Updating conservation priorities over 111 years of species observations.

Observations of species occurrences are often used to inform spatial prioritizations for the effective use of limited conservation resources. Additional species observations have the potential to change where a conservation group plans to invest. But by how much? How different would conservation priorities be if planners updated current observations with the information they will have next year?, We sought to address these questions using a 111-year data set that reflects commonly used collection and prioritization practices. We quantify changes in the ranking of Tennessee watersheds brought on by annual additions of species observations made between 1900 and 2010. We ranked watersheds by their complementary contribution to overall species richness. We examine the sensitivity of our results to the number of watersheds prioritized., We expected the effect of new observations to diminish as the data set grew, and we found this to be the case. Importantly, however, additional observations may continue to significantly change conservation priorities in the future if current data collection trends continue., We found that, overall, additional observations can greatly affect priorities and that this result is sensitive to the number of watersheds ranked. Thus, the extent of planning activities moderates the effect of including additional data., Synthesis and applications. Long-term, opportunistically collected data of species locations are commonly used in conservation planning. We find that when using such data, additional species observations significantly affect subsequent priorities. This effect is most pronounced when data are sparse. As such, data collection should be a focus of very early conservation actions in new areas. Even in well-studied areas, however, additional observations may continue to change spatial priorities into the future, and so while data collection can decrease in well-studied areas, it should continue at a lower intensity. Our methods could also be used to determine the balance of data collection and conservation action in a new location. [ABSTRACT FROM AUTHOR]