Experimentally simulating climate change in a montane meadow system via reduced snowpack and passive warming: soil and plant responses

Background/Question/Methods

In order to mitigate the effects of climate change, we need to better understand how ecological systems are being affected by changing conditions. To explore the consequences of increased temperatures and decreased snow cover, we conducted an experiment in a montane meadow ecosystem.  Snow removal and passive heating were used to mimic the effects of predicted environmental changes. We manipulated soil temperature using open-sided passive warming chambers, and soil moisture by manually removing snow in the spring of 2010 and 2011. Our treatments included control, snow removal (SR), passive warming (H+), and snow removal + passive warming (HSR). We measured soil temperature at the surface and soil moisture at a 25cm depth in order to confirm that open-sided passive warming chambers and manual snow removal would have the predicted effects on temperature and moisture. In 2011, we recorded plant phenological response dates for emergence (green-up), budding, flowering, and senescence in three common perennial plants (Arrowleaf Balsamroot (Balsamorhiza sagitatta), Wild Buckwheat (Eriogonum umbellatum), and Western Groundsel (Senecio integerrimus)) in each of the treatments. Frost damage was recorded in Arrowleaf Balsamroot (Balsamorhiza sagitatta) in 2011.

Results/Conclusions

Preliminary data show soil minimum nighttime temperature at 25 cm was significantly increased in the H+ treatments, while soil maximum daily temperatures were not, resulting in a significant increase in the range between maximum and minimum soil temperatures. Soil moisture at 25 cm was decreased throughout the season in the SR treatment when compared to the control in 2011 but not 2010. Soil moisture was not significantly different in 2010 or 2011 among other treatments. Plant emergence was significantly earlier in B. sagitatta in the SR and H+ treatments but not in the HSR treatments, while budding time was advanced in the SR and HSR treatments but not H+ treatments. Green-up time was advanced in E. umbellatum in the SR and HSR treatments. The treatments had no impact on phenology of S. integerrimus. These preliminary results indicate that 1) the open-sided passive warming chambers significantly increased 25 cm depth soil minimum nighttime temperatures but had no impact on soil maximum temperatures, 2) removal of late season snow can lower soil moisture throughout the growing season, but initial snow depth affects this result, and 3) removal of late season snow advanced phenological stages of some, but not all forb species examined.