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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #397053

Research Project: Development of Management Strategies for Livestock Grazing, Disturbance and Climate Variation for the Northern Plains

Location: Livestock and Range Research Laboratory

Title: Modeling herbaceous biomass for grazing and fine fuels management in central Arizona

item RHODES, EDWARD - Texas A&M Agrilife
item TOLLESON, DOUGLAS - Texas A&M Agrilife
item Angerer, Jay

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2022
Publication Date: 10/12/2022
Citation: Rhodes, E.C., Tolleson, D.R., Angerer, J.P. 2022. Modeling herbaceous biomass for grazing and fine fuels management in central Arizona. Land. 11(10). Article 1769.

Interpretive Summary: The ability to predict the amount of herbaceous plant biomass would assist land managers in fire and livestock management decisions. Herbaceous plant production serves as the primary fuel for fire spread but is also the primary food source for most livestock grazers. In this study, a computer simulation model called the Phytomass Growth Simulator (Phygrow) was used to predict herbaceous plant biomass on desert, juniper, and pine landscapes found within the Coconino National Forest in Arizona. The simulations were built using plant community, soil, and grazing data collected from field sites. Model outputs were compared to herbaceous plant biomass measured quarterly over a 2-year period. The Phygrow model predicted herbaceous plant biomass well across years for the desert and pine areas, but the prediction ability was less on juniper dominated sites. The Phygrow model performed well for predicting herbaceous plant biomass for all areas during the fire season (summer months) indicating that the model would be useful for fire management decisions.

Technical Abstract: Both grazing and fine fuels management are dependent on the temporal and spatial distribution of herbaceous biomass production. Rangeland and wildland fire managers can both benefit from knowing when and where there is excessive herbaceous biomass buildup. In this study, we compared modeled herbaceous biomass outputs from the Phytomass Growth Simulator (Phygrow) to observe and predict herbaceous production on desert, juniper, and pine sites on the Coconino National Forest in Arizona. Models were validated with: a) 2 years of quarterly data, and b) fire season-only data. The Phygrow model showed strong correlation between observed and predicted values year-round on the desert and pine sites, and a lower, but positive correlation in the juniper sites. Fire season predictions were strong for all ecosystem types, suggesting that the Phygrow model is well suited to provide valuable decision support information with which to address rangeland and fire management objectives.