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Growing season expansion and related changes in monthly temperature and growing degree days in the Inter-Montane Desert of the San Luis Valley, Colorado


  • Ken Mix


  • Vicente Lopes
  • Walter Rast


Most climate change studies on high elevation ecosystems identify changes in biota, while several report abiotic factors. However, very few report expansion of the freeze-free period, or discuss monthly changes of temperature and growing degree days (GDD) during the growing season. This study provides initial data on agriculturally-related aspects of climate change during the growing season (M-J-J-A-S) in the inter-montane desert of the San Luis Valley (SLV), Colorado. Temperature data were gathered from 7 climate stations within the SLV. Based on ordinal days, the last vernal freeze is occurring (p > 0.05) earlier at 3 stations than in prior years, ranging between 5.52 and 11.86 days during 1981–2007. Significantly-later autumnal freezes are occurring at 5 stations by 5.95–18.10 days, while expansion of the freeze-free period was significantly longer at all stations by 7.20–24.21 days. The freeze-free period averaged about 93 days prior to the 1980s, but now averages about 107 days. Increases (p > 0.05) in daily mean, maximum, minimum temperature occurred at nearly all stations for each month. Increases in GDD 10 , GDD 4.4 (potato) and GDD 5.5 (alfalfa) also occurred at nearly all stations for all months during 1994–2007. Higher temperatures increase the number of GDD, quickening crop growth and maturity, and potentially reducing yield and quality unless varieties are adapted to changes and water is available for the season extension and increased evapotranspiration. Copyright Springer Science+Business Media B.V. 2012

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  • Ken Mix & Vicente Lopes & Walter Rast, 2012. "Growing season expansion and related changes in monthly temperature and growing degree days in the Inter-Montane Desert of the San Luis Valley, Colorado," Climatic Change, Springer, vol. 114(3), pages 723-744, October.
  • Handle: RePEc:spr:climat:v:114:y:2012:i:3:p:723-744
    DOI: 10.1007/s10584-012-0448-y

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    References listed on IDEAS

    1. Robert Finger & Stéphanie Schmid, 2008. "Modeling agricultural production risk and the adaptation to climate change," Agricultural Finance Review, Emerald Group Publishing, vol. 68(1), pages 25-41, May.
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