Vascular plant extinction in the continental United States and Canada.

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 han extinguido en nuestra área de estudio desde el asentamiento de los europeos. Siete de estos taxones existen en cultivos, pero se encuentran extintos en vida libre. La mayoría de las extinciones ocurrieron en la parte oeste del área de estudio, aunque este resultado puede reflejar el momento de la exploración botánica en relación con el asentamiento europeo. El 64% de las plantas extintas eran endémicas de un sitio único y muchas tuvieron presencia fuera de los puntos calientes de biodiversidad. Dada la escasez de los censos botánicos en muchas áreas, particularmente previo al asentamiento europeo, la tasa actual de extinción de las plantas vasculares es sin duda mucho más alta de lo que se indica en este estudio.

Essential Oil Content, Composition and Bioactivity of Juniper Species in Wyoming, United States.

The objective of this study was to evaluate variations in leaf essential oil (EO) content and composition of Juniperus species in the Bighorn Mountains {J comimunis L. (common juniper), J. horizontalis Moench. (creeping juniper), and J scopulorum Sarg. (Rocky Mountain juniper)} in Wyoming, USA. The EO was extracted via steam distillation of fresh leaves (needles). The EO composition of the three Juniper species varied widely. Overall, the essential oil content of fresh leaves was 1.0% (0.4-1.8% range in different accessions) in J. communis, 1.3% (1.2 to 1.6% range) in J. horizontalis, and 1.1% (0.7-1.5% range) in J. scopulorln. The EO chemical profile of J. communis was very different from that of the other two species. The concentration of α-pinene in the oil was 67- 80% in J. communis, 2.8-6% in J. horizontalis, and 2.3-13% in J. scopulorun. The concentration of sabinene was 57-61% of the oil of J. horizontalis and 13- 59%. in oil of J. scopulorum, whereas sabinene was either below 1% or not detected in J. communis. The oils of J scopulorm and J horizontalis had higher antioxidant capacity than that of J. communis. The oils of the three junipers did not show significant antimicrobial activity against 10 organisms. The diversity of the essential oil composition of these three junipers may encourage diverse industrial applications of Juniperus leaf essential oil.