Wild Rice and Alpine Rock Plants Get New IUCN Red List Assessments

Three plants with very different lives — a wild rice hiding in Sri Lankan swamps, a saxifrage clinging to the highest Dolomite peaks, and a rock rose on Sardinian sea cliffs — have just received formal conservation assessments under the categories and criteria of the International Union for Conservation of Nature. The assessments, published in the Italian Botanist as the fifteenth installment of an ongoing series of global and regional Red List evaluations, assign a Vulnerable category to the rhizomatous rice Oryza rhizomatis at the global level, upgrade the Dolomite endemic Saxifraga facchinii to Endangered, and downgrade the Sardinian populations of Helianthemum caput-felis to Near Threatened at the regional Italian level. Together, the three case studies illustrate how modern Red List science combines field surveys, geospatial tools, demographic monitoring and climate projections to translate scattered botanical observations into standardized risk categories.

Oryza rhizomatis, known locally as Uru wee and in English as rhizomatous rice, is a perennial grass endemic to Sri Lanka, where it is restricted to the low-altitude dry zone of the eastern and southwestern parts of the island. Field records place it in only six administrative districts — Puttalam, Anuradhapura, Kurunagala, Hambantota, Monaragala and Ampara — in forests and open tall scrub with grassy clearings, typically in swampy or periodically flooded areas under full sun or partial shade. The dry zone where it grows receives between 850 and 1,900 millimeters of rain each year, and the species depends on the persistence of those wet microhabitats. Unlike cultivated rice, this wild relative propagates both by seed, which can enter dormancy, and vegetatively through underground rhizomes, a growth form that distinguishes it from close relatives in the Oryza officinalis complex.

The new global assessment reveals a species in measurable retreat. Using GeoCAT, the Geospatial Conservation Assessment Tool, the assessors calculated an extent of occurrence of 14,603 square kilometers, down from 20,213 square kilometers two decades earlier, a decline of roughly 28 percent. The area of occupancy, computed on a fixed 2-by-2-kilometer grid, fell from 120 to 76 square kilometers, a 37 percent reduction. Recent field surveys conducted between 2020 and 2022 failed to confirm twelve populations previously reported in Puttalam, Kurunagala, Anuradhapura and Hambantota districts, and observers describe ongoing habitat degradation driven by urbanization and grazing across most localities. On that evidence, the species qualifies as Vulnerable under criterion A2c, which captures an observed decline in area of occupancy, extent of occurrence and habitat quality over the assessment window.

The threats catalogued for the wild rice read like a checklist of pressures on Sri Lanka’s dry-zone landscapes. Housing and road construction consume populations in the Northwestern Province, where some plants grow along roadsides and are disturbed by roadside cleaning. Cattle and goats graze many sites, and elephants were observed browsing populations inside or near forests. Three populations in Puttalam district and one in Anuradhapura district sit near cultivated fields, exposing them to herbicides and pesticides and to the further expansion of agricultural land. The coastal population at Kirinda in Hambantota district was devastated by the 2004 Indian Ocean tsunami, which reduced it to as few as 20 individuals. Finally, because the species depends on swampy or periodically flooded ground, drought and the drying of swamps during the wet season under higher temperatures and reduced precipitation could erode its remaining habitat.

Conservation infrastructure for the wild rice already exists in fragments. Twenty ex situ accessions are stored in the germplasm bank of the International Rice Research Institute and 23 more at the Plant Genetic Resources Center in Peradeniya, Sri Lanka, while the species occurs within Yala, Luhugala and Wilpattu national parks. The first in situ conservation site for wild rice, at Vanathavilluwa in Puttalam district, was established under the Northwestern Province Environmental Statute No. 12 of 1990. The assessors call for research and monitoring to clarify population trends and for new seed collections to broaden the genetic variability held in storage — a notable point for crop scientists, since wild relatives of rice carry genetic diversity that breeders may one day draw upon for traits such as drought tolerance or disease resistance.

Half a world away in latitude but equally exposed, Saxifraga facchinii is a rare perennial hemicryptophyte found only on calcareous and dolomitic rocks of the Italian Dolomites, at elevations of roughly 2,600 to 3,200 meters. It occurs on several massifs — Catinaccio/Rosengarten, Pale di San Martino, Marmolada, Sella, the Sasso Lungo/Langkofel group, Tofane, Conturines and the Odle — but more than half of its occupied habitat lies in small, isolated patches, unambiguously meeting the IUCN definition of severe fragmentation. The plant belongs to high-alpine to nival communities that include endemic companions such as Draba dolomitica, and its most probable seed dispersal strategy is barichory, meaning seeds simply fall close to the parent, limiting the species’ ability to colonize new ground.

The upgraded Endangered category rests on a combination of restricted range, fragmentation and projected climate-driven habitat loss. The assessors calculated an extent of occurrence of 978 square kilometers with QGIS minimum convex hull and an area of occupancy of 196 square kilometers on the 2-by-2-kilometer grid, applying criterion B1ab(iii,iv)+B2ab(iii,iv) because of continuing projected decline in habitat extent and quality and in the number of subpopulations. Climate modeling projects habitat loss to 2070 of an average 75.52 percent under the rcp 4.5 scenario and 87.59 percent under rcp 8.5, with substantial uncertainty ranges. Field evidence already shows the process in motion: subpopulations recorded near the species’ lower elevational limit of about 2,500 meters on the Schlern/Sciliar massif at the start of the twentieth century are now missing, their former sites converted to arid meadows with Sesleria caerulea as expanding low-alpine communities fill in the rocky habitats the saxifrage requires. Additional pressures include ski-area development at high elevations, trampling by hikers and climbers on trails, and collection by rock-garden enthusiasts.

Unlike the Sri Lankan rice, Saxifraga facchinii enjoys no legal protection at international, national or regional levels, although many of its populations grow within Dolomite natural parks such as Paneveggio–Pale di San Martino, Puez Odle, Sciliar–Catinaccio, Fanes Sennes Braies and Dolomiti d’Ampezzo. The assessors recommend a research and monitoring program to illuminate the species’ reproductive biology and population trend, alongside the design of in situ and ex situ conservation measures for possible population reinforcement and assisted colonization — the deliberate movement of populations to sites where they may survive under a changing climate. A specific monitoring program, they note, would help detect emerging threats such as rising temperatures, expanding high-elevation ski resorts or stochastic events before they alter the species’ status. The assessment grew out of a doctoral thesis funded by the Free University of Bozen-Bolzano and took shape at the COST Action 18201 Conserve Plants training school on Red List assessment held in Podgorica in spring 2022, an example of how capacity-building networks feed directly into formal conservation outcomes.

The third assessment shifts the lens from global to regional, examining Helianthemum caput-felis, the cat-head rock rose, in Sardinia. This thermophilous, long-lived half shrub, 35 to 50 centimeters tall, is distributed in disjunct and fragmented populations around the western Mediterranean — the southeastern Iberian Peninsula, the Balearic Islands, Sardinia and northwestern Africa. In Sardinia it is confined to the Sinis Peninsula, where two main populations at Capo Mannu and Su Tingiosu anchor a scatter of smaller groups. The species is entomophilous and mostly self-incompatible, its hermaphrodite flowers lasting only three to four days, and its seeds germinate in autumn at the onset of the rains, with high germination rates after scarification. Globally, the species is categorized as Endangered under criterion E, and it has been listed as Endangered in Europe and Spain, Critically Endangered in Algeria and, until now, in Italy.

The Sardinian picture is unexpectedly brighter. A four-year demographic study across populations in Spain and Sardinia found the global population roughly at equilibrium, and the Sardinian populations show the greatest stability, with a finite growth rate above one, probably because they are structured mainly around large, long-lived individuals. Capo Mannu is in demographic growth and Su Tingiosu stable, apart from losses caused by landslides and collapses of the rocky cliffs. Monitoring spanning more than two decades has detected no continuous decline in extent of occurrence, area of occupancy, habitat quality or mature individuals — both metrics stand at just 16 square kilometers. On that basis the assessors downgraded the regional category to Near Threatened, while adopting the precautionary approach embedded in IUCN guidelines: if the predicted threats materialize, the species’ tiny area of occupancy combined with declining habitat surface would immediately qualify it for Endangered. All Sardinian populations fall within protected areas, including Natura 2000 sites, the Penisola del Sinis – Isola di Mal di Ventre marine protected area and the Montiferru–Sinis regional park, the species is covered by Annex I of the Bern Convention and Annex II of the Habitats Directive, and seeds are banked in European germplasm collections. Successful translocations elsewhere in its range suggest that reintroduction and reinforcement could be widely deployed if local extirpations occur.

Read together, the three assessments demonstrate the machinery of contemporary Red List science at work. Geospatial software converts herbarium records and field waypoints into extent and area of occupancy; fixed grids and criteria A through E standardize how decline, fragmentation and fluctuation are weighed; demographic matrices test whether populations are growing or shrinking; and climate envelopes project where habitat will remain by mid-century. They also show how the same framework can yield opposite trajectories — an upgrade for a climate-squeezed alpine endemic, a downgrade for a Mediterranean shrub whose monitored populations are holding steady — and how categories can change as data improve. For the rhizomatous rice, the Dolomite saxifrage and the Sardinian rock rose alike, the assessments mark not an endpoint but a baseline: the starting point for the monitoring, seed collection and habitat protection that will determine whether the next evaluation records recovery or further decline.

Subject of Research: Global and Regional IUCN Red List Assessments: 15

Article Title: Global and Regional IUCN Red List Assessments: 15

Article References: Orsenigo, S., Calderisi, G., Cogoni, D., Mondoni, A., Nascimbene, J., Rota, F., Sajeevan, T., Wijayasinghe, M., Wellstein, C., & Fenu, G. (2023). Global and Regional IUCN Red List Assessments: 15. Italian Botanist, 15, 177-191. https://doi.org/10.3897/italianbotanist.15.107040

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.15.107040

Keywords: Global, Regional, IUCN, List, Assessments, scientific research