Climatic Change

, Volume 114, Issue 3, pp 723–744

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

Article

DOI: 10.1007/s10584-012-0448-y

Cite this article as:
Mix, K., Lopes, V.L. & Rast, W. Climatic Change (2012) 114: 723. doi:10.1007/s10584-012-0448-y

Abstract

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 GDD10, GDD4.4 (potato) and GDD5.5 (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.

Supplementary material

10584_2012_448_MOESM1_ESM.docx (18 kb)
Table S-1Results of t-test analyses for the ordinal day of the last vernal and first autumnal freezes and length of the freeze-free period in the San Luis Valley, Colorado. Negative values in the difference column for the vernal dates indicates an earlier last freeze. (DOCX 18 kb)
10584_2012_448_MOESM2_ESM.docx (20 kb)
Table S-2Results of t-test analyses for maximum temperature of each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in the average maximum temperature. (DOCX 19 kb)
10584_2012_448_MOESM3_ESM.docx (20 kb)
Table S-3Results of t-test analyses for minimum temperature of each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in the average minimum temperature. (DOCX 19 kb)
10584_2012_448_MOESM4_ESM.docx (20 kb)
Table S-4Results of t-test analyses for mean temperature of each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in the average mean temperature. (DOCX 19 kb)
10584_2012_448_MOESM5_ESM.docx (20 kb)
Table S-5Results of t-test analyses for GDD10 for each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in mean GDD. (DOCX 19 kb)
10584_2012_448_MOESM6_ESM.docx (20 kb)
Table S-6Results of t-test analyses for GDD4.4 for each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in mean GDD. (DOCX 19 kb)
10584_2012_448_MOESM7_ESM.docx (20 kb)
Table S-7Results of t-test analyses for GDD5.5 for each month of the growing season in the San Luis Valley, Colorado. Difference represents the daily increase or decrease in mean GDD. (DOCX 19 kb)

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Department of AgricultureTexas State UniversitySan MarcosUSA
  2. 2.Department of BiologyTexas State UniversitySan MarcosUSA

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