Phenological Monitoring: A key approach to assessing the impact of spring 
starting earlier
Mark D. Schwartz*, Geography Department, University of Wisconsin-Milwaukee, WI  

Phenology, the study of periodic plant and animal life cycle events that are influenced by 
environmental changes, is a key approach to assessing the impact of spring starting earlier 
on individual species and whole ecosystems. These data have not been collected for 
multiple species over large geographic areas in the past, but general assessments are still 
possible using phenological models driven by weather data. Such studies have shown that 
the start of spring has been getting earlier at an average rate of one or more days per 
decade since 1955 across the Northern Hemisphere. A USA National Phenology Network is 
being developed to provide a richer source of phenological information across the country 
that can facilitate understanding of the impacts of climate change on plants and animals, as 
well as inform future management and adaptation decisions.
*Presenter