Primary Production of the Central Grassland Region of the United States

TLDR

Grassland net primary production is strongly driven by the amount and distribution of annual precipitation. Across 9,500 sites in the central United States, aboveground net primary production was found to be governed primarily by annual precipitation, with an east‑west gradient of higher yields in the east that shifts with precipitation extremes, and site‑level productivity explained by precipitation, soil water‑holding capacity, and their interaction, supporting the inverse texture hypothesis that sandy soils outperform loamy soils when precipitation is below 370 mm yr⁻¹ and vice versa.

Abstract

Aboveground net primary production of grasslands is strongly influenced by the amount and distribution of annual precipitation. Analysis of data collected at 9500 sites throughout the central United States confirmed the overwhelming importance of water availability as a control of production. The regional spatial pattern of production reflected the east—west gradient in annual precipitation. Lowest values of aboveground net primary production were observed in the west and highest values in the east. This spatial pattern was shifted eastward during unfavorable years and westward during favorable years. Variability in production among years was maximum in northern New Mexico and southwestern Kansas and decreased towards the north and south. The regional pattern of production was largely accounted for by annual precipitation. Production at the site level was explained by annual precipitation, soil water—holding capacity, and an interaction term. Our results support the inverse texture hypothesis. When precipitation is <370 mm/yr, sandy soils with low water—holding capacity are more productive than loamy soils with high water—holding capacity, while the opposite pattern occurs when precipitation is >370 mm/yr.