Phenology Phenology is the study of living organisms’ response to seasonal and climatic changes in their environment. Seasonal changes include variations in day length or duration of sunlight, precipitation, and temperature.

Phenology Plant growing season generally corresponds to the period between green-up and green-down. Growing season directly related to global carbon fixation and the amount of CO 2 in the atmosphere. Timing of green-up and green-down is important for understanding the global water cycle. –As plants photosynthesize, they also transpire water from the soil into the atmosphere

Phenology Green-up and green-down data are used to examine: –regional and global vegetation patterns –year-to-year trends –vegetation responses to climate change –wild fire danger –animal migrations

Phenology Why Take Phenology Measurements –Estimates of greenness values from remote sensing data vary because of problems from atmospheric properties, sun angle, aging of satellite detectors. –GLOBE ground-based observations will help scientists validate estimates of growing seasons.

Phenology Green-Up and Green-Down Site Selection –Select native trees, shrubs or grasses. –Avoid sites near buildings or where watering or fertilization is done. –Select accessible sites.

Phenology Green-Up and Green-Down Site Selection –Select deciduous trees, shrubs or grasses. –Choose dominant over-story species. Green-up and green-down data from satellites affected mostly by these dominant species. –If over-story plants are evergreen conifers, use under- story broadleaf shrubs. –Try to use the same plants for green-up and green- down.

Phenology Green-Up and Green-Down Site Selection –If possible, choose a location close to the Atmosphere and Soil Moisture Study Sites. –Local topography can cause weather to vary even within short distances. –Keep the horizontal distance between Phenology and Atmosphere and Soil Moisture Study Sites less than 2 kilometers. –Keep the elevation difference less than 100 meters.

Phenology When are green-up observations made? –Twice weekly, starting at least two weeks before initial budburst until leaf length stops increasing. –Check with local sources for average green- updates to start observations.

Phenology When are green-down observations made? –Twice weekly, starting two weeks before initial green-down until leaf color change is complete or leaves fall off. –Check with local sources for average green- updates to start observations.