Let’s Diversify Community Forests

When reflecting on his state’s historic loss of elm trees, Dr. John Ball of South Dakota State University told The Forestry Source, a publication of the Society of American Foresters, “I realized we learned the wrong lesson. The lesson we learned was not to plant elms. What we should have learned was to diversify.” 

That important lesson means not simply switching to another species that is immune to a current plague, but rather to truly diversify the trees being planted. To ensure maximum effectiveness and maximum protection of the benefits provided by the urban forest, the diversification needs to be carefully planned. 

Urban forest diversity has been defined by Professor Emeritus Joe McBride of the University of California–Berkeley as “the complexity of tree species composition, the size distribution of trees, and the patterns of distribution within an urban forest.” With the continuing spread of urbanization and in the face of climate change, the concept — and practice — of tree diversification is more important than ever.