Management Implications of Global Change for Great Plains Rangelands

The Great Plains of North America encompass approximately 85 million ha (210 million acres) consisting of shortgrass, mixed-grass, and tallgrass prairie with about 60% of this area converted to crop agriculture and the remainder used primarily for livestock production. Large-scale gradients of precipitation (west to east, <30 to >100 cm; <12 to >40 inches) and mean annual temperature (north to south, 2 to 18°C; 36 to 64°F) determine vegetation patterns. For example, the precipitation gradient infl uences biomass production (1,000 to 6,200 kg · ha−1; 900 to 5,500 pounds · acre−1), canopy height (<20 to >200 cm; <8 to >80 inches), and overall resource limitations governing plant–soil interactions. Both soil carbon and nitrogen (N) increase from west to east, whereas root:shoot ratios decrease (18–25:1 to 3–5:1). The temperature gradient infl uences the distribution of cool(C3) and warm-season (C4) species, with C3 species more prevalent in northern latitudes, and C4 species more abundant in the southern half of the Great Plains. We expect that global change will impact Great Plains rangelands largely through changes in the master environmental variables of moisture and temperature. However, the combined impacts of global change will vary across the region. Herein we summarize the latest fi ndings and implications in global change research pertinent to rangelands of the Great Plains. A summary of the following major points can be found in the sidebar.