Tree Cover Density
Tree cover density, Turkey 2012 (Source: GeoVille/EEA)
Tree cover density, also referred to as canopy coverage or crown cover, is defined as the proportion of the forest floor covered by the vertical projection of the tree crowns. Tree cover density products display the level of tree cover density in a range from 0 (no trees) to 100% (full canopy coverage).
Tree cover density is a major factor in evaluating the forest status and is an important indicator for forest management interventions. Furthermore, tree cover density information is an important parameter to determine forest above-ground biomass.
The analyses can be conducted with very high resolution optical satellite images or LiDAR– each having certain advantages.
Tree cover densities are modelled on a continuous scale combining with two different methods. For one method, spectral information is used to calculate the probability of each pixel belonging to a certain class (0-100%), whilst the other method utilities density functions from sample plots (based on in-situ reference data or very high resolution imagery) are used for site-specific calibration.
Known restrictions / limitations
In tropical forest areas frequent cloud cover can be an issue for the production of imagery. Density samples are required to generate tree cover density. Thus either sample plots are needed or (even though the density can be derived from lower resolution data (HR2)) the availability of VHR1 or VHR2 data must be ensured for the generation of density samples based on visual interpretation.
Lifecycle stage and demand
Geographic coverage and demand
Demand and coverage is global, especially in heavily forested areas.
Input data sources
Optical: HR1, HR2
Spatial resolution and coverage
Spatial resolution: 30- 100 m pixel size
Minimum Mapping Unit (MMU)
n/a (the product is directly based on the input data; the smallest unit is one pixel)
The minimum mapping width is between 10 to 30 m.
Accuracy / constraints
The accuracy of the maps is related to the annual/seasonal variability on ground as well as the possibility to use ground data to validate and update the map contents. The geometric accuracy is less than 1 pixel which in the case of tree cover density is on the order of 4-30 m (related to pixel resolution) and typically accuracies of 80–90% are reached for the classifications.
Thematic accuracy: 80-90%
Spatial accuracy: one pixel, but depends on reference data
Accuracy assessment approach & quality control measures
Stratified random points sampling approach utilizing VHR reference or other geospatial in-situ data. Statistical confusion matrix with user’s and producer’s accuracy as well as kappa statistics for tree cover density.
Frequency / timeliness
Observation frequency: The frequency is constrained by satellite revisit and acquisition timeframes, but also processing requirements. Depending on the requirements of the customer the best suitable satellite sensor has to be chosen considering spatial / spectral resolution as well as revisit frequency. For change monitoring, a baseline assessment is needed, which then can be followed by annual monitoring of revegetation/regrowth. Typically, long-term changes are detected on a 3 to 5 year basis (frequency can be lower or higher depending on demand).
Timeliness of deliverable: Depending on size of the mapped area, resolution, MMU.
VHR1 data must be commercially acquired.
Delivery / output format
|Peer Reviewer:||Hatfield Consultants|
Maria Lemper, Jan Militzer
Tree cover density
# of Pages:
Internal – Project consortium and science partners
External – ESA
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