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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.

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Unri Deep Roots Webcast 08 Compressed

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