by DJ Nowak, MH Noble, SM Sisinni, JF Dwyer
Journal of Forestry 99 (3):37–422001
This article summarizes the results of the first national assessment of urban forests in the United States (Dwyer et al. 2000; https://www.treesearch.fs.fed.us/pubs/29448). The importance of urban forests is described. The methods for estimating both the tree canopy cover and the tree population are summarized, and major results are presented for the country as a whole and in regional terms. The large regional variation in urban tree cover (from 55% in Georgia to 3.6% in Wyoming) could be explained in terms of three main variables: ecoregion (i.e., the amount of natural forest cover), population density (greater density equals fewer trees), and land use. The study estimates the number of trees in urban areas at 3.8 billion, much higher than an earlier estimate of 660 million, which was based on the assumption that there were 10 non-street trees for every one street tree. National implications of urban expansion on forests are discussed.