|Scientific Name:||Saxifraga tombeanensis|
|Species Authority:||Boiss. ex Engl.|
|Red List Category & Criteria:||Endangered B1ab(iii,iv)+2ab(iii,iv) ver 3.1|
|Assessor/s:||Armiraglio, S., Bertolli, A., Comini, B., Ghidotti, B., Prosser, F. & Gentili, R.|
|Reviewer/s:||Rossi, G. & Bilz, M.|
The extent of occurrence (EOO) and area of occupancy (AOO) are under the Endangered category thresholds of 5,000 km² and 500 km² respectively. The global population has a very small distribution range as the species grows only in a restricted region of the Alps under particular ecological conditions: carbonatic and dolomite rocky cliffs between 700 m and 2,150 m elevation.
The species was found in only two locations corresponding to the areas over and under the tree limit. We suspect a future habitat quality reduction due to a change in native species dynamics and a subsequent increasing competition of tree and shrub species. The number of subpopulations in the last 15 years has been decreasing.Climate change expected for the alpine region may also affect the species fitness and its survival.
This plant is endemic to the Italian Alps where it can be found in Lombardia, Veneto, and Trentino Alto-Adige.
It is present in the southeastern Alps, mostly in the eastern Lombardy Pre-Alps and Raethian Alps. It can be found in the Garda Pre-Alps, particularly in the Tremalzo-Caplone-Tombea group and the Cadria-Tofino group, marginally in the Bondone-Stivo-Baldo group. Some populations are also present in the Brescia Pre-Alps (C.ma Caldoline, Sonclino) and in the Southern Rhaetian Alps (Val di Non Alps).
The extent of occurrence, measured by means of a GIS database, is 1,449 km2, while the area of occupancy is 120 km2.
Native:Italy (Italy (mainland))
|Range Map:||Click here to open the map viewer and explore range.|
The subpopulations of Saxifraga tombeanensis Boiss. ex Engler are severely fragmented and the species is rare within its range. The number of subpopulations with a mutual distance of more than 500 m are less than 40. There are no quantitative data about all of the subpopulations. Some studies conducted in the Garda Pre-Alps have estimated the presence of 1,000-1,500 cushions. The estimated population size is about 5,000 mature individuals.
|Habitat and Ecology:||
This is a chasmophytic species (cushion plant) that grows on limestone and dolomitic vertical cliffs. The cushions of this species can be found in rocky soils: rocky edges and longitudinal cracks of rocky walls. In these ecological niches Saxifraga tombeanensis is present along with lithophylous species, such as Potentilla caulescens, Daphne petraea, Physoplexis comosa, Carex firma, Primula spectabilis, and Paederota bonarota. Its altitudinal distribution ranges from 700 m to 2,150 m. The subpopulations growing under 1,600 m of altitude, below the present treeline, show mainly a northern exposure.
This plant has a low degree of seed germination in nature and a low density of individuals within the subpopulations. Currently, a change in native species dynamics due to competitors such as Ostrya carpinifolia, Pinus sylvestris, P. mugo takes place in its habitat and negatively impacts the survival of this species. It is also harvested by collectors and gardeners.
Global warming is another threat to this species. The trend of global warming has regionally been measured by a strong increase of the mean annual temperature in the last 30 years, which has been recorded in the meteorological stations close to the distribution range of the species.
Saxifraga tombeanensis is included in Appendix I of the Bern Convention and in Annex II of the Habitats Directive 43/92/CEE. The plants community where it lives is listed in Annex I of the same Directive (habitat code 8210).
The greater portion of its distribution range is included in protected areas such as the Alto Garda Bresciano Park and in several Sites of European Interest (e.g. SIC: IT2070021-Valvestino, IT2070022-Corno della Marogna, IT3120093-Crinale Pichea- Rocchetta, IT3120094-Alpe di Storo e Bondone, IT3120103-Monte Baldo di Brentonico, IT3120104-Monte Baldo – Cima Valdritta, IT3120116-Monte Malachin, IT3120127-Monti Tremalzo e Tombea, IT3210039-Monte Baldo ovest).
During a LIFE project (LIFE03NAT/IT/000147) an experimental restoration plan of the habitat of Saxifraga tombeanensis was carried out. The LIFE Project promoted a series of investigations to identify the main growth sites of Saxifraga tombeanensis with the aim to monitor their ecological characteristics and the morphological and vegetative conditions of the species.Selective tree and shrub clearings were carried out at medium-altitude sites to increase the amount of light getting to the cushions and to re-establish ecological conditions more favourable to the growth and reproduction of the species. Seeds are stored in seedbanks (Lombardy and Trentino Alto-Adige).
|Citation:||Armiraglio, S., Bertolli, A., Comini, B., Ghidotti, B., Prosser, F. & Gentili, R. 2010. Saxifraga tombeanensis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 09 December 2013.|
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