Does the signature of sea surface temperature anomalies influence livestock production in the Western Great Plains?

Authors: Raynor, Edward; Derner, Justin; Augustine, David; CHEN, MAOSI - Colorado State University; PARTON, WILLIAM - Colorado State University; HARTMAN, MELANIE - Colorado State University; Wilmer, Hailey; Porensky, Lauren

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/24/2018
Publication Date: 2/10/2019
Citation: Raynor, E.J., Derner, J.D., Augustine, D.J., Chen, M., Parton, W., Hartman, M.D., Wilmer, H.N., Porensky, L.M. 2019. Does the signature of sea surface temperature anomalies influence livestock production in the Western Great Plains?. Society for Range Management Meeting Abstracts. P 83.

Interpretive Summary:

Technical Abstract: The impact of Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO) sea surface temperature anomalies has been demonstrated for aboveground net primary production (ANPP) in semiarid rangelands of the western Great Plains. During cold phase PDOs, mean ANPP was lower and more variable, and the frequency of low ANPP years (drought years) was much higher compared to warm PDO years. When ESNO index values were negative (El Niño), there was a higher frequency of droughts and lower frequency of wet years and higher ANPP regardless of the PDO phase. When PDO was in a warm phase and ENSO was positive (La Niña), drought only occurred about 20% of the years; when PDO was in a cool phase and ENSO was negative (El Niño), drought occurred almost half of the years. Questions remain though as to the influence of sea surface temperature anomalies on secondary (livestock) production (kg/ha) in these rangelands. Here, we use a long-term (since 1939) grazing intensity study at the USDA-Agricultural Research Service’s Central Plains Experimental Range, a Long-Term Agroecosystem Research (LTAR) site, with livestock production data from light,(20% use), moderate (40% use), and heavy (60% use) grazing treatments. We hypothesize that the influence of sea surface temperature anomalies on livestock production is more pronounced with heavy than moderate grazing, and the effects are more prominent during cold phase PDOs and when ENSO is negative (El Niño). We hypothesize that livestock production in the light grazing treatment largely unaffected by sea surface temperature anomalies due to the very conservative stocking rate employed in this treatment. We also relate these findings to rancher decision-making in this ecosystem with the recent switch in the PDO phase from cold (1998-2013) to warm (2014-present).