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Why Are Urban Trees Dying?

A Case Study

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Pocket Woodlands®

Inspired by nature, backed by research.

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Background Research on Urban Trees

COMPACTED SOIL

  • Limits growth of roots Grabosky et al., 2009 

  • Restricts access to nutrients, oxygen and water Lou et al., 2010

AERATED SOIL

  • The most important factor in healthy development of urban trees Grabosky & Bassuk, 1995; Kopinga, 1991; Lindsey & Bassuk, 1992

SURVIVAL

  • 50% of trees will likely die in the first 20 years from planting Roman & Scatena, 2016

  • Trees in pits have a lower survival rate than trees in berms

Urban Trees in a Mid-Sized City

  • $400 per re-plant

  • Dead and dying trees

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ANNUAL BUDGET

NEW TREES
75% - 187 trees

  • $400 per tree (includes labour)

  • Cost of maintenance not included

TREE REPLACEMENT
25% - 63 re-plants

Case Study
Assessing health and future cost of urban trees

24 Kentucky Coffee Trees

Tree Planting - Pit vs. Berm

Same species, age & year planted
Different planting methods

Planting Methods

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Pits

  • Individual trees

  • Compacted soil

  • Hard surface covers roots

PitvsBerm-graphic_Berm.png

Berms

  • Groupings of trees

  • Raised and aerated soil

  • Includes shrubs, grasses, other vegetation

Conclusion

PitvsBerm-graphic_Pit.png

Pits

  • Less healthy 

  • Live shorter lives

  • Grow more slowly

  • Cost more to plant

  • Have greater long-term cost

PitvsBerm-graphic_Berm.png

Berms

  • Healthier 

  • Live full life span

  • Grow at natural rate

  • Less expensive

  • Create long-term savings

How Much Will It Cost The City To Continue To Plant Trees In Pits
Each tree will be replaced 4 to 5 times

Over $7million
IN 100 YEARS

Nearly 75% of the city’s 100-year budget of $10,000,000 will have been used for replacement trees

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