Vulnerability of rangeland beef cattle production to climate‐induced NPP fluctuations in the US Great Plains

• Published in: Global change biology 2020-09, Vol.26 (9), p.4841-4853
• Main Authors: Klemm, Toni, Briske, David D., Reeves, Matthew C.
• Format: Article
• Language: English
• Subjects: adaptive capacity; Animals; Beef; Beef cattle; Cattle; Cattle production; Climate; Climate Change; Climate variability; Computer simulation; ecological sustainability; economic sustainability; Economics; Ecosystem; exposure; Extreme values; Forecasting; Impact analysis; Net Primary Productivity; Primary production; Rangelands; Regions; sensitivity; Sustainability; Variability; Vulnerability
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.15202

The vulnerability of rangeland beef cattle production to increasing climate variability in the US Great Plains has received minimal attention in spite of potentially adverse socioeconomic and ecological consequences. Vulnerability was assessed as the frequency and magnitude of years in which net primary production (NPP) deviated >±25% from mean values, to represent major forage surplus and deficit years, for a historic reference period (1981–2010), mid‐century (2041–2065), and late‐century (2075–2099) periods. NPP was simulated by MC2, a dynamic global vegetation model, driven by five climate projections for representative concentration pathway (RCP) 4.5 and 8.5. Historically, 4–4.7 years per decade showed either NPP surpluses or deficits. The future number of extreme years increased to 5.4–6.4 and 5.9–6.9 per decade for RCP 4.5 and 8.5, respectively, which represents an increase of 33%–56% and 38%–73%, respectively. Future simulations exhibited increases in surplus years to between 3 and 5 years in the Northern Plains and 3–3.5 in the Southern Plains. The number of deficit years remained near historic values of 2 in the Northern Plains, but increased in the Southern Plains from 2.5 to 3.3 per decade. Historically, NPP in extreme surplus and deficit years both deviated 40% from mean NPP in all three regions. The magnitude of deficit years increased by 6%–17% in future simulations for all three regions, while the magnitude of surplus years decreased 16% in the Northern Plains and increased 16% in the Southern Plains. The Southern Plains was the only region to exhibit an increase in the magnitude of both surplus and deficit years. Unprecedented future variability of NPP may surpass the existing adaptive capacity of beef producers and adversely impact the economic viability of rangeland cattle production and ecological sustainability of rangeland resources. The vulnerability of rangeland beef cattle production in the US Great Plains was assessed by simulating annual NPP throughout the century with a dynamic global vegetation model. Minor changes in mean decadal NPP belie large increases in inter‐annual variability. Historically, 4–4.7 years per decade had annual NPP that varied at least ±25% from the long‐term mean, but these forage surplus and deficit years increased to 5.4–6.9 years per decade in future simulations. Greater inter‐annual variability may surpass the existing adaptive capacity of beef producers to adversely impact the economic viability, and c