Climate change and urbanization are changing the seasonal growth cycles, or phenology, of trees, leading to significant impacts on local and regional ecosystems such as alterations in bird migration and agricultural practices.  However, the ability to effectively monitor these changes in tree phenology is limited by challenges in capturing high-quality data over large geographic and time scales. This is especially true in urban environments where access to trees is difficult due to a lack of inexpensive, non-invasive monitoring methods, leading to gaps in our understanding of climate change impacts on various tree species and their seasonal growth patterns.

In a recent article in Agricultural and Forest Meteorology, researchers from the USGS, including North Central CASC Research Ecologist Brian Miller and Research Hydrologist Jonathan Friedman, and partners used accelerometer sensors to overcome some of the barriers in monitoring tree phenology. As trees go through seasonal cycles of growing and losing foliage and flowering, their mass changes, which then changes how they sway in the wind. Accelerometers can be placed on trees to record these changes in sway. By collecting and analyzing this tree sway data over a full growing season, the research team was able to successfully detect life cycle transitions for individual trees in an urban environment with a level of detail and efficiency that is not available in other monitoring methods. 

This novel use of accelerometers has the potential to provide real-time, high-resolution data on seasonal tree growth in both urban and forested environments in a way that is both low-cost and non-invasive. The authors highlight that implementing accelerometers across broader regions could revolutionize large-scale studies of how climate and land use changes are affecting seasonal tree growth and health.