Warming winters, changing springs: cold hardiness dynamics predict budbreak and associated low temperature threats on an intercontinental scale
Warming winters, changing springs: cold hardiness dynamics predict budbreak and associated low temperature threats on an intercontinental scale
Campos-Arguedas, F.; Kirchhof, E.; North, M. G.; Londo, J. P.; Bates, T.; van Leeuwen, C.; Destrac-Irvine, A.; Bois, B.; Kovaleski, A. P.
AbstractTemperate woody perennial plants form buds during late summer that contain leaves and flowers that emerge in the following growth season. To survive winter, dormant buds must attain cold hardiness, and timely lose it in spring to break bud while avoiding damage from low temperatures and late frosts. Here, we use an untrained process-based model to predict bud cold hardiness of three grapevine varieties (V. vinifera \'Cabernet-Sauvignon\' and \'Riesling\', and V. hybrid \'Concord\') from historical temperature records of eight different locations in North America and Europe (n = 329). Based on those predictions, and thresholds of cold hardiness at budbreak from literature, timing of budbreak was extracted. Despite being untrained to the data, the RMSE of budbreak predictions was 7.3 days (Bias=-0.83). Based on cold hardiness estimations and air temperature records, low temperature damage was quantified and validated through newspapers and extension records. In years x location where damage was predicted, corrections to budbreak based on delays expected resulted in improvements of predictions (RMSE=7.2d, Bias=0.58). Predictions of instances of freeze damage risk demonstrate genotypic adaptation to different environments. At the species level, increasing or decreasing trends in freeze damage risk are predicted, depending on the range of mean dormant season temperature (MDST; 1 Nov - 30 Apr) present in each location. Sensitivity analysis of predicted time to budbreak based on MDST shows a general advancement of phenology at -5.8d/{degrees}C. However, in much warmer locations, delays can be expected as temperatures continue to increase (+1.9d/{degrees}C for MDST>10{degrees}C). Through cold hardiness dynamics, the estimation of chilling accumulation appears as an important source of error for predictions of spring phenology across environments. Cold dynamics represents an advancement in phenological modeling that provides information for the entirety of the dormant season, as well as budbreak.