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Health of Street Tree Maples Report

Health and Incidence & Severity of Decay of Street Tree Maples in Four Upstate New York Cities (PDF) (1.1 MB)

Dr. Chris Luley, of Urban Forestry LLC, conducted research of wood decay in maples in upstate New York cities in 2006-2007. He recently reported his findings to the Department's Urban Forestry Program.

The research was made possible by a grant awarded by the ISA Hyland Johns Fund and by a smaller grant from the Department's Urban Forestry Program.

The Urban Forestry Program required three products be produced specifically for the NYS DEC foresters:

  1. slides on decay testing and evaluation methods for use in the DEC's existing "risk tree" training power point presentations which would complement and improve our existing training resource;
  2. a report on the "State of Health" of urban maples,
  3. and two one-day training sessions on decay testing and evaluation. Participants were able to learn how to "sound" for decay with the assistance of Dr. Luley.

The report provides the methodology in completing the research, and sections on Urban Tree Biological Health in New York and Urban Tree Structural Health and Decay in New York. Best of all, the results of the research have been compiled in an easy to read report available to the public.

Report Executive Summary

A random selection of street tree maples (Norway, silver, and sugar) and a random selection of "other species" in four diameter classes between 12 and 30+ inches were surveyed in Albany, Buffalo, Rochester, and Syracuse, New York for tree health, and decay incidence and severity. Based on city inventory data, maple species comprise over 54% of the total tree population, and Norway maple alone is over 36% of the total tree population. Many of these maples are mature to over mature as they have served as replacements for trees killed by Dutch Elm Disease.

Tree Health

In brief, the survey results indicate:

  • Trees in Rochester were in better condition trees compared to the other three cities.
  • On average, trees in were rated in fair or worse condition.
  • Larger diameter trees were in the poorest condition.
  • Over 50% of the large diameter Norway maples were rated in poor condition.
  • Sugar maples had the most dieback and highest percentage of poor condition tree across all tree diameter classes.
  • The selection of other species were rated in the best tree health condition across all diameter class.

Decay Incidence & Severity

In brief, the survey results indicate:

  • Rochester had the nearly the lowest incidence of decay, and the least percentage of severely decayed trees.
  • Decay incidence was found to be 57% overall and generally increased with increasing diameter class.
  • Decay incidence was over 50% even in smallest diameter trees (12-18 inches). However, only 2.5% of all trees were found to have severe decay (more than 70% of the radius decayed).
  • Incidence of severely decayed trees was greatest for silver maples and Norway maples.
  • Incidence of severely decayed trees was lowest for sugar maple and other species.
  • The incidence of severely decayed trees also increased with diameter class.

Study Implications

  • Larger diameter maples (greater than 25 inches in diameter) of all species will likely require increased levels of inspection, removal, and replacement going into the future due to their poor condition and increased amounts of decay.
  • The random selection of "other species" in the study was in better condition and had lower severity of decay, suggesting the diversity is a buffer against decay, and for tree health.
  • Well funded urban street tree programs like Rochester's may result in trees that are in better condition and have less decay. However, the influence of other factors such as weather events may also be important.

For the full report, click on the link at the top of this page.

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    Division of Lands and Forests
    Urban & Community Forestry Program
    625 Broadway, 5th Fl
    Albany, NY 12233-4253
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