Non Technical Summary
It should not be surprising that plants that can absorb more water will be more abundant in water limited areas like the western US. Yet, we rarely know how much water different species absorb because it is difficult to measure. This research will use new experimental techniques to directly measure water uptake by species common to the western US. We can use this information to understand how much species grow, which species can coexist, and how species will respond to climate change. This information can help ranchers select management approaches. For example, will grass growth increase or decrease over time? How much will grass growth respond to shrub management in the future? Conservationists can use this information to find locations where rare species are likely to succeed in the future. Land managers can use this information to select species that are likely to succeed and can meet management goals whether those are for productivity, diversity, carbon sequestion, or fire control.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	1020	20%
102	0210	1070	20%
102	0720	1020	10%
102	0790	1070	10%
121	0790	1070	30%
206	0790	1070	10%

Knowledge Area
206 - Basic Plant Biology; 102 - Soil, Plant, Water, Nutrient Relationships; 121 - Management of Range Resources;

Subject Of Investigation
0110 - Soil; 0210 - Water resources; 0720 - Pinyon-juniper; 0790 - Rangelands, other;

Field Of Science
1070 - Ecology; 1020 - Physiology;

Goals / Objectives
We have four main goals in this research.1. Measure active root distributions for common species at sites in Nevada, Utah, and Montana. Sites were selected to complement existing data and capture the full range of sagebrush ecosystems in the western US. Sampling will be performed spring 2025, 2026, and 2027.2. Estimate water uptake by each species over time at each site. The soil water flow model Hydrus 1D will be used to simulate water uptake. Modeling will begin summer 2024 and continue as new data is collected.3. Compare water uptake to plant growth and water content on the landscape. Vegetation surveys will be conducted during each sampling campaign.4. Simulate plant growth across the western US in response to climate and shrub management over the next century. Model development will begin summer 2024 and continue as data is collected.

Project Methods
Hydrologic tracer (deuterium oxide) will be injected to target depths in replicate plots three times for each of two growing seasons at each site. This will provide a description of vertical active root distributions across the growing season. These active root distributions will be used to parameterize soil water flow models (Hydrus 1D and STEPPWAT2) to estimate water uptake over time.