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Unri Deep Roots Webcast 08 Compressed

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Research update on best planting practices from the University of Minnesota.

Research update on best planting practices from the University of Minnesota.

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  • 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
  • 4. Some Average Life Spans
    • Bur Oak 250+ Years*
    • Silver Maple 125+ Years*
    • Boxelder 100+ Years*
    • Jack Pine 80+ Years*
    • Paper Birch 65+ Years*
    • Ford F150 Truck 20+ Years**
    • Urban Core Tree 7-10 Years***
    *Silvics of North America. **I Hope. ***Kielbaso, 1989
  • 5. State of the Urban Forest – 1989 J.J. Kielbaso
    • Average Tree Lifespans
      • “ Downtown” Urban Trees: 7-10 years.
      • Suburban Landscape Trees: 30-40 years.
      • Rural Landscape Trees: 60-70 years.
      • Native Undisturbed Sites: 150 years.
  • 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
  • 29. Effects on Landscape Lives
    • Predisposition to other problems
    • Stunted growth
    • Premature death/failure
    • Reduced ability to compartmentalize
  • 30. A Survey of Practitioners : North American Members of ISA (1998, n = 282)
    • Regarding Stem Girdling Roots and Tree Loss, Practitioners Stated:
    • Relationship to tree decline and death - 82% of the time.
    • Relationship to the sudden failure of trees – 18% of the time
  • 31. Predisposed Health
  • 32. Predisposed Health
  • 33. Predisposed Health
  • 34. Reduced Ability to Compartmentalize
  • 35. Premature Death
  • 36. Premature Failure in Loading Events
  • 37. Three “Deep Root” Studies
    • Frequency of Buried Root Systems.
    • Stem Girdling Roots & Storm Failures.
    • Correcting Pot-Bound Root Systems.
  • 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”
  • 40. Depth of Soil Over Tree Roots: A Survey of 5 Landscape Species
    • Range of Soil Depths over Roots
    • Condition of Canopies and Stems
    • Frequency, Extent, Location and Impact of Encircling or Stem Girdling Roots
  • 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
  • 42. Depth of Soil Over Roots: Survey Protocol
    • 3-9” d.b.h. Trees
    • Surveys included two teams.
    • 1 st Team “blind” condition rated
    • canopies and stems
    • 0-4 Rating System
  • 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
  • 44. Condition Rating: Canopies
    • 0-4 Rating System:
      • 0 = Dead
      • 4 = No obvious defects.
    • Canopy condition rating factors:
      • Characteristic density for the Species,
      • Live crown ratio (60% standard),
      • Crown symmetry,
      • Dieback.
  • 45. Condition Rating: Canopies E.g., Greenspire Littleleaf Linden to the right. Canopy condition reduced due to density.
  • 46. Condition Rating: Stems
    • Factors :
      • Lost Bark/Living Cambium,
      • Cracks/Ribs,
      • Decay,
      • Contributing Agents.
      • Stem Girdling Roots (above ground)
    • 0-4 Rating System:
      • 0 = No living cambium in stem,
      • 4 = No obvious defects.
  • 47. Condition Rating: Stems Dead Cambium Frost Crack
  • 48. Depth of Soil over Roots Surveys: Root Collar Exams
    • 2 nd Team performed root collar examination:
    • Data Recorded :
      • Depth to first order roots,
      • Frequency and location of
      • Stem Encircling Roots (SERs) and Stem Girdling Roots (SGRs),
      • % of stem affected.
  • 49. Depth of Soil over Roots Surveys: Root Collar Exam Protocol
    • Typical tools for root depth evaluations:
    • Surveyor’s arrow
    • Hand tools
    • Wet/Dry vac
    • Air knife
  • 50. Summaries
    • Majority Had > 1” Soil Over Roots*
    • Tilia, Acer and Fraxinus Worst: > 90% w/4”+
    • 1”+ Soil = More SER’s
    • Most Vulnerable Species: Tilia, Celtis, Fraxinus
    • Worst Condition Rating:Soil Depth – Tilia, Acer, Fraxinus
    • Most Common SGR’s:Soil Depth – Tilia, Fraxinus, Celtis, Acer
  • 51. What IS Too Deep?
    • Frequency of Stem Encircling Roots:
      • 1-3 Inches*
    • Frequency of Stem Girdling Suckers:
      • 5 Inches**
    • Frequency of Stem Girdling Roots:
      • 1-3 Inches*
    *Sugar Maple, Green Ash, Littleleaf Linden, Hackberry, Honeylocust **Littleleaf Linden
  • 52. What IS Too Deep?
    • Negative Effects on Health?
      • Species Dependent.
      • 1-3.5 inches was Too Deep.
      • Johnson and Johnson, 1997 Johnson and Borst, 1999 Johnson and Hauer, 2000 Johnson, et al., 2006. Planting Depth Interim Report.
  • 53. Where it Began?: Containerized Depth Problems
  • 54. Too Deep? Assume That It Is
  • 55. How Often Does it Happen?
    • 881 Trees Sampled out of 5500 Total
    • B&B and Containerized
    • 87%: Stem Buried 2+ Inches
    • 50%: Stem Buried 4+ Inches
    *Minneapolis Park and Recreation Board; St. Paul Division of Forestry Nursery Stock Survey 2001-2002*
  • 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
  • 63. Storm Damage in Minnesota: 1995-2005 n=1584
    • Total Failures (Trees failed at or below ground line) Was Most Common Damage Category = 54% of all damage,
    • The presence of SGRs was the most common pre-existing condition (32%).
  • 64. What IS Too Deep?
    • Impact On Storm Damage to Trees?
      • Most common reason for total failure: Buried SGRs.
      • Species dependent.
      • 1-4 inches.
      • Johnson, 2006. “Storm Damage in Minnesota, 1995-2005.”
  • 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
  • 70. Storm Damage in Minnesota: Failures due to Stem Girdling Roots 1995-2005 n=1584
    • 32% of all tree failures , located on the edges of storms
    • 26% of all boulevard total tree failures (53% of 6-10” category)
    • 68% of Little-leaf Lindens that failed in boulevards (#3 rd most common species)
    • > 90% of trees that had SGRs had stems buried 4” or more.
  • 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
  • 73. Stem Girdling Suckers!
    • University of Minnesota Planting Depth Study 2000-2007
    • Lindens at 5” depth = Higher Frequency of Suckering.
    • Higher Frequency of Suckering = Stem Girdling Suckers and Higher Mortality Rate
  • 74. Stem Girdling Suckers!
  • 75. Stem Girdling Suckers
  • 76. Stem Girdling Suckers
  • 77. Correcting Pot-Bound Root Systems
    • Study One:
      • 14 month experiment.
      • 2 species (Tilia and Salix).
      • 3 Treatments (slice, butterfly and “tease”).
      • No statistical differences between treatments and controls on survival (100%) and root production.
      • Arboriculture & Urban Forestry, Volume 33, Issue 1, January 2007.
  • 78. Correcting Pot-Bound Root Systems
    • Study Two:
      • Five years.
      • Four species: Acer platanoides, Acer x freemanii, Thuja occidentalis, Malus sp.
      • Two treatments: slicing, “boxing.”
      • Data: survival, condition ratings, caliper increase, root production.
  • 79. Correcting Pot-Bound Root Systems
    • Complete randomized block design.
    • Control and 2 treatments.
    • 8 replicates.
    • 11-05 to 11-10 study.
  • 80. Correcting Pot-Bound Root Systems “ Boxing” Control Scoring
  • 81. Correcting Pot-Bound Root Systems
    • Results to Date (08-08-08):
      • Mortality Rates: Controls:0; Slice Treatment:0; Boxing Treatment:0.
      • Condition Rating: No significant differences.
      • Growth Rates: No significant differences.
  • 82. Other Research?
    • Douglas Airhart – Tennessee Tech U.
    • Bonnie Appleton – VA Tech.
    • Mike Arnold – Texas A & M
    • Susan Day – VPI
    • Donna Fare – U. S. National Arboretum
    • Ed Gilman – U of Florida
    • Christina Wells – Clemson University
  • 83. Other Research?
    • J. Roger Harris, VPI
    • Gary Watson, Morton Arboretum
    • David Williams and Gary Kling, U of IL
    • T. Davis Sydnor and Richard Rathjens, Ohio State University
  • 84. Other Research?