Jake Weltzin visited K-State last week. Jake has been the Executive Director for the National Phenology Network for 5 years. The USA NPN is a joint effort between USGS and University of Arizona with a range of partners from the National Park Service to the Appalachian Mountain Club.
The logistics of a national survey of phenology are interesting, but the science is more interesting. The timing of ecological events is critical for function. Ecosystems are never in perfect balance, but the success of populations and key processes is highly dependent on the synchrony (or asynchrony) of events.
The longest running phenology study in the US extends back over 50 years when cloned lilacs were first distributed and their phenology monitored. [We have one in our front yard]. Weltzin showed lilacs have been blooming earlier in the spring in the northern and western parts of the US, but not the Southwest, which has been hypothesized to be associated with regional patterns of warming that hadn't previously been explored.
Currently USA-NPN provides the opportunity to monitor over 800 species of plants and animals. They have a slick web and smartphone interface for inputting data. More importantly, it's a good excuse to get outside and watch nature.
http://www.usanpn.org/