Estimating Production of Range Vegetation from Easily Measured Soil Characteristics

Abstract

AbstractVegetation production information is essential to rangeland management. Making range production estimates based on harvest data is expensive and time consuming. Few native range sites in Montana or comparable areas have long‐term production data. We therefore classified soil pedons on such sites, and tested thickness of mollic epipedon and other site characteristics as predictors of average range production. Specifically Mollisols under native range with 6‐ to 49‐ yr production records were examined at 14 sites in Montana, Wyoming, North Dakota, and Alberta, Canada. Sites ranged in precipitation, elevation, and latitude from 250 to 560 mm/yr, 595 to 2165 m, and 40 to 50° north. Mean annual standing crop production ranged from 0.4 Mg/ha on a coarse‐loamy, mixed, Aridic Haploboroll to 3 Mg/ha on a fine, montmorillonitic, Agric Cryoboroll. Thickness of mollic epipedon and Munsell color values were recorded for 30 samples per site. Multiple linear regression analysis showed thickness of mollic epipedon predicts long‐term production better than any other single factor tested, R2 = 0.39. Addition of precipitation data improved estimates of production and gave the equation: production (Mg/ha) = −1.34 + 0.023 [thickness of mollic epipedon (cm)] + 0.005 [precipitation (mm)], R2 = 0.72. Separation of sites by vegetation improved correlations between thickness of mollic epipedon and production, possibly because it grouped sites climatically. For Stipa/Bouteloua vegetated sites, production (Mg/ha) = 0.32 + 0.023 [thickness of mollic epipedon (cm)], R2 = 0.66. Depth to carbonates was also related to production.