Transcript Phenol - globe.unh.edu

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 CO2 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:
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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 understory broadleaf shrubs.
– Try to use the same plants for green-up and greendown.
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 greenupdates 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 greenupdates to start observations.