Tree Canopy Assessment

Tree canopy (TC) is the layer of leaves, branches, and stems of trees that cover the ground when viewed from above. The City conducted its first tree canopy assessment in 2014 using satellite imagery collected in 2010. This assessment quantified existing canopy (image below) and outlined areas where increases in tree canopy could occur. With this information, the City hopes to establish tree canopy goals and monitor progress over time.

City-Wide Tree Canopy
The City of South Burlington’s Tree Canopy is highlighted in the above image.

Figure 1: Tree Canopy metrics based on % of land area covered by each TC type.An evaluation of the 2010 data indicated that approximately 33% of South Burlington is covered by tree canopy (graph to the right).  After accounting for areas within the City that are not suitable for additional tree canopy (e.g. recreation fields, solar panel arrays, the Burlington International Airport, etc.), it was determined that the tree canopy could be increased by as much as 49% . This potential 49% increase is predominantly located on residential property with very little existing tree canopy (see frequency histogram for residential property). The graph below shows the breakdown of existing and potential additional tree canopy within South Burlington’s different land uses.

Figure 10

Benefits of Tree Canopy

Tree canopy can provide many benefits to communities including:

  • Improved water quality
  • Energy saving
    • Lowering summer temperatures
  • Enhancing property values
  • Wildlife habitat
  • Aesthetics
  • Improved public health
    • Reduced air & noise pollution
  • Traffic calming, slower driving speeds, and safer sidewalks
  • Extends the life of roadways
  • Carbon sequestration

Trees and Stormwater

A robust tree canopy can assist the City with its goal to improve water quality in local streams and Lake Champlain.  Enhancing tree canopy throughout the City has the potential to:

Forest Hydrologic Cycle
Figure 2. Forest Hydrologic Cycle (Source: Federal Interagency Stream Restoration Working Group, 1998)
  • Help to reduce stormwater runoff amount and intensity (peak flows) through interception (see figure below) and improved infiltration.
  • Research has shown that for every 5% of additional tree canopy, stormwater runoff is reduced by approximately 2%.
  • Improve water quality through nutrient uptake.
  • Cool water temperatures before entering streams or infrastructure.
  • Protect soils from erosion.

The tree canopy analysis revealed that the stormwater impaired watersheds in South Burlington (Bartlett, Centennial, Englesby, Potash, Muddy, and Monroe Brooks) have significant potential for tree canopy growth.  Improving and increasing the City’s tree canopy in these areas has the potential to improve water quality in a cost effective way and reduce the City’s reliance on Capital Projects to achieve stormwater and Lake Champlain TMDL goals.

Example of tree canopy interception. Notice the dry pavement beneath the tree canopy.

Urban heat island effect – this analysis also showed a correlation between lower surface temperatures and areas with higher tree canopy coverage.

Landsat-derived surface temperatures: August 28, 2010




Last Updated: June 2014