characteristic species of outcrops or habitats with low soil formation, such as Cerastium sp. pl., Cymbalaria muralis G.Gaertn., B.Mey. & Scherb., Sedum sp. pl., and Veronica cymbalaria Bodard. Even though such areas are limited and small in size, they host numerous species.
The alien species we found are mostly neophytes and their amount is considerable, with every tenth species being an alien one. The local naturalization status of such taxa mostly matches their status on a regional level, except for a few species that are considered casual or naturalized in the study area, but that are naturalized or invasive in Tuscany, respectively, such as Abutilon theophrasti Medik., Fagopyrum esculentum Moench, Helianthus tuberosus L., Mirabilis jalapa L., and Oxalis articulata Savigny. Despite the relatively high presence of alien species in the Piana di Rosia, not many species behave as invasive when compared with the whole Italian flora (
In the study area, we found new alien species for the administrative province of Siena. Among the most invasive ones, there are Amaranthus hybridus subsp. cruentus (L.) Thell. and A. powellii S.Watson. This is consistent with the invasive character of many species of the genus Amaranthus and with their relevance as agricultural weeds (
The analysis of segetal species revealed that most of the taxa are not of conservation concern in Europe, since all are common and widespread. This is consistent with the fact that agriculture in the area is mostly intensive, and thus there is a lack of the typical species-rich fields common in many traditional agricultural areas of Italy (
This work contributes to the knowledge of the vascular flora of a poorly studied area of southern Tuscany, a former wetland of the previous century. Our results suggest that the land-use changes that occurred in the Piana di Rosia have modified the typical wetland flora and caused a general simplification of the plant species present. Further, the overall number of species and the number of native species present is lower than expected, while the opposite is true for alien species. Despite this, remnants of natural or semi-natural vegetation, like residual woods and shrubs, together with the presence of natural and artificial small water bodies, allow the presence of interesting plant species occurring in relatively undisturbed habitats, such as endemics, relatively rare species, protected species, and hydrophytes. We also found some species that have not been reported in the administrative province of Siena for over a century. These features are typical of “type 2” of the High Nature Value farmlands, i.e., “farmlands with a mosaic of low intensity agriculture and natural and structural elements, such as field margins, hedgerows, stone walls, patches of woodland or scrub, small rivers etc.” (
Although this study fills a gap in the floristic knowledge of southern Tuscany, our data also suggest that the knowledge of southern Tuscany is far from complete and further botanical and ecological investigations are generally needed, also in areas with an alleged scarce environmental value. Accordingly, surveying and inventorying plant biodiversity in current agroecosystems is fundamental for what they have represented in the past, but also for a better application of sustainable management in the future, in the perspective of preserving valuable elements and restore ecosystem functioning and services (
We thank Nicola M.G. Ardenghi and Gabriele Galasso for their help in the identification of some plants, Barbara Anselmi for the help in creating the maps, Ivan Martini for revising the section about geologic aspects, Silvia Cannucci for the help during field surveys, Oretta Muzzi for her help with obtaining poorly accessible literature and the Ampugnano Airport for allowing us to enter the fenced area. We thank Fabrizio Bartolucci, Stefania Biondi and Lorenzo Peruzzi for their comments on the manuscript. G.B. was supported by the Accademia dei Fisiocritici of Siena.
Figures S1–S3 and floristic inventory
Data type: multimedia