Should We Consider Expected Environmental Benefits When Planting Larger or Smaller Tree Species?

Abstract

Ohio, U.S.’s Shade Tree Evaluation Project began in 1965. Two of the original plantings in Brooklyn, Ohio, U.S. included 17 smaller growing, Lavalle hawthorn (Crataegus × lavallei Herincq ex. Lavallee) and 84 larger growing thornless honeylocusts (Gleditsia triacanthos L. Sunburst). One consequence of selecting trees is the differing values of environmental benefits generated by trees of various sizes and survival rates. Values of environmental benefits have not been considered in plant selection but the i-Tree free suite of software now allows this to be calculated. Algorithms recovered from i-Tree Streets were used to calculate environmental benefits in ten, randomly selected trees in each of the two plantings in Brooklyn, and adjusted for survival rates, 89% survival on Morton Avenue for honeylocusts and 65% for hawthorns as planted on Orchard Grove. When adjusted for survival, honeylocusts deliver USD $430 per tree in benefits in contrast to the $57 per tree for hawthorn. When viewed on a per surviving tree basis, honeylocusts provide more than 7.5 times the environmental benefits. Regardless of how it is viewed there is a significant reduction in environmental benefits when using smaller statured trees compared with larger trees. Communities should consider this aspect when space for larger trees is available.