Modeling crop overwintering Focus on survival

Transcription

1 Modeling crop overwintering Focus on survival Giulia Vico, VPE April 2th, 21 Modelling of crop survival Air temperature, snow cover Crown temperature detailed models of snow dynamics vs. semi-empirical models 1

2 Modelling of crop survival Air temperature, snow cover Crown temperature detailed models of snow dynamics vs. semi-empirical models Acclimation and deacclimation Crop tolerable temperature generally expressed as temperature lethal for % of the individuals, LT (e.g., Fowler 1999, Le Comte 23, Bergjord et al. 28) Low temperature damage Within-crop variability in response Probability of survival Temperature of exposure ( C) Regrowth tests show that crop response to low temperature is not threshold like Reconstruct the fraction of surviving plants, by including the shape of the survival curve Obtain practical information e.g. under which conditions 1% of the plants are lethally damaged 2

3 Miniumum survival probability over the whole winter Today s probability of survival Probability of survival Today s survival curve, as the result of acclimation and deacclimation Minimum survival probability over the season: Probabilistic measure of low temperature damage Temperature of exposure ( C) Today s crown temperature, as the result of air temperature and snow Application to winter wheat in Sweden Min survival prob. Northern locations (9-62 N) Colder (average winter temp <-1 C) Continuous, deeper snow cover Southern locations (-7 N) Warmer (average winter temp>2 C) Shallower and less continuous snow cover 3

4 INCREASING TEMPERATURE Minimum survival probability Min survival prob. Northern/colder locations: High survival probability Intermediate locations: lowest (and most variable) survival probability Southern/warmer locations: High survival probability Latitude and average temperature do not explain the whole pattern INCREASING TEMPERATURE Minimum survival probability Minimum survival prob. Real conditions Minimum survival prob. Neglecting snow The high survival probability in northern locations can be explained with continuous snow cover 4

5 Snow manipulation experiment AMBIENT REDUCED SNOW - Ultuna, Winters , Two winter wheat varieties: Olivin and Björka - Snow treatments: ambient, reduced - Three harvests: late fall, early spring, late spring - Continuous measurements: soil temperature, snow depth Snow manipulation experiment EFFECT ON GROWING CONDITIONS Snow manipulation created different growing conditions (when snow was present) Snow depth (cm) h sn (cm) Crown T ( o C) Temperature ( C) Jan th Jan 2th Feb th Jan th Jan 2th Feb th Reduced snow Control Enhanced snow

6 Snow manipulation experiment EFFECT ON GROWING CONDITIONS Snow manipulation created different growing conditions (when snow was present) EFFECT ON WINTER WHEAT In , no significant effect of snow treatment or variety on - survival rate - plant biomass and early vigor Snow depth (cm) h sn (cm) Temperature T ( o C) ( C) Jan th Jan 2th Feb th Jan th Jan 2th Feb th Reduced snow Control Enhanced snow Conclusions and implications Snow plays a crucial role on - crop sensed temperature - acclimation and deacclimation - survival Effect of climate change may be positive or negative depending on the interplay between air temperature and snow giulia.vico@slu.se 6

7 Conclusions and implications Snow plays a crucial role on - crop sensed temperature - acclimation and deacclimation - survival The shape of the probability of survival curve impacts the extent of lethal damage in a complex way Effect of climate change may be positive or negative depending on the interplay between air temperature and snow This aspect must be considered to - determine the survival rate - assess if a change in variety can offset the effects of climate change Combine survival with plant resource storage and spring vigor giulia.vico@slu.se Mean winter average daily temp. ( C) EFFECT OF CLIMATE CHANGE Space x time substitution - Minimum survival prob. The same increase in temperature enhances risk of winter damage in currently colder locations reduces risk of winter damage in warmer location (where snow is already insufficient) 7