Monitoring weekly changes in phenology remotely across the western United States
Weekly updates from space provide insight into how well vegetation is growing in the United States.
Natural resource managers often schedule local management activities based on seasonal phases and need to monitor trends in drought and other vegetation reductions at the regional or national scale. Grazing, seed collection, tree planting, wildlife surveys, and application of biocontrol agents all need to occur at specific times during the growing season. Tracking regrowth following fires and other disturbances is also important for documenting ecosystem recovery.
Four maps of the United States showing PhenoMap outputs for 2005, 2011, 2013, and 2015, with wide variability between years. PhenoMap weekly percentile images for week 26 (early July) for the years 2005, 2011, 2013 and 2015 demonstrate the wide variation in phenology between years.
Satellite data can provide weekly updates of phenology (NDVI, a measure of “greenness”) at a resolution of 15 acres. The PhenoMap web map was created to place these “greenness” images in an interactive format for managers to view local and regional changes in phenology. PhenoMap also helps to place current values of greenness in a historical context so managers can understand how this year’s current greenness compares to previous year greenness values.
In order to see how well the satellite data was capturing “green-up” and “brown-down,” satellite data was compared to cameras capturing changes in phenology in the various vegetation types of the western United States.
PhenoMap, an interactive web map, can be used by any manager, agency, scientist, or entity that would like to track the phenology of small pastures or larger regions. PhenoMap effectively tracks phenology of grassland, shrublands, deciduous broadleaf, and mixed forest ecosystems. PhenoMap has a more difficult time tracking green-up changes in evergreen needleleaf systems due to the large amount of year-round green foliage in these vegetation types.