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We analyzed the productivity of C₃ and C₄ grasses throughout the Great Plains of the United States in relation to three environmental factors: mean annual temperature, mean annual precipitation, and soil texture. Productivity data were collected from Natural Resource Conservation Service (NRCS) rangeland survey data. Climate data were interpolated from weather stations throughout the region. Soil texture data were obtained from NRCS State Soil Geographic (STATSGO) databases. A geographic information system was used to integrate the three data sources. With a data set of spatially random points, we performed stepwise multiple regression analyses to derive models of the relative and absolute production of C₃ and C₄ grasses in terms of mean annual temperature (MAT), mean annual precipitation (MAP), percentage sand (SAND), and percentage clay (CLAY).

MAT, MAP, and soil texture explained 67–81 …