Research ArticleArticles

Evaluating Root Crown Excavation as a Treatment for Deeply-Planted Landscape Trees

Richard G. Rathjens, T. Davis Sydnor and David S. Gardner
Arboriculture & Urban Forestry (AUF) November 2009, 35 (6) 287-293; DOI: https://doi.org/10.48044/jauf.2009.043

Article Figures & Data

Tables

  • Table 1.

    Description of the Ohio root crown excavation experimental sites.

    LocationPlanting areaTree speciesNumber of treesAge of planting yearsPlant depth cm Mean (SD)
    CincinnatiStreet median stripShingle oak (Quercus imbricaria Michx.)3028.8 (3.5)
    CincinnatiStreet treeLacebark elm (Ulmus parvifolia Jacq.)2096.8 (3.5)
    DublinParkAsh species (Fraxinus spp.)400.516.2 (4.5)
    DublinParkMaple species (Acer spp.)400.520.3 (6.0)
    DublinParkBlue spruce (Picea pungens Engelm.)400.510.1 (6.0)
    StrongsvilleParking lot islandHoneylocust (Gleditsia triacanthos L. var. inermis (L.) Zab.)20613.7 (3.8)
    StrongsvilleStreet treeHoneylocust (Gleditsia triacanthos)20511.6 (3.3)
    StrongsvilleStreet treeHedge maple (Acer campestre L.)40117.7 (4.5)

    • SD = Standard Deviation.

  • Table 2.

    Name and taxonomic class of the soils in the Ohio root crown excavation experiment.

    LocationPlanting areaSoil nameTaxonomic class
    CincinnatiStreet median stripUrban land-Martinsville complexFine-loamy, mixed, active, mesic Typic Hapludalfs
    CincinnatiStreet treeUrban land-Stonelick complexCoarse-loamy, mixed, superactive, calcareous, mesic Typic Udifluvents
    DublinParkCrosby silt loamFine, mixed, active, mesic Aeric Epiaqualfs
    StrongsvilleParking lot island, Hedge maple street treeMahoning-Urban land complexFine, illitic, mesic Aeric Epiaqualfs
    StrongsvilleHoneylocust street treeUdorthents, loamyLoamy, mixed, mesic Typic Udorthents
  • Table 3.

    Growth, chlorophyll and stress measurements for the Cincinnati shingle oak trees with and without root crown excavation.

    Growthz/chlorophyll/stress measurementyTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2004 trunk diameter (cm)0.7 (0.4)0.6 (0.3)
    2005 trunk diameter (cm)1.0 (0.5)0.8 (0.3)
    2006 trunk diameter (cm)0.8 (0.5)0.7 (0.4)
    2007 trunk diameter (cm)0.7 (0.2)0.7 (0.2)
    2005 tree height (cm)32.5 (26.9)21.7 (25.1)
    2006 tree height (cm)22.3 (29.2)19.5 (35.0)
    2007 tree height (cm)53.9 (35.3)40.6 (34.0)
    2005 canopy width (cm)20.3 (27.4)15.2 (33.2)
    2006 canopy width (cm)36.5 (44.9)41.3 (37.0)
    2007 canopy width (cm)51.5 (38.1)44.0 (34.4)
    2003 twig extension (cm)8.3 (6.4)6.1 (5.6)
    2004 twig extension (cm)13.1 (10.9)14.2 (11.0)
    2005 twig extension (cm)10.2 (5.7)9.5 (4.8)
    2006 twig extension (cm)9.9 (5.8)10.4 (6.1)
    2007 twig extension (cm)9.5 (8.1)9.0 (4.4)
    2005 chlorophyll23.4 (8.2)25.2 (6.8)
    2006 chlorophyll24.4 (10.0)25.7 (9.0)
    2007 chlorophyll26.4 (10.4)21.7 (6.1)
    2007 leaf scorchx3.0 (1.8)3.1 (1.6)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance not significant at P < 0.05 or P < 0.01 for any measurement.

    • ↵x Scale of 1–5; 1 = brown leaves, 5 = green leaves.

    • SD = Standard deviation.

  • Table 4.

    Growth, chlorophyll and pest activity measurements for the Dublin blue spruce trees with and without root crown excavation.

    Growthz/chlorophyll/pest activity measurementyTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)1.0 (0.7)1.0 (0.6)
    2006 trunk diameter (cm)0.1 (0.1)0.1 (0.2)
    2007 trunk diameter (cm)0.5 (0.4)0.6 (0.6)
    2005 tree height (cm)35.0 (11.1)35.0 (26.6)
    2006 tree height (cm)18.3 (15.3)27.2 (22.4)
    2007 tree height (cm)25.9 (17.9)20.8 (17.7)
    2005 canopy width (cm)27.4 (19.5)19.8 (17.9)
    2006 canopy width (cm)9.1 (17.4)13.7 (18.4)
    2007 canopy width (cm)18.3 (18.2)15.2 (18.5)
    2004 twig extension (cm)9.5 (2.7)8.6 (3.2)
    2005 twig extension (cm)9.2 (2.2)9.4 (3.2)
    2006 twig extension (cm)8.9 (2.6)9.0 (3.4)
    2007 chlorophyll1.3 (0.4)1.2 (0.4)
    2004 mite injury (%)16.0 (17.5)24.2 (20.9)
    2006 bagworm (no.)18.6 (35.9)4.4 (7.5)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance not significant at P < 0.05 or P < 0.01 for any measurement.

    • SD = Standard deviation.

  • Table 5.

    Growth and chlorophyll measurements for the Strongsville honeylocust parking lot trees with and without root crown excavation.

    Growthz/chlorophyll measurementyTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)0.8 (0.2)0.8 (0.4)
    2006 trunk diameter (cm)0.4 (0.2)0.4 (0.2)
    2007 trunk diameter (cm)0.3 (0.2)0.7 (0.5)
    2005 tree height (cm)8.3 (14.2)10.1 (21.5)
    2006 tree height (cm)16.6 (28.4)33.8 (38.6)
    2007 tree height (cm)24.9 (35.5)13.5 (22.1)
    2005 canopy width (cm)27.7 (46.1)50.8 (37.3)
    2006 canopy width (cm)36.0 (38.1)27.1 (23.8)
    2007 canopy width (cm)2.7 (9.1)10.1 (21.5)
    2004 twig extension (cm)24.1 (12.6)23.6 (12.8)
    2005 twig extension (cm)13.4 (8.9)16.3 (12.9)
    2006 twig extension (cm)12.9 (9.3)11.2 (9.5)
    2006 chlorophyll23.7 (10.7)29.1 (12.7)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance not significant at P < 0.05 or P < 0.01 for any measurement.

    • SD = Standard deviation.

  • Table 6.

    Growth and chlorophyll measurements for the Strongsville honeylocust street trees with and without root crown excavation.

    Growthz/chlorophyll measurementyTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)0.7 (0.3)0.7 (0.3)
    2006 trunk diameter (cm)0.4 (0.2)0.5 (0.2)
    2007 trunk diameter (cm)0.4 (0.2)0.3 (0.3)
    2005 tree height (cm)27.1 (28.3)27.7 (21.3)
    2006 tree height (cm)40.6 (59.0)38.8 (65.5)
    2007 tree height (cm)6.7 (13.4)0.0 (0.0)
    2005 canopy width (cm)60.9 (54.9)66.5 (50.6)
    2006 canopy width (cm)6.7 (13.4)11.0 (15.3)
    2007 canopy width (cm)47.4 (37.6)38.8 (23.9)
    2004 twig extension (cm)26.4 (12.3)27.5 (11.4)
    2005 twig extension (cm)20.3 (9.7)17.8 (9.2)
    2006 twig extension (cm)23.8 (8.0)21.0 (8.0)
    2006 chlorophyll27.4 (9.3)24.3 (9.4)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance not significant at P < 0.05 or P < 0.01 for any measurement.

    • SD = Standard deviation.

  • Table 7.

    Growth, chlorophyll and stress measurements for the Dublin maple trees with and without root crown excavationz.

    Growthy/chlorophyll/stress measurementTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)0.6 (0.3)0.8 (0.7)
    2006 trunk diameter (cm)0.7 (0.3)0.6 (0.4)
    2007 trunk diameter (cm)0.1 (0.2)0.1 (0.2)
    2005 tree height (cm)13.6 (20.8)19.7 (22.6)
    2006 tree height (cm)17.6 (23.3)15.2 (23.1)
    2007 tree height (cm)20.9(21.4)16.0 (18.5)
    2005 canopy width (cm)13.6 (15.5)19.7 (14.8)
    2006 canopy width (cm)25.5 (23.2)19.7 (20.3)
    2007 canopy width (cm)15.1 (33.2)12.7 (25.4)
    2004 twig extensionx (cm)4.9 (3.8)8.0 (6.3)
    2005 twig extensionw (cm)5.1 (3.5)7.0 (5.6)
    2006 twig extension (cm)10.8 (8.5)8.8 (11.3)
    2005 chlorophyll14.7 (5.4)13.6 (4.9)
    2006 chlorophyll20.2 (7.2)19.0 (4.7)
    2007 chlorophyllx9.3 (5.5)15.1 (11.1)
    2004 early fall colorv4.0 (0.7)4.0 (0.7)

    • ↵z Root crown excavation included girdling root removal for approximately 20% of the trees.

    • ↵y Growth measurements except twig extension are increase in growth from the previous year.

    • ↵x Analysis of variance significant at P < 0.01.

    • ↵w Analysis of variance significant at P < 0.05.

    • ↵v Scale of 1–5; 1 = red leaves, 5 = green leaves.

    • SD = Standard deviation.

  • Table 8.

    Growth and chlorophyll measurements for the Strongsville hedge maple trees with and without root crown excavationz.

    Growthy/chlorophyll measurementTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)0.5 (0.4)0.6 (0.4)
    2006 trunk diameter (cm)0.3 (0.4)0.6 (0.5)
    2007 trunk diameter (cm)0.4 (0.3)0.6 (0.6)
    2005 tree height (cm)24.4 (18.7)21.3 (22.3)
    2006 tree height (cm)12.5 (18.8)13.7 (18.4)
    2007 tree height (cm)36.5 (32.9)27.1 (23.1)
    2005 canopy width (cm)25.9 (22.7)27.4 (27.7)
    2006 canopy width (cm)10.7 (18.4)24.3 (33.6)
    2007 canopy width (cm)24.4 (23.6)33.8 (38.9)
    2004 twig extension (cm)9.5 (8.4)10.8 (11.5)
    2005 twig extension (cm)19.9 (12.4)21.4 (13.3)
    2006 twig extensionx (cm)15.0 (12.8)21.3 (19.1)
    2006 chlorophyllw19.6 (5.1)23.7 (6.2)
    2007 chlorophyllw23.5 (6.4)28.0 (6.9)

    • ↵z Root crown excavation included girdling root removal for approximately 90% of the trees.

    • ↵y Growth measurements except twig extension are increase in growth from the previous year.

    • ↵x Analysis of variance significant at P < 0.05.

    • ↵w Analysis of variance significant at P < 0.01.

    • SD = Standard deviation.

  • Table 9.

    Growth and chlorophyll measurements for the Dublin ash trees with and without root crown excavation.

    Growthz/chlorophyll measurementTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)0.7 (0.3)0.9 (0.4)
    2006 trunk diameter (cm)0.6 (0.3)0.5 (0.2)
    2007 trunk diameter (cm)1.0 (0.9)0.9 (1.1)
    2005 tree height (cm)24.3 (18.7)31.9 (23.0)
    2006 tree height (cm)16.7 (20.8)21.2 (28.0)
    2007 tree height (cm)36.4 (21.1)33.4 (19.4)
    2005 canopy width (cm)18.2 (22.9)30.4 (22.0)
    2006 canopy width (cm)21.2 (17.3)15.2 (18.4)
    2007 canopy width (cm)25.8 (26.5)33.4 (23.9)
    2004 twig extension (cm)6.5 (4.5)5.6 (3.1)
    2005 twig extension (cm)8.5 (4.4)7.7 (6.2)
    2006 twig extension (cm)8.6 (7.6)6.5 (4.9)
    2006 chlorophylly37.8 (7.5)34.5 (8.7)
    2007 chlorophyll24.1 (8.5)25.0 (10.2)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance significant at P < 0.05.

    • SD = Standard deviation.

  • Table 10.

    Growth and chlorophyll measurements for the Cincinnati elm trees with and without root crown excavation.

    Growthz/chlorophyll measurementTreatment
    Excavation Mean (SD)No excavation Mean (SD)
    2005 trunk diameter (cm)1.9 (0.7)1.8 (1.3)
    2006 trunk diameter (cm)2.4 (3.4)0.8 (0.5)
    2007 trunk diameter (cm)0.8 (0.5)0.8 (0.6)
    2005 tree height (cm)2.7 (9.1)24.3 (34.6)
    2006 tree heighty (cm)155.4 (77.9)54.8 (79.7)
    2007 tree height (cm)6.10 (12.8)115.8 (173.4)
    2005 canopy width (cm)155.1 (63.1)118.8 (64.9)
    2006 canopy width (cm)57.9 (85.5)27.4 (33.5)
    2007 canopy width (cm)45.7 (45.9)36.5 (60.6)
    2004 twig extension (cm)17.3 (10.0)13.7 (7.1)
    2005 twig extension (cm)11.3 (4.5)12.1 (3.9)
    2006 twig extension (cm)9.2 (5.9)9.2 (5.6)
    2007 twig extensionx (cm)17.6 (7.6)13.4 (5.7)
    2005 chlorophyll33.6 (9.7)32.3 (11.8)
    2006 chlorophyll34.7 (12.7)31.3 (9.4)
    2007 chlorophyll29.7 (12.3)28.3 (7.2)

    • ↵z Growth measurements except twig extension are increase in growth from the previous year.

    • ↵y Analysis of variance significant at P <0.01.

    • ↵x Analysis of variance significant at P <0.05.

    • SD = Standard deviation.

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Evaluating Root Crown Excavation as a Treatment for Deeply-Planted Landscape Trees
Richard G. Rathjens, T. Davis Sydnor, David S. Gardner
Arboriculture & Urban Forestry (AUF) Nov 2009, 35 (6) 287-293; DOI: 10.48044/jauf.2009.043
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