Letter: Planting trees and mistletoe.

As an ecologist in Tucson for 53 years, I comment on Gerry Maggiora’s recent letter about the City of Tucson’s plan to plant a million trees. Shady, tree-lined streets is an eastern U.S. vision that is inappropriate for desert areas dependent on dwindling Colorado River water. One reason given to plant trees is that shade slows down global warming. In the Sonoran Desert, most of the shade is from shrubs, not trees. I need to point out that mistletoes do not kill trees. The desert mistletoe (Phoradendron californicum) is a hemiparasite that only draws a bit of water and no nutrients from the tree and produces its own energy. Trees die from other causes such as lack of water, Texas root rot, and wind fall. Mistletoes have provided food and nest sites for Phainopeplas and many other birds in the velvet mesquites in my yard for over 35 years without harm.