Droughts are disproportionately impacting global dryland regions where ecosystem health and function are tightly coupled to moisture availability. Drought severity is commonly estimated using algorithms such as the standardized precipitation-evapotranspiration index (SPEI), which can estimate climatic water balance impacts at various hydrologic scales by varying computational length. However, the performance of these metrics as indicators of soil moisture dynamics at ecologically relevant scales, across soil depths, and in consideration of broader scale ecohydrological processes, requires more attention. In this study, we tested components of climatic water balance, including SPEI and SPEI computation lengths, to recreate multi-decadal and periodic soil-moisture patterns across soil profiles at 866 sites in the western United States. Modeling results show that SPEI calculated over the prior 12-months was the most predictive computation length and could recreate changes in moisture availability within the soil profile over longer periods of time and for annual recharge of deeper soil moisture stores. SPEI was slightly less successful with recreating spring surface-soil moisture availability, which is key to dryland ecosystems dominated by winter precipitation. Meteorological drought indices like SPEI are intended to be convenient and generalized indicators of meteorological water deficit. However, the inconsistent ability of SPEI to recreate ecologically relevant patterns of soil moisture at regional scales suggests that process-based models, and the larger data requirements they involve, remain an important tool for dryland ecohydrology.

Amphibians are a group of animals facing especially severe declines due to many factors including climate change and a common pathogen, the amphibian chytrid fungus. To make informed decisions about amphibians, wildlife managers need to identify species facing the greatest threats and the actions that will most effectively minimize impacts of those threats. Although some amphibian species are relatively well-studied, for most, data to inform management decisions are lacking. Therefore, tools to assist managers must be applicable to amphibian species across a range of data availability and susceptibility to climate change and other threats. In this project, researchers will determine which amphibians in the North Central region of the United States are at the greatest risk from the anticipated effects of climate change and other threats, such as disease. They will develop a decision framework for weighing tradeoffs among potential management actions and the anticipated impacts of those actions using both a data-deficient species and a species that is relatively data-rich, the Boreal Toad. This project will then use long-term monitoring information to develop a web application to guide management decisions for Boreal Toads, which are susceptible to amphibian chytrid fungus, likely to be affected by climate change, and are a species of concern for several states in the region. By coordinating with wildlife managers early in the development process, researchers will incorporate feedback from those who will actually use the products of this research and evaluate the effects of potential actions on amphibian populations. Thus, the results of this research will equip managers to make the most informed decisions for amphibian conservation across the North Central region of the United States.