Extreme Drought Affects Plant Water Use Even Near Reliable Perennial Springs
Faculty Mentor Information
Dr. Sarah Godsey, Idaho State University
Presentation Date
7-15-2026
Abstract
Although drought limits water availability to ecosystems, perennial springs are thought to reliably sustain streams, riparian ecosystems, and downstream users. However, during droughts, plants near mountain springs in southeastern Idaho located in quartzite parent material transpire less than usual and remain disconnected from the groundwater table. However, it is unknown whether plants behave similarly near springs in limestone. To fill this knowledge gap, sapflow and soil moisture sensors were installed on one limestone spring-adjacent tree and in a nearby soil pit at 20 and 45 cm. Groundwater levels in wells in limestone parent material and outlet streamflow were measured. Accumulated precipitation and snow water equivalent for three drought years (2021, 2022, 2026) were calculated as a percent of normal (1991-2020). Initial results show that 2026 is a more extreme drought year than either 2021 or 2022. Transpiration decreases seasonally with daily mid-afternoon dips. Hillslope and riparian wells were mostly dry whereas stream wells remain wet, with delayed responses compared to plants. Plants are disconnected from groundwater in both limestone and quartzite. However, because the 2026 drought year is more extreme, the full growing season response is required to determine if plant water stress also grows more extreme.
Extreme Drought Affects Plant Water Use Even Near Reliable Perennial Springs
Although drought limits water availability to ecosystems, perennial springs are thought to reliably sustain streams, riparian ecosystems, and downstream users. However, during droughts, plants near mountain springs in southeastern Idaho located in quartzite parent material transpire less than usual and remain disconnected from the groundwater table. However, it is unknown whether plants behave similarly near springs in limestone. To fill this knowledge gap, sapflow and soil moisture sensors were installed on one limestone spring-adjacent tree and in a nearby soil pit at 20 and 45 cm. Groundwater levels in wells in limestone parent material and outlet streamflow were measured. Accumulated precipitation and snow water equivalent for three drought years (2021, 2022, 2026) were calculated as a percent of normal (1991-2020). Initial results show that 2026 is a more extreme drought year than either 2021 or 2022. Transpiration decreases seasonally with daily mid-afternoon dips. Hillslope and riparian wells were mostly dry whereas stream wells remain wet, with delayed responses compared to plants. Plants are disconnected from groundwater in both limestone and quartzite. However, because the 2026 drought year is more extreme, the full growing season response is required to determine if plant water stress also grows more extreme.