Semi-automated assessment for NatureServe subnational conservation status ranks for state floras.

Premise: Conservation status ranks measure the potential risk of extinction for species at global, national, and subnational levels, taking into account rarity, threats, and trends. These assessments are largely incomplete due to funding and resource limitations. Methods: This study addressed this problem by identifying five semi-automated methods to assign provisionary NatureServe subnational conservation status ranks (S-ranks) to state floras. These involved (1) estimation: (1A) calculating the mode S-rank in surrounding states and (1B) assigning an S-rank based on percentage of counties with occurrence records; and (2) calculating criteria and assigning an S-rank based on the NatureServe rank calculator using (2A) a Feature Manipulation Engine (FME) workflow, (2B) NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT), and (2C) ArcGIS. S-ranks were assigned to Tennessee's native vascular flora using each method and evaluated for accuracy against published NatureServe S-ranks, human rankings, and surrounding state S-ranks. Results: ArcGIS was identified as a suitable method for future ranking efforts due to its batch processing capabilities, accessibility, and agreement with NatureServe S-ranks. Therefore, a manual was created on how other states may implement this method to update and complete their S-ranks. Discussion: By using these methods, states can more efficiently achieve comprehensive and current S-ranks, enhancing plant conservation by providing a more complete understanding of subnational extinction risk.