THE IMPORTANCE OF TAXONOMY, SPECIES DISCOVERY, AND PRIORITIZATION IN PREVENTING PLANT EXTINCTIONS

Biodiversity conservation is at a challenging juncture in the history of humanity. As we navigate the 6th mass extinction event in Earth’s history (Ceballos et al. 2015), we will need novel methods and ideas to prioritize and prevent as many extinctions as possible, and we will need to identify and invest in areas of scientific shortcomings that limit our knowledge. Among the great challenges we face is our understanding of what species exist, what plant groups need taxonomic investigation to further conservation, and how to prioritize the flora of extinction prevention. This dissertation starts with previously published works that discuss and highlight what is known of plant extinctions at the global and continental levels and the data shortcomings and assumptions that limit knowledge. Among the limitations are describing undescribed species (alpha-level taxonomy) and the need for current taxonomy to inform conservation decisions. Previous work published by Knapp et al. (2021) showed that 64% of all plant extinctions in the continental U.S. and Canada were taxa known from one location, dubbed “single-site endemics”. This led to a chapter on the identification and assessment of plants of One Known Occurrence (OKO), which includes Single-Site Endemics and plants of One Remaining Occurrence, for prioritized conservation action. The next chapter addresses undescribed species by determining the rate of novel species description in two biodiversity hot spots and one cold spot: California, the southeastern United States, and Canada. The last chapter examines the taxonomic concept mappings found in Weakley and the Southern Flora Team’s Flora of the Southeastern United States to see how stable the names we use are across time and to identify and prioritize groups that need investigation. These concepts were combined with NatureServe Global Conservation Assessments to identify plants with conceptually unstable names but with high conservation impact. I hope this dissertation will meaningfully direct conservation action by in situ and ex situ conservation practitioners and academic scientists.