Northern Research Station
11 Campus Blvd., Suite 200
Newtown Square, PA 19073
(610) 557-4132 TTY/TDD
Title: Tree and impervious cover change in U.S
Author: Nowak, David J.; Greenfield, Eric J.
Publication: Urban Forestry & Urban Greening. 11(1): 21-30.
Key Words: city trees, ecosystem services, forest monitoring, urban forestry, urban greening, urban trees
Abstract: Paired aerial photographs were interpreted to assess recent changes in tree, impervious and other cover types in 20 U.S. cities as well as urban land within the conterminous United States. National results indicate that tree cover in urban areas of the United States is on the decline at a rate of about 7900 ha/yr or 4.0 million trees per year. Tree cover in 17 of the 20 analyzed cities had statistically significant declines in tree cover, while 16 cities had statistically significant increases in impervious cover. Only one city (Syracuse, NY) had a statistically significant increase in tree cover. City tree cover was reduced, on average, by about 0.27 percent/yr, while impervious surfaces increased at an average rate of about 0.31 percent/yr. As tree cover provides a simple means to assess the magnitude of the overall urban forest resource, monitoring of tree cover changes is important to understand how tree cover and various environmental benefits derived from the trees may be changing. Photo-interpretation of digital aerial images can provide a simple and timely means to assess urban tree cover change to help cities monitor progress in sustaining desired urban tree cover levels.
This document is in PDF format. You can obtain a free PDF reader from Adobe.
Forest Service Home | USDA.gov | recreation.gov