Climate change is shifting environmental cues that influence species lifecycle patterns, and such changes can affect interspecific interactions. Phenological mismatches between plants and pollinators can result because both taxonomic groups are especially vulnerable to changes in environmental cues. Changes in phenology can weaken or eliminate interactions between community members and the abiotic environment. This research seeks to understand how predicted climatic scenarios of increased temperature and decreased spring snowpack may affect a spring flowering plant, arrowleaf balsamroot (Balsamorhiza sagitatta), found in montane meadows. Twelve plots, three of each with an assigned treatment of heating (H), snow removal (SR), heating + snow removal (HSR), or control (C), were monitored for flower onset, flowering duration, number of concurrent flowers, and number of buds damaged by frost for each individual balsamroot plant from 2013-2019. Snow was removed in the spring prior to the flowering season and heating was accomplished using passive warming structures placed over the experimental plots. We expected snow removal and heating to have compounding effects, resulting in earlier flower onset, extended flower duration, and a greater number of concurrent flowers, while an increased number of buds damaged by frost would occur in the snow removal treatment.
Results/Conclusions
All treatments showed a significant advance in flower onset, extended flower duration, and a greater number of concurrent flowers in comparison to controls. The most substantial advance in flowering onset of 4.2 days occurred in the SR treatment, but HSR and H also showed advancements in flowering onset. Flowering duration showed the largest response to the HSR treatment (4.9 days longer), with the SR treatment and H treatment also showing longer times compared to the control. The number of concurrent flowers was most affected by HSR treatment (4.7 more flowers), with less dramatic but increases associated with SR and H treatments. There was a marginal effect of treatment on the number of buds damaged by spring frost with the SR treatment having 0.21 more buds damaged by frost compared to the control. Heating treatments mitigated frost damage with H having 0.30 fewer and HSR having 0.04 fewer buds damaged by frost compared to the control. These results show that soil temperature and spring snowpack are significant drivers of arrowleaf balsamroot phenology. An extension of the flowering period, observed in these results, could potentially compensate for an advance in flowering date, minimizing potential trophic mismatches between arrowleaf balsamroot and its pollinators.