Evaluating plant biodiversity measurements and exotic species detection in National Resources Inventory Sampling protocols using examples from the Northern Great Plains of the USA

Native plant biodiversity loss and exotic species invasions are threatening the ability of many ecosystems to maintain key functions and processes. We currently lack detailed plant biodiversity data at a national scale with which to make management decisions and recommendations based on current conservation challenges. We collected plant biodiversity and exotic species richness data from 4 sites in the Northern Great Plains using the modified Whittaker (MW) and Natural Resources Inventory (NRI) methods to evaluate any major differences between indicators generated from these methods and offer recommendations based on findings. Our data indicated that the NRI protocols underestimated both total plant species richness and exotic species richness compared with the MW approach. More importantly, however, results show that biodiversity indicators from the two methods showed similar trends. Increasing time spent on making species richness measurements and implementing a more systematic approach to detecting species within a plot could improve biodiversity inventory and monitoring efforts in NRI while also providing a link between existing long-term data and any new information collected. These adjustments would ultimately help those interested in adopting NRI methods and using plant biodiversity data to increase the amount and quality of information collected.