​species range limits & climate change

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​The questions of which biotic and abiotic mechanisms determine species geographic distributions, and how these will shift with climate change, lie at the heart of my research interests. In order to identify which abiotic and biotic parameters are most influential for population persistence, I conduct extensive population surveys and use quantitative ecological modeling methods. Coupled with existing climate projections, this research will contribute to the knowledge base necessary to predict species range shifts with increased accuracy.
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My previous work on the endemic Pinus coulteri (Pinaceae) in California montane ecosystems showed that species' latitudinal and climatic limits do not necessarily occur together, a common assumption in this field of research. I am currently studying the alpine cushion plant Silene acaulis (Caryophyllaceae) in both the Colorado Rocky Mountains and Swiss Alps, in order to understand what factors determine its local and global distribution.


​species interactions & disturbances​


For decades, we have understood that both local and global disturbances can have major influences in species distributional patterns and community composition. However, it is unclear how disturbances affect species interactions within communities. Such interactions are essential for maintaining biodiversity in alpine systems, systems which are particularly susceptible to the effects of climate change and are experiencing increased disturbances from hiker trampling. 

​My dissertation work in alpine systems seeks to answer how human trampling disturbance affects Silene acaulis populations and the facilitative and competitive interactions within. In the Colorado Rocky Mountains (interview and video summary), trampling disturbance favors S. acaulis at lower, not upper, elevational range limits by increasing competitor-free space. In the Swiss Alps (interview), disturbance has negative effects on S. acaulis reproduction and population density, as well as on species community richness. 


​​global distribution patterns


I focus this work on alpine ecosystems world-wide, which allows me to make broad ecological generalizations. Using existing population performance data and global occurrence records, I seek to answer if local population adaptation to climate is important in determining Silene acaulis' distribution. Global data on beneficiary species growing within S. acaulis cushions furthermore allows me to examine how the reciprocal effects of these species on their host vary across S. acaulis' climate envelope. A more concrete understanding of the effects of local adaptation to climate, a widely used predictor for species' range shifts, and the potentially variable biotic effects in different climate regions will allow for increased accuracy in projecting species' range shifts.
Funding for this work is generously provided by: Zeno Karl Schindler Foundation; American Alpine Club; Environmental Studies Program at University of Colorado, Boulder; Indian Peaks Wilderness Alliance; John Marr Ecology Fund; Hazel Schmoll Research Fellowship; Botanical Society of Switzerland.