Abstract
听听Alpine areas are experiencing faster rates of warming due to climate change than lowland regions, and this warming leads to earlier snowmelt. Early snowmelt and warming temperatures pose threats to alpine ecosystems, and plants are particularly susceptible because of their slow dispersal rates. While earlier snowmelt can benefit plants by increasing the number of growing degree days, it can also expose plants to damaging frost events, and atypically high temperatures can decrease reproductive success. Understanding what these changes will mean for plant communities is critical for protecting diversity in alpine ecosystems. While some studies have looked at the effects of either warming or early snowmelt on alpine plants, few have examined the combination of the two changes, or investigated the role of landscape in buffering plant population from climate change. In complex heterogeneous alpine landscapes microtopography and local mesoclimate conditions can provide refugia where the negative effects of climate change may be less severe. Using a manipulative factorial experimental design in the Colorado Rocky Mountains, I examined how early snowmelt, warming, and the combination of the two impact in situ seed germination rates of the widespread forb Geum rossii. I also examined the role of landscape position and small-scale microtopography variables in predicting germination rates. Additionally, I analyzed the effect of field treatments on seed quality and germinability. I found that landscape position was the most significant predictor of germination, with higher germination rates corresponding to wetter conditions. Early snowmelt significantly decreased germination rates but only in wet meadow locations. Germination rates also decreased as terrain steepness increased. These results show that conservation efforts for Geum rossii should focus on wet meadow locations with relatively level terrain. Informed management practices can protect Geum rossii populations, helping to preserve biodiversity in sensitive alpine ecosystems.
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-Nyika