The document discusses research on dysfunctional root systems and their impact on the lifespan of trees in urban and landscape settings. It finds that trees with abnormal or pot-bound root systems are more likely to experience issues like stem girdling roots, reduced ability to compartmentalize damage, and premature death. Studies show trees with soil over their roots more than 1-3 inches thick are also more prone to problems and storm damage failure due to stem girdling roots. Correcting pot-bound root systems through techniques like slicing or boxing can help reduce these risks.

1. DEEP ROOTS RESEARCH UNRI Webcast – 08/13/08 “ Dysfunctional Root Systems and Brief Landscape Lives” Gary Johnson, Department of Forest Resources, University of Minnesota

2. University of Minnesota Urban Forestry and Horticulture Institute Chad Giblin, Research Scientist Jeff Gillman, Associate Professor Dave Hanson, Research Specialist Gary Johnson, Professor and corresponding presenter. [email_address] , 612-625-3765. Rebecca Koetter, Research Fellow Patrick Weicherding, Ext. Educator and Professor

3. University of Minnesota Urban Forestry and Horticulture Institute

6. “Downtown” Urban Trees

7. “Suburban” Landscape Tree

8. “Rural” Landscape Tree

9. Native Undisturbed Sites

10. What’s a “Normal” Root System? 5 month root system from seed (butternut)

11. 6 year sugar maple root system from seed

12. Approximately 20 year old root system of linden

13. White spruce root system Pat Bartlett – Bartlett Forestry

14. What are “Normal” Roots? Seed Propagated Roots

15. “ Normal” Roots: Adventitious Roots

16. Abnormal Root Systems Root systems that deviate from normal or average root systems.

17. Balled and Burlapped

18. Containerized Root Systems

19. Plug Trays

20. J-Roots

21. Boulevards, Medians, Planters

22. Boulevards, Medians, Planters

23. Dysfunctional Root Systems Roots in unhealthy interactions within a plant system.

24. Dysfunctional Root Systems Buried root system growing to surface

25. Dysfunctional Root Systems Stem Encircling Roots

26. Dysfunctional Root Systems Stem Girdling Roots

27. Dysfunctional Root Systems Stem Girdling Roots and Stem Girdling Suckers

28. Dysfunctional Root Systems Pot-Bound Root System

31. Predisposed Health

32. Predisposed Health

33. Predisposed Health

34. Reduced Ability to Compartmentalize

35. Premature Death

36. Premature Failure in Loading Events

38. Frequency of Buried Root Systems in the Landscape

39. Decline in Canopy Condition Associated with SGRs and Tilia. July 7, 2006. Tilia cordata “Greenspire”

41. Depth of Soil over Roots Surveys: Sites and Selection Minneapolis 1997 - Acer saccharum , 1999 - Fraxinus pennsylvanica , 1999 - Tilia cordata , Rochester 2001 - Celtis occidentalis , Saint Paul 2004 - Gleditsia triacanthos N = 100 (+/-)Per Species, Randomly Selected

43. Criteria for Condition Rating Trees: Canopy and Stem Conditions ~ 10% cambial loss. One crack and/or one seam. 3.0 ~ 10-25% Dieback, or Loss of Density, or <50% L.C.R., or Loss of Symmetry. No cambial loss*. No decay. No cracks/seams. 4.0 No Dieback. Characteristic Density for the species. 60%+ Live Crown Ratio (L.C.R.). Symmetrical. Stem Pts Canopy

45. Condition Rating: Canopies E.g., Greenspire Littleleaf Linden to the right. Canopy condition reduced due to density.

47. Condition Rating: Stems Dead Cambium Frost Crack

53. Where it Began?: Containerized Depth Problems

54. Too Deep? Assume That It Is

56. Why Does it Happen? To Stabilize Trees in Containers.

57. Does it Work? No!* 2002 University of MN/Bailey Nursery Experiment 4 Tree Species, 460 Trees Total 4 Planting Depths: 0 – 2 – 4 – 6 Inches Results? All Leaned at Same Rates

58. Storm Failure Research: Most common pre-existing conditions

59. Storm Failure Triangle Tree Condition and Defects Loading Event wind, ice, snow Site Characteristics Failure Potential Gary Johnson, University of MN

60. Storm Failure: pre-existing conditions

61. Storm Failure: pre-existing condition

62. Premature Failure in Loading Events* III. Most common pre-existing conditions : For all damage, separating preexisting conditions : CONDITION % OF TOTAL Decay Only 13 Stem Girdling Roots (SGR) 12 Included Bark Only 4 Root Problems (other than SGR) 3 Codominant Leaders Only 4 Construction Damage Only 1 *Storm Damage 1995-2005; University of Minnesota

65. When Roots and Stems Conflict Soil Line SGR compression point

66. Layers of Stem Girdling Roots: Tilia

67. Soil Line SGR Compression

68. Storm Damage in Minnesota: SGRs below ground with compression Norway Maple ( Acer platanoides )

69. Storm Damage in Minnesota: 1998 n=564 1995-2005 n=1584 Total Tree Failures In Boulevards Most Commonly Damaged Size (d.b.h.) ranges 1998 1995-2005 Size (d.b.h.) Range % of Total % of Total 6-10 inches 28.6 29.0 >25 inches 25.7 26.0 20-25 inches 15.7 16.0 10-15 inches 14.3 14.0 15-20 inches 14.3 14.0

71. Storm Damage in Minnesota: 1998 n=564 1995-2005 n=1584 Commonly Damaged Species with Chronic Problems 1998 1995-2005 Little Leaf Lindens: 73% of all 76% that failed were 4”+ deep and had stem girdling roots causing stem compression. These trees failed below the stem compression points.

72. Decline in Stem Condition Associated with SGR’s and Tilia

74. Stem Girdling Suckers!

75. Stem Girdling Suckers

76. Stem Girdling Suckers

80. Correcting Pot-Bound Root Systems “ Boxing” Control Scoring

84. Other Research?