Phenology
The seasonal cycle of vegetation growth and senescence, visible in satellite time series and used to separate real change from seasonal variation.
Phenology describes when plants leaf out, peak and senesce. In satellite records it appears as a repeating annual curve of vegetation indices, driven by rainfall, temperature and day length.
Understanding that curve is a prerequisite for change detection. A single image taken in the dry season can look like degradation next to a wet-season image of the same intact forest. Methods that model the expected seasonal signal — and flag departures from it — avoid a large class of false positives.
Phenology also informs project design. Planting windows, grazing rotations and harvest timing all depend on seasonal cycles, and monitoring plans must sample consistently within the same phenological window to keep measurements comparable year on year.
Frequently asked questions
How is phenology measured from space?
By tracking vegetation indices over time and fitting seasonal curves, then extracting metrics such as green-up date, peak value and senescence rate.
Can phenology reveal degradation?
Indirectly. Degraded forest often shows altered seasonality and lower peak greenness, which appears as a persistent shift in the fitted curve.