Developing adaptation strategies using an agroecosystem indicator: Variability in crop failure temperatures

Crop failure temperatures (CFTs) are critical temperature thresholds for plants beyond which plant tissue has a high potential of being damaged. Climatic changes resulting in fewer or more CFTs have important implications for agriculture. Examining CFT trends can provide information that will assist plant breeders and agricultural producers to develop new adaptation strategies for crop and livestock selection, and thereby safeguard the general food supply. Six CFTs temperatures [maximum temperatures (Tmax) ≥ 30 °C, 32 °C, 34 °C, 35 °C, 39 °C and 40 °C] were considered in this study. The variability frequency and intensity of CFTs were analyzed over both short-term (four time-periods; initiation of recordkeeping up to 1920, 1921-1950, 1951-1980, and 1981-2009) and long-term (100-year) time-periods, using data from 23 weather stations spread across Kansas, USA. Results indicated that ∼75% of long-term trend values across all CFTs and locations decreased, one remained the same (less than 1%), and ∼25% had positive trend values. About 91% of long-term trend values fell between 1 and −1 day/decade. Overall, the range in the number CFT days was greatest at 30 °C and steadily decreased as CFT increased, with a 10-fold decrease in the range of the number of CFT days at 40 °C CFT. However, 53% of all 30-year trend lines with absolute slope values of >6 days/decade occurred during the 1981-2009 time-period. The greatest changes in slope were also recorded during this time-period, with 9 slopes greater than 10 days/decade. Thus, the greatest changes in number of CFT days, along with the greatest number of sites experiencing decreases in CFT days occurred during the most recent time-period. Eastern Kansas had the most and largest decreases in CFT days across all CFTs.