The use of herbarium specimens in evaluating plant extinction risks: some considerations on Sicilian endemics

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Herbarium specimens provide verifiable and citable evidence of the occurrence of plant taxa at a given placeand time. Thus they caΩn be used to identify native ranges, and document which plants are occurring, andwhere, through time. They provide information on rare, extirpated, or extinct species that can no longer befound in nature. Furthermore, they can serve as a means of locating rare or possibly extinct species,recollecting in the area(s) reported on labels. Thus, herbarium specimens can be used as primary sources ofdata to have evidence-based extinction risk assessments.Each extinction risk assessments is an evidence-based hypothesis of the current level of extinction risk of aparticular taxon, to be refined, updated, corrected or refused, if more specimens are discovered, or when thescientific identification of one or more specimens is updated in light of new knowledge.Some data are available from herbarium labels, but often they have to be retrieved ad hoc. Most specimendatabasing projects aim at including metadata, as coarse-level geographical information, latitude andlongitude coordinates (when available), collector name, collection number, date. Finally, the informationabsent in the label but gleaned directly from the specimen or the label is rarely included in major databases.Spatial data is certainly the herbarium-derived information most widely applied to extinction riskassessments.Specimens collected less than 30 years old include often latitude and longitude coordinates, providing a bestestimate of the collection site. Older specimens are less likely to include coordinates, but latitude andlongitude can usually be retrieved from the textual locality information on the specimen. Temporal data areoften present on herbarium specimens in the form of collection dates (even if only year for some olderspecimens) and are usually captured in digitization initiatives. These data are useful for inferring theexistence of a particular plant at a particular period. Population size is rarely documented on herbariumlabels, aside from generalized descriptions e.g., ‘rare’, ‘common’, ‘100 specimens are to be collected’, whichare of use as supporting evidence, but not directly applicable to the criteria.The main problem with Mediterranean collections is the reduced number of data available in order to makestatistical analysis. This happens also with endemics that are usually over-sampled. The combined use oflarge and local collections, both modern and historical, can be of help. In addition, the presence of a taxon ina herbarium collection or in a floristic list rarely provides information about the number of individualsoccurring in the locality. However, herbarium specimens are more reliable in comparison with bibliographicreferences, because their identification can be checked. The study of historical herbarium specimens can givesome indications on their native status, as for Astragalus thermensis Vals., Ipomoea stolonifera (Cirillo)J.F.Gmel., and Centaurea acaulis L. in Sicily and help in distinguishing if they need to be protected or canbe considered aliens.Herbarium studies can be very informative for species with wide distribution that are more easily prone tolocal extinctions, as for instance Anacamptis palustris (Jacq.) R.M.Bateman, Pridgeon & M.W.Chase. Fornarrow endemics, there are more problems. For some taxa, their distribution has decreased since theirdescription, as for Erica sicula Guss. subsp. sicula and Adenostyles alpina subsp. nebrodensis (Wagenitz &I.Müll.) Greuter. For some others, their distribution is incre
Original languageEnglish
Title of host publication114° Congresso della Società Botanica Italiana, VI INTERNATIONAL PLANT SCIENCE CONFERENCE (IPSC), Padova, 4 - 7 September 2019, ABSTRACTS KEYNOTE LECTURES, COMMUNICATIONS, POSTERS
Number of pages1
Publication statusPublished - 2019


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