Wetlands are essential for life on Earth, but at the same time the most threatened environments due to the gradual alterations associated with climate change and human action. The botanical studies on wetland higher plants carried out in Italy from 1950 until today are analysed in this survey. The 1,265 contributions resulting from this study are analysed from a historical, geographical, and content point of view. Most of the scientific contributions were published in the 1980s and 1990s, often by the same research groups and on a local scale. The predominant research theme is the inventory. Most papers are mainly focused on lakes and rivers. The results of this literature survey point to the need to continue and intensify these studies, especially in southern Italy and in temporary wetlands. It is essential to make the huge amount of data resting in drawers or included in scientific reports but not published in scientific journals readily accessible. This could also be achieved through online geographical databases.

Conservation, flora, freshwater ecosystems, Literature review, Trends in botany, vegetation

Wetlands are one of the most important natural habitats providing many significant benefits to the environment and humans (Mahdavi et al. 2018). The Ramsar International Convention was adopted as early as 1971 for their protection. This Convention defined wetlands as “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salty, including areas of marine water the depth of which at low tide does not exceed six meters” (Gardner and Finlayson 2018). Wetlands cover about 6% of the Earth’s surface and include mangroves, peatlands and marshes, rivers and lakes, deltas, floodplains and flooded forests and even coral reefs. A wetland is a generalized concept including internal and coastal areas. It is distributed in every climatic region, ranging from the polar zones to the arid ones (Gokce 2019).

Purification of water, reduction of flood risk, protection of shorelines, conservation of soil and water, filtration of sediment, removal of pollution, as well as aesthetic and recreational values are only some of the benefits associated with wetlands (Grenier et al. 2007; Powers et al. 2012; Ji et al. 2015). Wetlands are also the main habitat for hundreds of plants and animals, including one-third of all species at risk (Ozesmi and Bauer 2002; Reimer 2009; Kingsford et al. 2016). Due to their vital biological and ecological functions, wetlands have been called the “kidneys” of nature (Mitsch and Gosselink 2000) and are important indicators of environmental health (Touzi et al. 2007). Early civilizations were established near rivers, lakes and floodplains (Keddy 2010; Gokce 2019). The Mesopotamian civilization is consensually accepted to have started between the Euphrates and Tigris rivers; the other ancestral civilization, Egypt, commenced in the Nile Valley. The fact that civilization started in these regions is a reflection of how important the aquatic habitat is for biotic diversity. Therefore, wetlands are very critical ecosystems and some of them are the most productive habitats (Gokce 2019).

Despite the number of ecosystem services provided by wetlands, they were widely regarded as undesirable in the past and were frequently drained to be replaced with other types of land use, such as urban space and agriculture (Mitsch and Gosselink 2000; Dechka et al. 2002; Fraser and Keddy 2005; Ji et al. 2015). The reasons for wetland loss and deterioration include excessive use, land degradation, climate change, drought, salinization, eutrophication, pollution, decreased biotic diversity, and invasive exotic species (Mahdavi et al 2018; Gokce 2019; Praleskouskaya and Venanzoni 2021). In recent years, attention has been focused on temporary small ponds as important biodiversity sources (Bagella et al. 2009).

Since wetlands are complex multifunctional systems, they are likely to be the most beneficial if conserved as integrated ecosystems rather than as individual component parts (Gokce 2019). From all this emerges the need to know the distribution of these important environments and to monitor their state of health in order to adopt appropriate management and conservation strategies. Wetlands can also be monitored through the study of the plant component. Wetland vegetation, indeed, plays a basic role in aquatic ecosystem ecology (Lastrucci et al. 2018). In particular, wetlands represent an important factor in providing food and shelter for the aquatic fauna (Carpenter and Lodge 1986). Wetland plants also influence hydrological and sediment processes by regulating water flow, crest stability, and soil formation (Saaltink et al. 2018). Wetland plants are endangered by the same forces that generally threaten these ecosystems, including human activities such as wetland draining or filling, hydrologic alterations, chronic degradation due to nonpoint source pollution, and invasion of exotic species (Cronk and Fennessy 2016; Bolpagni et al. 2018; Cuena-Lombraña et al. 2021). Agriculture, housing, industry and tourism are the main drivers responsible for hydrological alterations (Msofe et al. 2019).

Italy is recognized as one of the prominent hotspots for plant diversity at regional and global scales, hosting a rich and diverse range of ecosystems and habitat types (Pedrotti 1971). This is precisely the case of aquatic habitats, which represent a major portion of the total water surfaces in the Mediterranean region (Bolpagni et al. 2018). All national and local floras also include wetlands, but in this survey, we wanted to analyse the scientific contributions specifically dedicated to wet environments.

The state of knowledge on the plant biodiversity of wetlands in Italy is fragmentary. Pignatti’s (1952–1953) work represents a milestone among the phytosociological monographs of wet areas in Italy. Montanari (1988a, 1988b) published a review of the botanical knowledge of Italian rivers. Corbetta and Pirone (1988) and Pirone and Frattaroli (1988) issued a compendium on the vegetation of rivers and freshwater wetlands of Abruzzo. The flora and vegetation of the watercourses of Sicilia, Calabria, and Basilicata were analysed by Ferro and Di Benedetto (1980), Brullo and Spampinato (1990, 1997), and Ferro and Parisi (2002). Sburlino et al. (2004, 2008) dealt with the aquatic and marshy vegetation of north-eastern Italy. Tomei and Kugler (2005) published a synthesis of the botanical knowledge of the wetlands of Toscana. Venanzoni et al. (2018) reviewed the marshy and wet vegetation described or present in Italy. Ciaschetti et al. (2021) summarized current knowledge on the sedge vegetation of the ‘Major Highlands’ of Abruzzo. Recently, Cuena-Lombraña et al. (2021) published a compendium of research results for the Sardinian wetlands. Hence, the need for a review that would encompass the entire national territory. The 1,152 contributions presented and analysed here seem highly indicative of current knowledge about Italian wetland habitats. A survey going further back in time with respect to the contributions reported in this review would certainly have increased the total number of scientific papers, but would not change, in any meaningful way, the general significance of the research results.

We found 1,265 scientific contributions dealing with higher plants in Italian wetlands, published between 1950 and 2022. The largest number of contributions, 554, was published in the 20 years between 1980 and 1999, 276 of which in the 1980s and 278 in the 1990s (Fig. 1).

Figure 1. 

Number of scientific contributions published per decade from 1950 to today.

Research has always been carried out on a local or regional basis. Many contributions have been published by the same research groups that have focused on one area and on neighbouring geographic areas.

The predominant research theme in all the years considered are floristic and vegetational inventories (932 papers). Studies on ecology, and conservation follow, with 241 and 123 contributions, respectively (Fig. 2). It is interesting to note how the trend of conservation studies has increased significantly from 1980 onwards in parallel with the general awareness of the role of nature conservation. Studies on the topic of taxonomy are always the fewest and only reach 42 papers (Fig. 2).

Figure 2. 

Number of scientific contributions classified per topic per decade from 1950 to today. The totals are higher than the contributions published because the same paper could be classified in more than one topic.

As regards wetland types, the largest number of papers are mainly focused on lakes and ponds (389) and rivers (352); bogs, temporary wetlands, and saline habitats account for 261, 133 and 132, respectively (Fig. 3). Papers on estuarine waters (40) and rice fields (14) are less represented (Fig. 3). Although papers on rivers, together with those on lakes, are the most frequent over the entire period, those on rivers were overcome by those on bogs in the 1950s, 1960s and 1970s. From the ‘90s to the present day, papers on rivers become the main ones, surpassing even those on lakes (Fig. 3).

Figure 3. 

Number of scientific contributions per wetland type. For the definition of wetland types see Materials and methods.

As regards the distribution of studies in the different Italian administrative regions, the greatest number concerns Toscana (185), followed by Lombardia (141) and Sicilia (131) (Fig. 4). Emilia Romagna (121), Lazio (112), and Veneto (109) also exceed 100 papers. Molise (15), Campania (20), Valle D’Aosta (23), and Basilicata (25) are the regions for which the lowest number of papers have been published (Fig. 4).

Figure 4. 

Number of scientific contributions per administrative region of Italy.

As shown in Fig. 5, 998 contributions could be mapped to specific areas; the remaining 267 papers refer to areas that are too large, or generic. The contributions were attributed to 593 geographical areas. These areas are well distributed in northern and central Italy and in Sicilia; the southern part of Piemonte, Campania, Basilicata and the northern part of Puglia record few studies. The most studied area is Lake Trasimeno with 27 papers. Other well investigated areas are the Tiber River (11 papers) and the Valleys of Comacchio (10 papers), Lake Massaciuccoli (9) and the Colfiorito swamp (8). In all other cases there are insufficient data to make diachronic floristic studies.

Figure 5. 

Distribution of scientific contributions for the Italian territory in relation to protected areas.

Almost all of the 57 Ramsar sites recognized in Italy have been investigated with at least one contribution included in the list. There are, in fact, 68 contributions concerning them. Of the 998 mapped contributions, 218 refer to areas without any legal protection. These are mostly areas that fall along the course of rivers or within swampy areas. As shown in Table 1 and Fig. 6, many regions of northern Italy (Emilia Romagna, Friuli Venezia Giulia, Liguria, Lombardia, Piemonte) and Molise and Sicilia have a percentage of cells in which at least one freshwater habitat has been mapped higher than 80%. The regions that show the highest percentages of cells in which falls at least one studied locality are Umbria (29.41%), Trentino Alto Adige (26.71%), Toscana (25.61%), and Lazio (24.06%); those with the lowest percentages are Campania (4.17%), Molise (5.77%), Liguria (12.35%), Calabria (14.52%), and Basilicata (14.55%).

Figure 6. 

Distribution of the 10-km² cells with at least one freshwater habitat mapped (light blue) and of the cells including at least one studied locality (purple).

Italian wetlands are among the most threatened habitats, although many of them have been investigated and several fall within protected areas. In recent years, climate change is further worsening the situation by altering the dynamics of perennial humid environments and making temporary ones disappear (Calhoun et al. 2017). Environmental conservation passes through knowledge. Some habitats, like the Tiber river, have been the subject of a greater number of articles, also thanks to their proximity to research centres, but entire areas in southern Italy are still under-investigated. The results of this review highlight the need to intensify botanical research in Italian wetlands, especially in southern Italy and in protected areas, although the situation is already changing. In this year’s Congress of the Italian Botanical Society, as many as 12 contributions concerned the theme of freshwater plants and habitats (Chiarucci et al. 2022). Certainly, many investigations not considered here have been carried out but have remained in the so called “grey literature” (thesis, internal documents, forms, etc.). In recent years, the need for researchers to publish in indexed international journals has discouraged studies conducted at the local level; however, data of local interest form the basis of global knowledge on wetlands. Publishing the contents of these documents is necessary to make them easily and freely accessible to the scientific community and the general public. This can be helped by biodiversity databasing and mapping projects in Italy such as Wikiplantbase #ItaliA (http://bot.biologia.unipi.it/wpb/italia/index.html), anArchive (http://www.anarchive.it), VegItaly (http://www.vegitaly.it) or LISY (http://www.scienzadellavegetazione.it/sisv/lisy/).

The National Biodiversity Future Center was established last June, funded by the National Recovery and Resilience Plan (NRRP) and including a network of 48 partners. It has the purpose of implementing national scientific research on biodiversity. The freshwater biodiversity theme is one of the most heartfelt. In the first three years of activity, research aimed at studying biodiversity at all levels on freshwater environments in Italy will be funded to improve current knowledge levels.

Basic data on biodiversity contextualized within a local socio-economic framework will sustain future management plans for the exploitation of natural resources that take into account the responsible use of aquatic ecosystems and the protection of the biological heritage associated with them. All over the world, the conservation and responsible use of humid environments can act as a driving force for the sustainable development of these realities (Duim van der and Henkens 2007).

The authors acknowledge the support of NBFC to University of Palermo, funded by the Italian Ministry of University and Research, PNRR, Missione 4 Componente 2, “Dalla ricerca all’impresa”, Investimento 1.4, Project CN00000033.