Canopy Cover

Map of change in average percent canopy cover from 2001 to 2011 by HUC-14 in the Raritan Basin

Trees provide valuable benefits and contribute to the beauty of the Raritan region.  They add value to our property, filter the air, provide oxygen, cool our homes and neighborhoods in the summer, block the wind to reduce our heating costs in the winter, capture and filter runoff to protect our streams, sequester carbon from the atmosphere, provide wildlife habitat, provide recreational opportunities, and enhance our mental and physical health and sense of well-being.

In Volume 1 we explored the trends in upland forest areas for various time ranges between 1986 and 2012 and quantified net gains and losses of upland forest to other land uses.  In that analysis, upland forests lost 8,369 acres to other land uses basin-wide between 1986 and 2012.

In this analysis we utilized national landcover data sets to summarize the percent canopy cover across the Raritan Basin and by HUC-14 for 2011 and also calculated a change in canopy cover by HUC-14 for the ten years from 2001 to 2011. Think of canopy cover as the percent of a unit area on the ground that is covered by a canopy of trees or shrubs. While forest areas generally have high percent canopy cover (i.e. upwards of 75%), even urban areas with street or backyard trees will have some amount of measurable canopy cover.

Tree canopy covers approximately 40% of the Raritan Basin.  While canopy cover as a whole increased slightly across the basin, headwater regions showed a general decline in canopy cover.   The Emerald Ash Borer is expected to decimate nearly 10% of the region’s canopy cover over the next decade.

Read more about Canopy Cover starting on page 7 of the State of the Raritan Report, Vol. 2