Vascular plant extinction in the continental United States and Canada

• Published in: Conservation biology 2021-02, Vol.35 (1), p.360-368
• Main Authors: Knapp, Wesley M., Frances, Anne, Noss, Reed, Naczi, Robert F. C., Weakley, Alan, Gann, George D., Baldwin, Bruce G., Miller, James, McIntyre, Patrick, Mishler, Brent D., Moore, Gerry, Olmstead, Richard G., Strong, Anna, Kennedy, Kathryn, Heidel, Bonnie, Gluesenkamp, Daniel
• Format: Article
• Language: English
• Subjects: Animals; Anthropocene; Biodiversity; Biodiversity hot spots; Biological settlement; Canada; conservación; conservation; Conservation of Natural Resources; Cultivation; Endangered & extinct species; endemismos de sitio único; Extinct plants; Extinct species; Extinction; extinction rate; Extinction, Biological; Flora; Flowers & plants; Genera; Plants; rareza; rarity; Recognition; Research Note; single‐site endemics; Species extinction; Surveys; tasa de extinción; Taxa; Taxonomy; taxonomía; United States; Wildlife conservation
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1111/cobi.13621

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty‐four percent of extinct plants were single‐site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here. Extinción de las Plantas Vasculares en Canadá y los Estados Unidos Continentales Resumen Se espera que las tasas de extinción aumenten durante el Antropoceno. Todavía desconocemos las tasas de extinción actuales de las plantas y muchos animales. Cuantificamos las tasas de extinción de la flora vascular de los Estados Unidos Continentales y Canadá a partir del asentamiento de los europeos. Recopilamos datos sobre especies aparentemente extintas mediante la consulta de bases de datos sobre conservación, búsquedas en la literatura y el escrutinio de la lista resultante con botánicos expertos. Ya que la opinión taxonómica varía ampliamente, desarrollamos un índice de incertidumbre taxonómica (ITU). La ITU abarca desde la A hasta la F, en donde la A indica un reconocimiento taxonómico unánime y la F indica el reconocimiento taxonómico por un sólo autor. La ITU nos permitió evaluar rigurosamente las tasas de extinción. Nuestros datos sugieren que 51 especies y 14 taxones infraespecíficos, que en conjunto representan a 33 familias y a 49 géneros de plantas vasculares, se ha