August 10, 2011

Tree Walk: 13 Endangered Shade Trees at Washington Square Village playground

If the NYU 2031 plan is approved as is, the playground at Washington Square Village will be demolished to build a temporary gym and then a permanent academic building. The plan is available at http://www.nyu.edu/nyu2031/nyuinnyc/growth/the-plan.php. Among other losses if this construction occurs, will be the loss of 13 large-stature shade trees: two honeylocusts, five Norway maples, and 6 London planetrees. The trees provide extensive shade to an area that receives sun for most of the day.

Image: Washington Square Village playground.  Note that there are London planetrees outside the playground on its western and eastern boundaries.

The diameter-at-breast-height (in inches) of each tree is as follows:

Honeylocust 1 (northernmost): 18.5"
Honeylocust 2: 16.25

Norway maple (northernmost) 1: 16.7"
Norway maple 2: 16.25
Norway maple 3: 19.25
Norway maple 4: 17.75
Norway maple 5: 15

London planetree (northernmost) 1: 19.75"
London planetree 2: 19
London planetree 3: 15.5
London planetree 4: 18.5
London planetree 5: 18.5
London planetree 6: 20.25


The approximate ecosystem benefits provided by each tree were calculated using i-Tree Design, a USDA Forest Service tree benefits calculator available at http://www.itreetools.org/design.php.  I classified the maples and planetrees as in good condition while I categorized the honeylocusts as in fair condition because past pruning has reduced their natural crown.

You can also use the predecessor of i-Tree Design, the National Tree Benefits Calculator developed by Casey Trees and Davey Tree Expert Co. This calculator, available at http://www.treebenefits.com/calculator, provides property value information. It also provides energy information based on your input of land use type while i-Tree Design uses building age and other criteria to generate its energy calculations.

Below I have provided a mix of gross and specific information for each tree.

Honeylocust 1: 18.5"
$37 in overall annual benefits
$12.17 in air quality benefits
$12.01 in stormwater benefits = interception of 2, 413 gallons of stormwater this year
$1.80 in carbon benefits
At 23.5 inches in diameter, this honeylocust will provide $48 in annual benefits.

Honeylocust 2: 16.25
$32 in overall annual benefits
$14.47 (air quality)
$16.16 (stormwater)
$1.51 (carbon)

Norway maple 1: 16.7"
$26 in overall annual benefits
$12.17 in air quality benefits
$12.01 in stormwater benefits
$1.80 in carbon benefits

Norway maple 2: 16.25
$25 in overall annual benefits
$11.83 (air quality)
$11.45 (stormwater) = interception of 1,432 gallons of stormwater this year
$1.17 (carbon) = removal of 593 pounds of carbon this year
If this maple grows to 21.25 inches, it will provide $35 in annual benefits.

Norway maple 3: 19.25
$31 in overall annual benefits
$13.84 (air quality)
$14.77 (stormwater)
$2.22 (carbon) = removal of 726 pounds of carbon this year (Did you know that one person flying from NYC to LAX generates 1,400 pounds of CO2?)

Norway maple 4: 17.75
$28 in overall annual benefits
$12.84 (air quality)
$13.11 (stormwater)
$1.97 (carbon)
If this maple gains 5 more inches in diameter, it will provide overall annual benefits of $38.

Norway maple 5: 15
$23 in overall annual benefits
$11 (air quality)
$10.07 (stormwater)
$1.50 (carbon)

London planetree 1: 19.75"
$36 in overall annual benefits
$15.13 in air quality benefits
$18.93 in stormwater benefits
$1.84 in carbon benefits

London planetree 2: 19
$34 in overall annual benefits
$14.64 (air quality)
$18 (stormwater)
$1.77 (carbon)

London planetree 3: 15.5
$23 in overall annual benefits
$11 (air quality)
$10.07 (stormwater) = interception of 1,705 gallons of stormwater this year
$1.50 (carbon) = reduction of 473 pounds of carbon this year
At 20.5 inches, this planetree would provide $37 in overall annual benefits.

London planetree 4: 18.5
$33 in overall annual benefits
$14.29 (air quality)
$17.38 (stormwater)
$1.72 (carbon)

London planetree 5: 18.5
$33 in overall annual benefits
$14.29 (air quality)
$17.38 (stormwater)
$1.72 (carbon)

London planetree 6: 20.25
$37 in overall annual benefits
$15.46 (air quality)
$19.56 (stormwater) = interception of 2,445 gallons of stormwater this year
$1.89 (carbon) = reduction of 604 pounds of carbon this year

These 13 trees currently provide $398 in overall annual benefits to the block, the neighborhood, and the city, and I have not calculated energy savings and aesthetic (property) values.  Also, there are 17 crabapples and hawthorns for which I did not take any measurements.  These understory trees support birds, squirrels, and insects.  This is not to say that the honeylocusts (see http://www.plant-materials.nrcs.usda.gov/pubs/etpmcfs8420.pdf), Norway maples, and London planetrees do not support wildlife, only that I often observe wildlife use of the shorter canopy trees. Finally, the trees in the playground provide (as yet) immeasurable pyscho-social benefits!

3 comments:

  1. great, thorough post- love it!

    ReplyDelete
  2. Thank you, Gillian.

    (Creating this post has made me consider enrolling in a graphic design class. I could make a more dramatic, visual statement if I had proper design skills.)

    ReplyDelete
  3. Excellent!
    Here in Porto Alegre, Brazil, could save many trees from Gonçalo de Carvalho street. Many still do not understand the benefits of urban trees ...

    ReplyDelete

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