Trait Data for Utah’s Central Basin and Range Wetland Plants

Wetlands are important refuges in Utah’s Central Basin and Range ecoregion (“Central Basin”), providing water and food in an otherwise harsh and arid landscape, but unfortunately data on their current condition and functions are lacking. As part of our wetland surveys, the Utah Geological Survey has been collecting plant community data which can be used to further our understanding of the state of Central Basin wetlands. Different plant species have different values for functions such as wildlife habitat, water quality improvement, and flood containment. They also have different sensitivities to disturbances such as cattle grazing, nutrient inputs, and soil disturbance. By assigning scores to plant species related to their functional or disturbance-sensitivity traits and then calculating site-wide scores for those traits, we can make inferences about a wetland’s value for certain functions or what stressors the wetland is currently experiencing. This study focuses on 1) compiling data to assign scores to common Central Basin species for different traits and 2) testing if nutrient tolerance wetland scores appear to align with nutrient input data collected in the field. We found several databases that contributed most of the information for the data compilation component. Between 31% and 61% of plant species documented in the Central Basin were assigned trait values for most of our focal traits. We also found that sites rated as having high water quality stress in field data had higher nutrient tolerance scores derived from plant trait data than sites with lower water quality stress. Further analysis is needed to determine whether water quality stressors are driving plant community composition towards nutrient-tolerant species or whether other factors influence both water quality stress and plant communities. INTRODUCTION Wetlands are important refuges in Utah’s Central Basin and Range ecoregion (“Central Basin”), providing water and food in an otherwise harsh and arid landscape (figure 1). Unfortunately, Central Basin wetlands face many threats, including declining groundwater and surface water levels due to a long history of diversions and groundwater pumping, disturbance from livestock and feral animals, impaired source water, and development pressure along the Wasatch Front. Overarching these threats is the fact that basic information on Utah’s Central Basin wetlands is lacking, which creates gaps in our understanding of their current conditions and functionality. The Utah Geological Survey (UGS) has been working to address these data gaps by conducting field studies on Utah’s Central Basin wetlands using the Utah Rapid Assessment Protocol (URAP). URAP initially focused only on evaluating wetland condition, but the UGS later added components to evaluate wetland function as well. The protocol relies on qualitative measures of condition and function, requiring surveyors to make many subjective evaluations to score sites. The UGS has conducted wetland assessment surveys across almost the entire Central Basin region in Utah (Menuz and others, 2014; Menuz and others, 2016; Menuz and Sempler, 2018; Menuz and McCoy-Sulentic, 2019; McCoy-Sulentic and others, 2021). Plant composition data are another valuable tool for evaluating wetlands and have also been collected as a part of URAP. Plant species respond to both recent and ongoing disturbances, even those that are not visible during field surveys (e.g., water quality disturbances, late season grazing), and plant communities can often be evaluated at a single point in time, rather than requiring repeat visits. The UGS has already used plant community composition data from URAP surveys to validate wetland condition scores and to separate lowand high-quality wetlands by calculating plant metrics from traits such as nativity, growth form, duration, and coefficient of conservatism value (e.g., McCoy-Sulentic and others, 2021). Those traits, however, are just the start of how plant species information can help us understand more about Utah’s wetlands. Assigning additional trait values to species found in the Central Basin would help the UGS validate other components of URAP, such as wetland function and stressor data. The goal of this project was to assign values to Central Basin plants for traits such as sensitivity to disturbances (e.g., drought, cattle grazing, nutrient increase) and for functions such as bank stability or wildlife habitat use. We then used data from one of the traits, tolerance to nutrients, to evaluate how well those data performed against other measures of site water quality. METHODS Focal Traits We developed a list of 35 traits to populate for each species. Information on traits such as root depth, root type, and stem diameter are helpful for assessing a plant’s value for erosion control potential if pre-determined erosion control potential informaUtah Geological Survey 2 tion is not directly available. Other values, such as cover and food values for different groups of fauna, can give information about a species’ value for wildlife. Tolerance to excess nutrients and tolerance to grazing were also included for measures of resiliency to human induced stressors. A full list of focal traits and their description, category, sources, and data type can be found in table 1.