Arizona Envirothon 2015

Urban/Community Forestry

Scientific Articles

AZ Envirothon

Scientific articles can be excellent sources of actual data and broad concepts about an environmental issue. Scientific articles are usually peer reviewed by independent experts. Peer review doesn't necessarily guarantee that articles are free of errors, but it does lend substantial credibility to an article. Scientific articles range in scope from general reviews of an issue to specific research studies about a very small part of an issue. The links below cover that full range.

Note for teachers and coaches: These articles are not terribly tough academically relative to typical science articles, but some do contain sections of statistics, etc., that could be difficult for high schoolers. It might be best for you to read these articles first and highlight the need-to-know stuff while blocking out gory details of methods and quantitative analyses.

The articles:

Benefits and Costs of Urban Forestry

Carbon and Urban Forestry

It's commonly stated that trees should be planted to sequester (suck up and store) atmospheric CO2. Fine: trees do inhale CO2, and wood is upwards of 40 to 50% carbon. However, just how effective are urban forests at making a dent in the issue of increasing atmospheric CO2?

  • Some basic plant ecology: Can you explain the grand carbon equation of life?

    carbon equation

    1. Green plants (ag crops, trees, cactus, you name it) take this equation in both directions, right and left. In which direction would it be called photosynthesis? Respiration?
    2. Do you participate in this equation? If so, when? Which direction?
    3. By the way, be careful with the big numbers for carbon (C) versus carbon dioxide (CO2). CO2 (mw = 44) is 3.67x heavier than C (aw = 12).
  • Carbon storage and sequestration by trees in urban and community areas of the United States: Numbers on just how important urban forests are for sequestering atmospheric CO2. Surprising.
  • Quantifying the Role of Urban Forests in Removing Atmospheric Carbon Dioxide: More numbers how much can be by individuals (you) to sequester atmospheric CO2. Surprising.
  • Click here for up-to-date numbers on CO2 emissions in the US.
  • Click here for up-to-date numbers on CO2 emissions globally.
  • The American Elm Story
    American elm was arguably the finest urban tree species of all in the US. Planted extensively, it graced Main St. America nearly everywhere. Then, in the early 1930s, a fungus from Europe was introduced onto this continent, and, transported by beetles, it decimated the entire species. Known as Dutch elm disease, it completely altered urban forests. Academic discussion of urban forestry is not complete without knowing the American elm story.
    US Forest Service photo
    • The American Elm: This 1930s publication details what was happening early in the Dutch Elm crisis. Nice pictures and poetic text. No need to read all of this, but enjoy relevant sections. Also, translate this experience to what you know of urban forestry today in Arizona. Can this "national catastrophe" (page 29) be avoided nowadays?
    • American Elm Restoration: An example of modern efforts to restore American elm. Any application of this strategy to urban forestry in Arizona?

    Laboratory of Tree-Ring Research, University of Arizona
    Tucson, Arizona 85721 USA
    Main Office: (520) 621-1608, Fax: (520) 621-8229
    Comments to Paul Sheppard: sheppard @