HomeMy WebLinkAboutArborist Report
Protected Tree Report:
Tree Survey, Encroachment,
Protection and Mitigation
603 W. Camino Real Avenue
Arcadia, CA 91007
Prepared For: Mr. Vincent Yan
SD Design, Inc.
5401 Baldwin Ave.
Temple City, CA 91780
Tel: (626) 782-7915
Email: vincent.yan@signetdesigncorp.com
CDSG@gmail.com
Prepared By: Michael Crane
Arbor Care, Inc.
1660 E. Mountain St.
Pasadena, CA 91104
Tel: (626) 737-4007
Email: info@arborcareinc.net
February 2019
Table of Contents
Summary of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Background and Purpose of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Project Location, Description & Tree Ordinance . . . . . . . . . . . . . . . . . . . . . . . . 2
Tree Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Tree Characteristics & Health Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Construction Impact Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Design Analysis of Protected Tree Encroachments . . . . . . . . . . . . . . . . . . . . . . . 7
Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Appendix A - Photos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix B – Planting Trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Author’s Certifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Certification of Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Topographic Site Plan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pocket at back
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
1
SUMMARY OF DATA
BACKGROUND & PURPOSE
I was retained by the Designer and Project Manager, Mr. Vincent Yan, to be the consulting
arborist for the planned redevelopment of the property located at 603 W. Camino Real Ave.
There are Protected Trees located both on the property and off-site with a portion of the dripline
extending over the property. The proposed construction will encroach these trees and this report
will serve to both notify the City of Arcadia Planning Division of the extent of the impacts as
well as to inform the builder of the proper protection measures which must be taken in order to
preserve the trees. As part of my preparation for this report I made a site visit to the property on
January 30, 2019. I met with Mr. Yan at that time to view and discuss the proposed construction
plans as they relate to the preservation of the Protected Trees.
Total number of healthy Protected Trees on property including street trees
located in the adjacent public right-of-way area . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Total number of off-site Protected Trees
with canopies (driplines) encroaching onto the property . . . . . . . . . . . . . . . . . . . . 1
Total number of diseased/hazardous Protected Trees on site
proposed for removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Total number of healthy Protected Trees to be preserved . . . . . . . . . . . . . . . . . . . 1
Total number of healthy Protected Trees to be removed . . . . . . . . . . . . . . . . . . . 2
Total number of Protected Trees that will be preserved, which will
be impacted by construction within dripline (encroached) . . . . . . . . . . . . . . . . . . 1
Total number of Protected Trees with no dripline encroachments . . . . . . . . . . . 0
Total number of proposed mitigation trees to be planted on site . . . . . . . . . . . . . . 4
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
2
PROJECT DESCRIPTION & TREE ORDINANCE
This aerial view (courtesy of Apple Maps) has been illustrated to show the
approximate boundary lines (orange). The locations of the Protected Trees are
numbered in yellow.
The property consists of a one story single-family residence that appears to be in poor condition.
The home will be demolished and the property redeveloped into another one story single family
home.
The landscape is minimally maintained and the woody plants and trees are in various
conditions. The Protected Trees are also in various conditions. The landscape will be
renovated and the Protected Trees will be removed and replaced.
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Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
3
City of Arcadia Tree Ordinance
Oaks, Sycamore, and many other tree species are Protected under the various tree
ordinances. Here is a summary of the tree protection laws.
On January 21, 1992 the City Council adopted Ordinance No. 1962 recognizing oak trees as significant aesthetic
and ecological resources and establishing criteria for the preservation of oak trees. The regulations (Chapter 7 of
the Arcadia Municipal Code) provide that the following oak trees shall not be removed, relocated, damaged, or
have their protected zones encroached upon unless an Oak Tree Permit is granted:
• Engelmann Oaks (Quercus engelmannii) or Coast Live Oak, California Live Oak (Quercus agrifolia)
which have a trunk diameter larger than four (4) inches measured at a point four and one half (4 ½) feet
above the crown root, or, two (2) or more trunks measuring three (3) inches each or greater in diameter,
measured at a point four and one half (4 ½) feet above the crown root.
• Any other living oak tree with a trunk diameter larger than twelve (12) inches measured at a point four
and one half (4 ½) feet above the crown root, or, two (2) or more trunks measuring ten (10) inches each
or greater in diameter measured at a point four and one half (4 ½) feet above the crown root.
On March 3, 2015, the City Council adopted Ordinance No. 2323 amending the code to add Sycamore trees to the
list of City's Tree Preservation Regulations. The protected trees are Oak and Sycamore trees. Protected Sycamore
trees are defined as:
• Plantanus racemosa (Sycamore) with a trunk diameter larger than six (6) inches measured at a point four
and one-half (4½) feet above the root crown, or two (2) or more trunks measuring four (4) inches each or
greater in diameter, measured at a point four and one-half (4½) feet above the root crown.
On August 2, 2016, The City Council adopted Ordinance No. 2338 to add additional protected trees and unprotected
trees to the City’s tree preservation regulations. In September, the City began protecting mature trees that are located
within a required front, side, street-side, or rear yard setback area that are either larger than 12 inches in diameter or
two or more trunks larger than 10 inches in diameter if there are multiple trunks.
Below is a list of the unprotected trees:
1. Fruit trees
2. Fraxinus uhdei (Shamel Ash)
3. Ficuses – Exception: Ficus macrophylla (Moreton Bay Fig)
4. Eucalyptus
5. Ailanthus altissima (Tree of Heaven)
6. Arecaceae (Palm Tree)
7. Schinus terebinthifolius (Brazilian Pepper)
8. Ceratonia siliqua (Carob)
9. Betula pendula (European White Birch)
10. Grevillea robusta (Silk Oak)
11. Morus (Mulberry)
12. Acer saccharinum (Silver Maple)
13. Cupressus sempervirens (Italian cypress)
14. Populus Fremontii (Western Cottonwood)
15. Alnus rhombifolia (White Alder)
16. Populus trichocarpa (Black Cottonwood)
17. Populus ‘Highland’ hybrid
18. Salix lasiolepis (Arroyo Willow)
19. Liquidambars (Sweet Gum)
Protected Tree Report: Survey, Encroachment and Protection Plan 603 W. Camino Real Ave., Arcadia, 91007 Michael Crane, RCA #440. February 2019 4 TREE SURVEY This table lists all oaks and sycamore trees with trunk diameters measuring four inches or greater located on or near the property, as well as all other trees with trunk diameters measuring six inches or greater located on or encroaching onto the property. Off-site trees are indicated with an “os” next to their tree numbers. Multi-trunked specimens are indicated next to the trunk diameter with an “m” and the diameters of the two largest trunks are listed. A determination is then provided for the protected status of each tree based on criteria of species, size and location. All street trees or trees in public areas are Protected regardless of species or size and these trees are marked with an asterisk in the Location column. Tree numbers correspond to the tree locations plotted on the site plan included in this report and to all references to each tree in this report. Only Protected Trees have numbered tags affixed to their trunks. Tree Survey for 603 W. Camino Real Ave., Arcadia Tree Identification Protected Status Tree # Botanical Name Common Name Trunk Diameter Protected Species Minimum Required Size Located in Protected Area PROTECTED TREE 1 Cedrus deodara Deodar Cedar 36" Yes Yes Yes Yes 2 Cedrus deodara Deodar Cedar 28” Yes Yes Yes Yes 3 Quercus agrifolia Coast Live Oak 6" Yes Yes Yes Yes 4os Ceratonia siliqua Carob 34” Yes Yes Yes Yes 5 Fraxinus uhedi Shamel Ash 30” No Yes Yes No 6 Eucalyptus sp. Eucalyptus 18” No Yes No No 7 Ficus carrica Edible Fig m 6”,6” No No No No 8 Citrus sp. Citrus m 3”,3” No No Yes No
Protected Tree Report: Survey, Encroachment and Protection Plan 603 W. Camino Real Ave., Arcadia, 91007 Michael Crane, RCA #440. February 2019 5 This chart includes all Protected Trees that are either located or encroaching on the property. It provides physical data collected from field observations. The trees have been surveyed and numbers correspond to the Site Plan included in this report. Tree numbers with an “os” indicate that the specimen is located off-site and a portion of the canopy extends over the subject property. Trunk diameters of multi-trunked specimens are listed by the size of the largest trunk or leader with the cumulative of all trunks listed in parentheses. TREE CHARACTERISTICS & HEALTH MATRIX CHARACTERISTICS HEALTH SIZE FORM CROWN CLASS AGE CLASS FOLIAGE DENSITY SHOOT GROWTH WOUND DEFENSE VIGOR CLASS TREE NUMBER SPECIES TRUNK DIAMETER
(INCHES)
APPROXIMATE HEIGHT
(FEET)
AVERAGE SPREAD
(FEET)
SYMMETRIC
ASYMMETRIC
DOMINANT
CO-DOMINANT
SUPPRESED
YOUNG
MATURE
OVERMATURE
NORMAL
SPARSE
DISEASE / INSECT
AVERAGE
POOR
TWIG DIEBACK
NORMAL
POOR
WOOD DECAY
GOOD
POOR
DISEASED/HAZARDOUS 1 Cedrus deodara 36 60 45 X X X X X X X 2 Cedrus deodara 28 45 35 X X X X X X X X X X 3 Quercus agrifolia 6 15 15 X X X X X X X 4os Ceratonia siliqua 34 25 45 X X X X X X X X
Protected Tree Report: Survey, Encroachment and Protection Plan 603 W. Camino Real Ave., Arcadia, 91007 Michael Crane, RCA #440. February 2019 6 This chart includes all Protected Trees that are located on the property and any off-site Protected Native Trees (oaks and sycamores) encroaching on the property. It provides data collected from the analysis of construction plans. The tree has been surveyed and numbers correspond to the Site Plan included in this report. Tree numbers with an “os” indicate that the specimen is located off-site and a portion of the canopy extends over the subject property. For rootzone impacts, the required excavation is considered only for unbuffered areas. Areas that excavation will occur where existing similar infrastructure exists, e.g. overexcavation and compaction in the footprint of existing home foundation, grading for driveway in the footprint of existing driveway, are considered non-encroachments. CONSTRUCTION IMPACTS MATRIX TREE SPECIES SIZE & CONDITION ROOTZONE IMPACTS REQUIRED PRUNING OF LIVE CROWN TREE NUMBER Protected Trees: • Quercus agrifolia, engelmannii, and any other species of Quercus genus larger than 12” • Platanus racemosa • Any tree located in the public right-of-way • All other species 12” or larger that are not on the exemption list TRUNK DIAMETER (DBH)
CONDITION
Sides of tree where excavation
(six inches or deeper) will occur
Sides where excavation impacts are
buffered by existing infrastructure
Excavation will remain a distance
of at least 10 X DBH from trunk
Excavation will remain a distance
of at least 5 X DBH from trunk
Excavation will remain a distance
of at least 3 X DBH from the trunk
Removal or Relocation
Additional light grading less than
6" deep to occur within dripline
Estimated % of total root mass
to be removed or severed
No Pruning Required
Pruning not to exceed 10%
Pruning not to exceed 30%
Number of cuts larger than 3"
in diameter required
Diameter of cuts for branch removals 1 Cedrus deodara 36 Good N,W W - - - - - - - 2 Cedrus deodara 28 Poor W W - - - - - - - 3 Quercus agrifolia 6 Fair N,S - - - - - - - - 4os Ceratonia siliqua 34 Fair - - Yes <20 0 N/A
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
7
DESIGN ANALYSIS OF PROTECTED TREE ENCROACHMENTS
Refer to Site Plan located in pocket at back of this report, and Photos in Appendix
A, page 9.
Analysis regarding rootzone impacts are based on the type of impact, e.g, soil
compaction, grading, and excavation; as well as the distance from the trunk that the
impacts will occur. It is commonly accepted among professional arborists that a distance
equal to three times a trunks diameter contains the structural roots responsible for
keeping the tree upright. This critical rootzone area is defined as the root plate. Beyond
the root plate the roots typically taper off into smaller, less significant sizes. These
smaller roots are usually two inches in diameter or smaller and make up the rootmass
responsible for water and nutrient uptake. Although roots of these sizes can be cut
without significantly impacting health and stability it is advised that no more than 30
percent of the rootmass within the dripline is severed. The bulk of the rootmass is
located within the top three feet of soil and root growth slows or halts when soil bulk
density exceeds 1.60 g/cm3 for most soils. More information regarding rootzone impacts
is provided in the Excavation and Root Pruning section of the Construction Impact
Guidelines, Appendix D.
Tree #1 – 36” Deodar cedar: Located in the side corner yard along Lovell Ave. The
foundation of the new home will be built 20 feet from the trunk on its west side.
Overexcavation will come as close as 15 feet but will occur within the footprint of the
existing home. The new driveway will come as close as 14 feet from the trunk on its
north side. The entire exposed rootzone area is covered with Asparagus Fern (Asparagus
setaceus). This tough and invasive plant is deeply rooted, resistant to many herbicides
and extremely pervasive. It is extremely difficult to eradicate without deep cultivation,
which Deodar Cedars are rather intolerant of. It is likely that the tree will be significantly
impacted with any serious attempt at removing the invasive undergrowth plant. The tree
is proposed to be removed and replaced under a Healthy Tree Removal Permit.
Tree #2 – 28” Deodar cedar: Located in the side corner yard near Tree #1. This tree is
diseased/hazardous. It has been topped, presumably to mitigate for a trunk failure. The
branches below the heading cut are cracked and in decline, and approximately one third
of the branches in the crown are in decline with the foliage browning. New shoot growth
is very poor or non-existent throughout the crown. The tree is proposed to be removed
and replaced under a Diseased/Hazardous Tree Removal Permit.
Tree #3 – 6” Coast Live Oak: Located in the back yard. The trunk straddles the west
property line. A concrete block wall is planned to be built on the property line. By virtue
of its location the tree is assumed to be a volunteer. It is young and has never been
structurally pruned; and instead of being accommodated into the wall’s design it is
proposed to be removed and replaced under a Healthy Tree Removal Permit.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
8
Tree #4 – 34” Carob: Located in the public right-of-way setback area of the property to the
north. It is a street tree along Lovell Ave. The new driveway will be built on the south side of
the property and the cut for the driveway entry apron will come as close as seven feet from the
trunk. The grade cut will be slightly less than six inches deep. The existing concrete block
wall on the north property line, which is located under the tree, will remain. Some modest
landscape renovation work will encroach.
FINDINGS
• Tree #1 is in Fair condition, but will be significantly impacted by the likely removal of the
understory Asparagus Fern; and to a lesser degree the encroachment of the new driveway. It
is proposed for removal . under a Healthy Tree Removal Permit.
• Tree #2 is in decline and is a diseased/hazardous tree. It is proposed for removal under a
Diseased/Hazardous Tree Removal Permit..
• Tree #3 is a young volunteer Oak that is poorly located for the construction of a typical
straight property line fence. It is proposed for removal under a Healthy Tree Removal
Permit..
• Impacts on Tree #4 for the relatively shallow grade cut required for the new driveway can be
reliably managed and minimized by the consultant through monitoring of the excavation.
• The primary haul route for the duration of the project will be the existing driveway that is on
the west side of the property and well clear of Tree #4.
MITIGATION
Trees #1, #2 and #3 can be mitigated at 2:1 with trees planted in the public right-of way setback
areas along W. Camino Real Ave. and Lovell Ave. There are currently no street trees on the
property. The dominant Street Tree species in the immediate vicinity is Crape Myrtle
(Lagerstromia indica).
The mitigation tree shall be of a size no smaller than a 36” box. The tree shall be a nursery
grown specimen of good quality, and installed at any time during the project, with the
establishment of a proper protection zone and supplied irrigation.
The city shall determine the actual mitigation under the conditions of a tree removal permit for
Trees #1, #2 and #3.
RECOMMENDATIONS
• The locations for the protective fencing recommended near Tree #4 is drawn with a
dashed line on the Site Plan included in this report.
• Mitigation trees should be planted near the end of the project during the landscape installation
phase.
• Refer to Tree Planting Specificatiions in Appendix B for complete instructions on planting
container-grown trees.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
9
APPENDIX A – Photos
ABOVE: Looking north at the property from the corner of W. Camino Real
and Lovell Ave. The two Protected Cedar Trees (Trees #1 and #2) are at the
east side. Both trees will be removed and replaced. BELOW: Looking
northwest at Trees #1 and #2. Tree #2 is in decline.
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2
2
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Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
10
ABOVE: Close up of the top of Tree #2. It had been headed and a couple
branches below the heading cut are broken and in decline. BELOW: The thick
and wide stand of Asparagus Fern will be a massive challenge to eliminate. An
adequate effort will require rototilling, which will significantly impact the Cedars.
2
2
1
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
11
ABOVE: Looking north at Tree #3. Its trunk straddles the west property line. A
block wall is planned to be built on the property line. BELOW: Looking west.
The young tree is most likely a volunteer. It has poor structure and is not a good
candidate for preservation. It is proposed for removal and replacement.
3
3
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
12
ABOVE: Looking west at Tree #4 from Lovell Ave. The new driveway
will be built as close as seven feet from the trunk on its south (left) side.
The existing block wall that defines the two properties will remain.
4
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
13
APPENDIX B – Tree Planting
Taken from: Best Management Practices ANSI A300 Part 6: Tree, Shrub, and Other
Woody Plant Maintenance – Standard Practices (Transplanting)
Container Trees
Root systems of container-grown trees must be developed well enough to hold the potting
substrate together, but they must not be circling or matting against the inside of the
container. Roots that circled in a smaller container may be hidden inside the root ball.
Problems associated with uncorrected circling roots of container-grown stock may not be
exhibited for years. Teasing apart or cutting into a section of the root ball to look for
them may be advisable, unless you have confidence in your supplier.
The point where the first structural roots emerge from the trunk should be near the soil
surface. Containerized and container-grown trees are sometimes planted too deeply.
This situation should be corrected at planning, or the plants should be rejected.
Trees should be lifted by the container whenever possible. In some areas it is accepted
practice to lift larger trees (more than 3 inches caliper) by the stem. Thin barked trees
especially require extensive padding when lifting by the trunk.
Because container substrate typically is well-drained and frequently irrigated in the
nursery to avoid drought stress, container-grown trees will require frequent watering after
leaving the nursery. Trees may dry out quickly during transport. When stored at the
planting site for any time, they require irrigation once or twice daily. If the root ball of a
container plant dries out, the soil may become water repellant. If this occurs, be sure the
root ball is thoroughly rewetted before planting. Addition of a surfactant may be
necessary to re-wet the substrate thoroughly.
Preparing the Planting Hole
The planting hole should be of sufficient size for rapid initial root development during the
first year. The planting hole shape should not restrict root spread beyond the planting
hole. Ideally, these objectives should be achieved with a minimum of cost and effort.
Size and Shape
On sites with high-quality soil, the planting hole needs to be wide enough to facilitate
planting, but the soil should not be disturbed under the root ball – or the ball might sink
afterward. On sites with poor-quality soil (compacted, clayey, or poorly drained), trees
benefit from larger planting holes. A larger hole, or loosened, cultivated surrounding
soil, means a greater volume of friable soil for rapid initial root growth. For container-
grown trees, the planting hole should be slightly shallower than the root ball. In many
poor-quality urban soils, root growth from the bottom half of the root ball will be
minimal due to inadequate drainage and aeration. If the structural roots are more than a
few inches below the root ball surface, the planting hole depth will have to be adjusted, or
the tree may have to be rejected.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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Digging a wide hole with sloped or stepped sides used the majority of the digging effort
to excavate surface soils where the roots will grow most vigorously. If the roots are
unable to grow into the compacted subsoil, a hole with sloped sides will allow them to
gradually grow back up toward the better quality surface soils and continue to spread
beyond the planting hole. A planting hole that is at least two times the width of the root
ball diameter is required for sites with poor soils. A wide hole for the full depth of the
root ball may not provide any more usable root space if the soil at the bottom is saturated
at times.
A hole with vertical sides can take more effort today. Species with very aggressive root
growth, such as Siberian elm (Ulmus pumila) and poplar (Populus spp.), may be able to
establish on poor quality sites without the planting hole being enlarged. Remember, the
same characteristics that help these species grow well under difficult conditions also
make them the species most likely to have root conflicts with infrastructure, especially if
planted too close to pavement and structures.
When preparing the wide planting hole, it may not be necessary to actually remove all the
soil from the hole and then put it back again. It may be more efficient to first dig a
planting hole at least half again as wide as the root ball. Then, after the tree has been set,
but before the hole is backfilled, use a spade to slope the edges to about half the depth
and allow the soil to fall in the hole.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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Glazing and Drying
Mechanical digging sometimes results in glazing the soil of the planting hole wall. Clay
soils will glaze most readily. Roots may have difficulty growing through the glazed
surface. It is best to eliminate the potential for trouble by using a hand tool to break up
glazed surfaces before planting.
If holes are dug in advance and left exposed, the soil may become very hard and dry on
the sides of the hole. Break up the dry surface to expose moist soil before planting.
Drainage
Poor drainage accounts for high losses of new trees. When soil permeability is slow, the
soil in the planning hole can remain saturated for long periods. Even short periods of
saturation can kill roots of many species. Irrigation systems designed to provide large
amounts of water to lawn often overirrigate trees. Excess water can easily accumulate in
planting holes, even during severe droughts, saturating the soil and driving out oxygen
needed by the roots.
Solving drainage problems may be expensive, but doing so is essential for acceptable tree
performance. A simple test can be conducted before planting to identify potential
problem areas. Auger a 4-inch-diameter hole as deep as the expected root ball. Put a
handful of gravel in the bottom and fill the hole with water to presaturate the soil. For
one hour, refill as needed to maintain the water level, then stop adding water. After 24
hours, fill with water to 12 inches from the bottom and measure the rate of fall of the
water surface. A drainage rate of less than ¼ inch per hour is cause for concern and
indicates that drainage from the planting hole may be needed.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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On many sites, improving the drainage on the entire side may be a better approach.
Selecting species more tolerant of poor drainage is another option when drainage cannot
be improved.
Drainage for individual trees can be improved in several ways. Occasionally, a well-
drained layer of soil exists underneath a poorly drained layer and filled with gravel or
coarse sand to provide a path for the water to flow down to the well-drained layer.
Perforated plastic pipe or products manufactured specifically to create drainage channels
can be used to discharge water from the bottom of the planting hole to a lower level. A
3-inch fall per 100 feet of pipe is the minimal slope toobtain adequate water flow. This
approach works well for trees planted on slopes. If the ground is level, permission
sometimes can be obtained to connect the pipe into a nearby storm sewer. If the water
cannot be drained away to a lower area or a deeper soil layer, the site may not be suitable
for planting many tree species.
A layer of gravel in the bottom of the planting hole will not improve drainage and can, in
fact, make drainage worse. Water accumulates in the finer-textured soil above this layer
of course gravel until the soil is completely saturated. This situation is known as a
perched water table.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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Planting high, with the top of the root ball above the surrounding grade, is sometimes
recommended for poorly drained sites. If trees are planted high, no more than one-fourth
to one-third of the root ball should be above grade, and the soil should be sloped
gradually (1:10) between the top of the root ball and the original grade. This method may
use excess soil from the planting hole or even require additional soil. In extreme cases,
berms may have to be created in order to plant trees even higher. An important drawback
of raising trees up is that the soil in the upper part of the root ball and the backfill may
dry out quickly during dry periods. An application of an inch or two of mulch would be
very desirable.
Planting
Proper Planting Depth
In most cases, the top of the root ball at planting should be an inch or two higher than the
surrounding grade to correct for expected settling of backfill soil and flattening of the
root ball. Before placing the heavy root ball in the hole, be sure that the depth of each
hole is the same as, or slightly less than, the distance between the topmost structural roots
and the bottom of the root ball. Planting with the roots too deep is very difficult to
correct when discovered several months or a years later. Structural root depth should be
checked, and rechecked, starting with selecting trees from the nursery and one final time
just before backfilling the planting hole. If the structural roots are deeper than 3 inches
below the top surface of the root ball when measured 4 inches from the trunk, the
planting hole should be shallower to account for it. Ideally, evidence of the structural
roots will be visible just at the point where they emerge from the trunk. However, on
some species and on very young trees, no root flare may have been formed yet.
If there is extra soil over the structural roots, it is probably best to leave the root ball
intact until it is placed in the planting hole rather than to unwrap it and strip the soil off
the top before placing the ball in the hole.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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A300 Part 6: Tree, Shrub, and Other Woody Plant Maintenance – Standard Practices
(Transplanting) (2005) uses the following wording to address planting depth: “The
bottom of the trunk flare shall be at or above the finished grade.”
It is clear that both the A300 standard and ISA’s Best Management Practices set forth to
address the importance of not planting too deeply. However, ISA seeks to avoid any
confusion concerning the location of the bottom of the trunk flare.
Many young trees lack a well-defined trunk flare, and structural roots may emerge from
the vertical trunk/ root tissue over a significant distance. Attempting to place the bottom
of the trunk flare of a young tree above grade increases the danger of exposing too much
of the root system. ISA has endeavored to describe how to determine the depth of the
structural roots, even when no trunk flare is visible, and how to guard against planting
too deeply.
.
Structural Root Depth
Depth of roots at planting time is critical. Do not assume roots are near the top of the
container root ball.
Probe the root ball for structural roots with a surveyors chaining pin or similar tool to
check for structural route depth. Generally, upper-most structural roots should be within
1 to 3 inches of the soil surface, measured 4 inches from the trunk, but there may be
exceptions, such as steeply angled roots. Ideally, the structural roots will be visible just
at the point where they emerge from the trunk. However, on some species and on very
young trees, no root flare may have been formed yet.
According to the American Standard for Nursery Stock (ANSI Z60.1-2004), “Soil above
the root flare shall not be included in the root ball depth measurement.” If the resulting
depth measurement of the root ball does not meet the minimum, the tree should be
rejected.
Plant the root ball so that the uppermost structural roots are 1 o 3 inches below
surrounding grade when measured 4 inches from the trunk.
When soil is removed from the base of the trunk, the newly exposed tissue may be more
susceptible to cold and sunscald damage. Exercise caution until more is known.
Mulch should be no more than 2 inches deep over the root ball.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
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Of course, it will be necessary to determine the root depth in the ball so that the hole can
be dug to the appropriate depth. Although planting too deeply is a serious problem,
exposure of the roots is not desirable, either.
At this point, a decision must be make whether to strip off the excess soil or to leave it to
erode. If there are few or no roots in the excess soil, stripping it to the appropriate depth
may be the best alternative. However, the extra soil over the structural roots could also
be filled with fibrous roots, which, if removed suddenly, could cause extra stress.
In some situations, it may be preferable to leave the extra soil remaining above grade. If
the soil is left in place, it should erode over time as the root system becomes established
in the new site. Some experience has shown that suddenly removing extra soil from the
base of the trunk and exposing the roots may lead to damage from cold temperatures or
sunscald in certain climates. There also may be consequences to leaving soil in contact
with the trunk. Certain disease problems have been associated with prolonged moisture
on the trunks of trees that were planted too deeply, and the incidence of girdling root
formation may be correlated with planting depth. More research is needed on search of
these issues.
Disrupting Circling and Matted Roots
Though many techniques have been developed to reduce root circling in containers, the
problem is still frequently encountered in the landscape. Circling roots should be
loosened and spread out – or cut if necessary. Excessive cutting of the roots can lead to
serious root loss and could lead to increased stress after planting, but moderate stress is
preferable to allowing circling roots to persist. Be aware that additional circling roots
also may be present deep within the root ball if the
tree was grown in smaller pots during earlier stages of production.
Soil Amendments
On sites with high-quality soil, the backfill does not require amending. Consider
amendments only on sites with poor-quality soil to improve soil structure, water-holding
capacity, or drainage. Amending the whole planting site is preferred.
Amending only the backfill soil used in the planting hole may provide limited benefit but
will not cause harm if done properly. Discontinuity of soil properties between amended
backfill and site soil has been blamed for inhabiting root growth out of the planting hole.
In reality, the roots simply are unable to penetrate the poor quality of site soil outside of
the planting hole. It appears the soil transition, rather than the impenetrable clay soil, is
responsible.
If a simple amendment is desired, dig a large hole and mix the soil from the hole with
composted organic matter (5 percent by weight, 20 to 35 percent by volume, depending
on the material). Test the pH of the compost, especially if planting acid-loving species.
Enlist the assistance of a qualified soil scientist before attempting more extensive soil
modification, especially if a large-scale planting is involved.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
20
Backfilling
When refilling the plating hole, the backfill soil should be free of clumps. While holding
the bare-root tree in the correct position, shake the tree while adding loose soil around the
roots to allow the soil to settle in between the roots. Periodically tamp the soil lightly
until no air pockets remain, without causing the tree to settle deeper in the hole. Add
water to settle the soil around the roots, and then add more soil if necessary. Check again
to be sure that the structural roots are just below the soil surface.
Firmly tamp the backfill soil around the base of the root ball. The rest of the soil should
be tamped only lightly or left to settle on its own. Watering will assist in settling the soil
naturally. Excessive tamping can compact soil and slow water penetration and root
growth. The soil can be mounded slightly between the root ball and the edge of the
planting hole to allow for settling, but do not cover the root ball with soil. If water is
expected to percolate slowly into the soil, or if the planting site is not level, a raised ring
of soil can be formed around the edge of the root ball to create a shallow basin that can be
filled with water.
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
21
AUTHOR’S CREDENTIALS
Protected Tree Report: Survey, Encroachment and Protection Plan
603 W. Camino Real Ave., Arcadia, 91007
Michael Crane, RCA #440. February 2019
22
CERTIFICATION OF PERFORMANCE
I, Michael Crane, certify that:
• I have personally inspected the tree(s) and the property referred to in this report and have
stated my findings accurately.
• I have no current or prospective interest in the vegetation or the property that is the
subject of this report and have no personal interest or bias with respect to the parties
involved.
• The analysis, opinions, and conclusions stated herein are my own and are based on
current scientific procedures and facts.
• My analysis, opinions, and conclusions were developed and this report has been prepared
according to commonly accepted arboricultural practices.
• No one provided significant professional assistance to me, except as indicated within the
report.
• My compensation is not contingent upon the reporting of a predetermined conclusion that
favors the cause of the client or any other party not upon the results of the assessment, the
attainment of stipulated results, or the occurrence of any subsequent events.
I further certify that I am a member in good standing of the American Society of
Consulting Arborists and the International Society of Arboriculture. I have been
involved in the field of Horticulture in a full-time capacity for a period of more than 25
years.
Signed: ____________________________
Registered Consulting Arborist #440; American Society of Consulting Arborist
Board Certified Master Arborist #WE 6643B; International Society of Arboriculture
Licensed California Agricultural Pest Control Adviser #AA08269
February 2, 2019
Date: ______________________________