Ecosystems respond to environmental changes through a suite of processes ranging in timescale from minutes to centuries. While the quickest ones (physiological changes, phenological shifts) may track climate change, slower ones (community composition turnover, evolutionary adaptation) will likely lag behind. I study the consequences of those lags on ecosystem functions (plant productivity, habitat provision) that are crucial for wildlife and as economically important natural resources. Currently, I am leading an interdisciplinary group of researchers to synthesize knowledge and develop mathematical theory to understand ecological acclimation.

Pollination is one of the most important plant-animal mutualism, and the timing of this interaction is being shifted by warming temperatures. By tracking bee and flower phenology in the Colorado Rocky Mountains I work to understand what pollination will look like in the future, and whether plants and insect populations will be impacted by warming. Some key findings from my work so far have been that bee shift their foraging in response to snowmelt timing, but that the end of their flight seasons are determined by functional traits. I've also found that both bee and flower phenological distributions tend to be skewed toward the late season, and I've developed new quantitative tools to pull information from asymmetrical phenology data. Currently, I'm examining whether the timing of pollination interactions themselves is sensitive to climatic variation in the same ways as bee and flower abundances.

In order to understand how various ecosystems are responding to climate change, we need harness globally-distributed data. Fortunately, numerous countries have been tracking phenological events for decades, and there is rapidly growing citizen-scientist data that can offer big-picture insights. Using data from 23 countries across the Northern Hemisphere, I study how warming is affecting bird migration, insect emergence, plant leaf-out, and flowering time. Contrary to expectations, I've found that while spring phenology is generally advancing rapidly as the climate warms, it is not becoming more variable, either over time or in warmer years.