Italy’s Wetland Plants: A 70-Year Review Reveals 1,265 Studies and Big Gaps

Italy’s wetland floras have been studied intensively for decades, yet the effort has been uneven, concentrated in a handful of regions and habitats, and dominated by a single research approach: making inventories.

The numbers tell a clear story about when the work was done. The largest share of contributions, 554 papers, appeared in the twenty years between 1980 and 1999, split almost evenly between the 1980s with 276 papers and the 1990s with 278. Research has consistently been carried out on a local or regional basis, and many contributions have come from the same research groups that focused on one area and its neighbouring geographic areas. This clustering of effort means that national coverage has depended heavily on where individual teams happened to work rather than on a coordinated survey strategy.

Thematically, the literature is overwhelmingly descriptive. Floristic and vegetational inventories account for 932 papers, the predominant research theme across all decades. Studies on ecology follow with 241 contributions, and conservation studies with 123. Taxonomy trails far behind with only 42 papers. One encouraging trend the authors note is that conservation studies have increased significantly from 1980 onwards, in parallel with growing general awareness of the role of nature conservation. Because the same paper could be classified under more than one topic, these thematic totals exceed the number of individual contributions.

The habitats studied are just as skewed. Lakes and ponds lead with 389 papers, followed closely by rivers with 352. Bogs account for 261 contributions, temporary wetlands for 133 and saline habitats for 132, while estuarine waters with 40 papers and rice fields with just 14 are barely represented. The balance has shifted over time: although rivers and lakes dominate the entire period, papers on rivers were overtaken by those on bogs in the 1950s, 1960s and 1970s, and only from the 1990s to the present did river studies become the main category, eventually surpassing even those on lakes.

Geographically, the distribution of studies is strikingly lopsided. Toscana leads with 185 papers, followed by Lombardia with 141 and Sicilia with 131. Emilia-Romagna with 121, Lazio with 112 and Veneto with 109 also exceed one hundred contributions each. At the other end of the scale, Molise has only 15 papers, Campania 20, Valle d’Aosta 23 and Basilicata 25. Of the 1,265 contributions, 998 could be mapped to specific areas while the remaining 267 refer to areas too large or generic to locate. The mapped studies fall within 593 geographical areas, well distributed across northern and central Italy and Sicilia, but sparse in the southern part of Piemonte, Campania, Basilicata and northern Puglia.

A few sites have attracted disproportionate attention. The most studied area in the country is Lake Trasimeno, with 27 papers. Other well-investigated localities include the Tiber River with 11 papers, the Valleys of Comacchio with 10, Lake Massaciuccoli with 9 and the Colfiorito swamp with 8. For nearly everywhere else, the authors conclude, there are insufficient data even to attempt diachronic floristic studies, the kind of repeated surveys that would reveal how wetland vegetation has changed through time. Almost all of Italy’s 57 Ramsar sites, wetlands designated as being of international importance, have been investigated by at least one contribution, with 68 papers concerning them. Yet of the 998 mapped contributions, 218 refer to areas without any legal protection, mostly along river courses or within swampy areas.

To compare research effort against habitat availability, the team divided the country into 10 by 10 kilometre grid cells and counted where freshwater habitats occur and where at least one studied locality falls. Many northern regions, including Emilia-Romagna, Friuli Venezia Giulia, Liguria, Lombardia and Piemonte, along with Molise and Sicilia, have more than 80 percent of their cells containing at least one mapped freshwater habitat. The regions with the highest percentages of cells containing at least one studied locality are Umbria at 29.41 percent, Trentino-Alto Adige at 26.71 percent, Toscana at 25.61 percent and Lazio at 24.06 percent. The lowest are Campania at 4.17 percent, Molise at 5.77 percent, Liguria at 12.35 percent, Calabria at 14.52 percent and Basilicata at 14.55 percent, confirming that large parts of the south remain under-investigated relative to their wetland resources.

The scale of what is at stake is considerable. Italy is described as the richest country in wetlands among those of the Mediterranean Basin, counting 69 natural lakes equal to or larger than half a square kilometre, 183 artificial basins larger than one square kilometre, and more than 230 rivers and streams of particular relevance, of which 58 exceed 100 kilometres in length and 75 have average daily discharges greater than 10 cubic metres per second. The country is also the second highest area, after the Iberian Peninsula, in plant species richness in Europe, with a checklist of 9,948 specific and subspecific taxa, including 8,288 native species and 1,660 alien species. The first comprehensive nationwide inventory of aquatic plants identified 279 specific and subspecific taxa, estimated at 88.5 percent of the total European and Mediterranean aquatic taxa. In Sardegna and Sicilia alone, 13,981 wetlands have been inventoried, covering about 645.96 square kilometres, roughly 1.3 percent of those two regions’ territory.

The methodology behind the review was deliberately inclusive of the botanical literature but strict about scope. The starting point was the reference list published by the Italian Botanical Society, supplemented by later reviews and online databases. The team searched Web of Science, Scopus and Google Scholar using Italian and English terms for wetland types combined with terms for Italy, its two large islands and botanical disciplines. Grey literature such as technical reports and academic theses was excluded, as were algae, bryophytes, fungi and palynological studies, national and regional floras, and contributions on large areas that merely include wetlands. Only research specifically aimed at studying wetland higher plants and current vegetation qualified. Study sites that could be identified were georeferenced and overlaid on the network of protected areas, including Natura 2000 sites, Ramsar sites, national and regional parks and nature reserves.

The authors’ conclusion is a call to action rather than a celebration. Italian wetlands are among the most threatened habitats, and in recent years climate change is further worsening the situation by altering the dynamics of perennial humid environments and making temporary ones disappear. Some habitats, like the Tiber river, have been studied more heavily thanks to their proximity to research centres, but entire areas of southern Italy are still under-investigated. Many investigations have remained in the so-called grey literature of theses, internal documents and survey forms, and the pressure to publish in indexed international journals has discouraged local-scale studies, even though data of local interest form the basis of global knowledge on wetlands. The survey points to the need to continue and intensify botanical studies, especially in southern Italy and in temporary wetlands, and to make unpublished data readily accessible through online geographical databases such as the Italian biodiversity databasing and mapping projects. A sign that the situation may already be changing: at this year’s Congress of the Italian Botanical Society, 12 contributions concerned freshwater plants and habitats, and the newly established National Biodiversity Future Center, a network of 48 partners funded by Italy’s National Recovery and Resilience Plan, will fund research on freshwater biodiversity in its first three years of activity to improve current knowledge levels.

Subject of Research: A literature survey of botanical studies on vascular plants in Italian wetlands from 1950 to 2022

Article Title: An analysis of botanical studies of vascular plants from Italian wetlands

Article References: Barone, G., Cirlincione, F., Di Gristina, E., Domina, G., Gianguzzi, L., Mirabile, G., Naselli-Flores, L., Raimondo, F. M., & Venturella, G. (2022). An analysis of botanical studies of vascular plants from Italian wetlands. Italian Botanist, 14, 45-60. https://doi.org/10.3897/italianbotanist.14.95072

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.14.95072

Keywords: wetlands, Italy, vascular plants, botany, floristic inventory, biodiversity, conservation, lakes, rivers, temporary wetlands, literature review, Ramsar sites