Seasonal climate effects in sagebrush-steppe plant community production

Authors: Schantz, Merilynn; Hardegree, Stuart; Bates, Jonathan - Jon; JAMES, JEREMY - University Of California; Davies, Kirk; Sheley, Roger

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Current year management of rangeland production systems would benefit greatly from reliable seasonal forecasts of forage production which could be used for stocking rate decisions. Production forecasts are composed of two components: skillful models that relate forage production to climate; and skillful models that predict seasonal weather parameters in the upcoming management year. In this study we assessed 45 field sites in southeastern Oregon and improved site classification to predict forage production in 5 common plant communities in the Great Basin sagebrush steppe. Limiting our analysis to monthly temperature and precipitation metrics that can be forecast from currently available seasonal climate forecast models, we then determined which elements of seasonal climate contribute significantly to production modeling in each of these plant communities. This study completes the first step in developing seasonal forecasting applications for forage management in the Intermountain sagebrush steppe. Skillful seasonal forecasting could be used by numerous producer and agency managers to optimize current-year management planning in diverse rangeland settings across the western United States.

Technical Abstract: Plant production and forage availability throughout the Great Basin is largely driven by the spatial and temporal availability of precipitation and temperature. Forecasting the seasonal forage availability in these systems would greatly enhance management planning on ecosystems in the intermountain western US. Seasonal climate forecasting tools are available through the National Weather Service Climate Prediction Center (CPC), and the North American Multi-Model Ensemble (NMME) Program but prediction of forage availability also requires robust models relating seasonal climate and plant production. Late seral-stage sagebrush-steppe ecosystems across the Great Basin are diverse and support multiple native plant dominated ecological sites that are differentially affected by seasonal climate inputs depending on their soil, site, and dominant plant-species characteristics. Current production and phenology models for this ecoregion have shown significant responsiveness of forage production to seasonal precipitation and potential or reference evapotranspiration. Utilization of CPC and NMME seasonal forecast models for grazing-land applications, however, requires that forage production respond to specific inputs of monthly and seasonal precipitation and temperature. Here, we investigated the characteristics that differentiate 45 late-seral sagebrush-steppe sites in southeastern Oregon and identify how seasonal precipitation and temperature affected individual species and plant functional groups over a 10-year time period. In general, cooler and wetter spring conditions and cooler summer temperatures in the preceding year were the strongest drivers of total plant production across most ecological sites and plant functional groups. These differences, however, were both site and functional group specific. Significant responsiveness to the specific climate forecast metrics provided by the CPC and NMME program indicate that plant production forecasting is feasible for this ecosystem at multiple times during the management season.