Arid and semi-arid systems are water limited systems that are likely to exhibit phenological shifts with changes in climate. Seeds use soil temperature and water content as cues for germination, and are likely affected by changes in climate that alter precipitation and temperature. Changes in germination timing could lead to new plant interactions, exposure to freezing conditions, and different resource availability. The SHAW (simultaneous heat and water) model can accurately estimate soil conditions from historic climate data, which can be used to calculate germination timing using wet thermal calculations. Using this model, we calculated time (in days) for 10 native plant species to germinate at 10 sites in the sagebrush steppe system during the years 1979-2016.
Results/Conclusions
Our results show extreme annual variability in germination timing, with cyclical patterns of late and early germination dominating the years 1979-2001, and a steadier pattern of accelerating germination timing during the years 2001-2016. Germination timing was delayed during the period of 1979-1988, showed little to no change 1989-2000, and accelerated 2001-2016. Germination timing of species in 2016 is not different from timing seen during historic years, but cyclic germination patterns seen in past years are less apparent during 2001-2016. Germination responses of our analyzed species responded similarly across time implying similar phenological responses to changes in climate during the period of this study.