PS 53-206 - Evolution of prolonged dormancy is influenced by past weather events

Background/Question/Methods

Prolonged dormancy refers to perennial plants staying below ground for one or more growing season. This life history strategy is exhibited by many perennial herbaceous plants. Recent study shows that the evolution of prolonged dormancy may be influenced

by resource allocation including remobilizing stored non-structural carbohydrates. This might be particularly important in resource limited environment, where plant need to store resources over several years to perform important functions. Resource accumulation is influenced by weather variables such as rainfall and temperature, and it is possible that the response of prolonged dormancy to weather may be delayed. We hypothesize that, weather variables intensifying the water deficit of plants influence the transitions in and out of prolonged dormancy because resource accumulation is influenced by water availability. We tested this hypothesis using a 32year long datasets of the perennial herbaceous plant, Astragalus scaphoides.
We used GLMMs with year as a random effect to estimate the probabilities of: large and flowering plants emerging from prolonged dormancy, and small, large and flowering plants entering prolonged dormancy. We then applied functional linear models of lagged weather data to identify the monthly contribution of each weather variable to prolonged dormancy.

Results/Conclusions

We found that, flowering individuals emerge from prolonged dormancy when they experience higher than normal winter/spring temperature in the past year (between 15-20 months in the past) and cool winter/spring temperature during the current year (from the 3rd month prior to July to the 1st month in the current year). Large individuals sprouts from prolonged dormancy when drier than average conditions (19-26 months in the past) is followed by wetter than average conditions the current year (0-6 month in the past). Small, Large, and Flowering individuals are more likely to enter dormancy if these stages experience higher than normal temperature for about 22 months before the July of the current year.

In conclusion, the evolution of prolonged dormancy is likely influenced by resource dynamics over several growing seasons. Weather variables influence resource acquisition of plants leading to the observed delayed effect of weather conditions on prolonged dormancy.