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HomeMy WebLinkAbout13 ADOPT URBAN FOREST MGMNT PLAN 11-17-09,~. Agenda Item 13 ~ Reviewed: AGENDA REPORT City Manager Finance Director NIA MEETING DATE: NOVEMBER 17, 2009 TO: WILLIAM A. HUSTON, CITY MANAGER FROM: DOUGLAS S. STACK, ACTING DIRECTOR OF PUBLIC WORKS/CITY ENGINEER SUBJECT: ADOPTION OF AN URBAN FOREST MANAGEMENT PLAN SUMMARY The City of Tustin is presently designated a "Tree City USA" City. Adoption of the proposed Urban Forest Management Plan will establish guidelines for the management of City trees, and allow the City to be recertified as a Tree City USA City and apply for the Tree City USA "Growth Award" designation. RECOMMENDATION It is recommended that the City Council adopt the City of Tustin Urban Forest Management Plan. FISCAL IMPACT There is no fiscal impact associated with this action. BACKGROUND Trees are an important component of Tustin's community environment that enhance the appearance of the City's streets and parks, moderate noise levels and cleanse pollutants such as carbon dioxide from the air. Properly managed trees return overall benefits and value to the community far in excess of the time and money invested for their care and maintenance. The Public Works Department maintains a community forest of over 15,000 trees and has been designated a "Tree City USA" City by the National Arbor Day Foundation since 1996. The proposed Urban Forest Management Plan (Plan) includes goals, standards and practices for the species selection, planting, maintenance and removal of City trees. The Plan also includes the City's Arboricultural and Landscape Standards and Specifications (ALBS) and designates the Public Works Director to be responsible for the enforcement of the ALBS and the issuance of permits for the planting, maintenance and removal of trees in the public right- of-way, parks and other City properties. Permits are issued without cost and proposed work must comply with established standards as determined by the Director. Adoption of an Urban Forest Management Plan November 17, 2009 Page 2 Adoption of the Urban Forest Management Plan will allow the City to meet the standards for recertification as a "Tree City USA" and to apply for the Tree City USA Growth Award. The Growth Award is given as special recognition for the planning, management and implementation of improved maintenance strategies. Copies of the Urban Forest Management Plan are available for review at the City Clerk's and Field Services offices. S. Stack rector of Public Works/City Engineer Attachment: Urban Forestry Management Plan ~~/ J on hurchill ` Field Services Manager Adoption of an Urban Forest Management Plan.docx URBAN FOREST MANAGEMENT PLAN November 2009 TABLE OF CONTENTS Section Title Page Number Introduction ...........................................................................1 II Goals ....................................................................................2 III Urban Forest Management Guidelines .................................4 A. Tree Inventories and Maintenance Records ..............4 B. Tree Planting ..............................................................4 C. Tree Pruning ..............................................................6 D. Preservation and Infrastructure Consideration.........10 E. Tree Removal and Replacement ..............................13 F. Tree Selection Lists and Planting Criteria ................14 IV Closing Statement ..............................................................16 INTRODUCTION The City of Tustin is amulti-cultural community of homes and businesses nestled in scenic Orange County. The City of Tustin is rooted in the past from the captivating historic homes to the shops of Old Town. Within the rights-of way, which are owned and maintained by our community, exists an urban forest that has a diverse mixture of trees. From the gloriously old, historical trees to an abundant variety of younger trees, our urban forest allows the City to both preserve its heritage and at the same time reach out for the future. This urban forest makes a tremendous contribution to the character and ambiance of the City, and as a result of its historical significance, abundant variety, and the way it enhances the visual aesthetics of the community, it is considered a valuable asset. The Urban Forest Management Plan is a guide for the care and maintenance of the City's urban forest and is designed in a manner to promote the health and welfare of the trees in acost-effective manner. The Urban Forest Management Plan sets forth guidelines for the care and maintenance of Tustin's urban forest throughout the entire life cycle of any given tree. These guidelines include the selection, planting, pruning, preservation, and removal of trees throughout the community. These standards are in compliance with the standards set forth for tree care by the International Society of Arboriculture. The City of Tustin is committed to the preservation of trees, while at the same time providing for safe and functional parks, sidewalks, curbs, gutters, and other infrastructure features. Although this policy may have some short term financial impacts, the long-term results improve and enhance the image of the City of Tustin. Section I Goals 1) Minimize City Liability Reduce City liability through proper and selective pruning. Select varieties of trees which are compatible with and best suited to their individual sites. 2) Establish and Maintain Maximum Tree Coverage Require 1 tree per 40 feet of residential street frontage with a minimum of one tree per lot. Apply the same requirements to commercial frontage, subject to exceptions made on a situation-by- situation basis. 3) Maintain Trees in a Healthy Condition Through Recognized Horticulturally Correct Practices Adhere to the pruning standards developed by the International Society of Arboriculture, which have been endorsed by the State of California via Assembly Bill 3749 (Tree Pruning). 4) Establish and Maintain a Diversified Urban Forest at Various Stages of Maturity Increase the diversity of the urban forest by adding new species. Give special emphasis to incorporating trees in various stages of development 5) Promote Conservation of Tree Resources Promote apro-tree environment with an emphasis on tree preservation. 6) Select Trees A.apropriiate to Planting Sites Make selections with the emphasis on minimizing hazards, nuisances, landscape damage, and maintenance costs. 7) Central Tree Management Under a Certified Arborist The tree management program will conform to the standards of the International Society of Arboriculture (ISA). 8) Promote Efficient and Cost Effective Management Provide the most cost efficient service possible, developing work schedules for the planting, maintenance and removal of trees based on a City-wide tree survey. 2 9) Community Education Educate the community regarding the importance of a good Urban Forest Management Plan. a) Distribute information on urban forest related issues b) Solicit and encourage community awareness c) Involve the public in species selection for tree replacement programs (15-year transition plans) d) Encourage public-assisted tree planting projects (i.e., Arbor Day Celebrations, Donate-a- Tree, etc. ) 10) External Funding for Urban Forests Identify and pursue external funding sources for support of the urban forest such as tree replacement funding through corporate donations and State/Federal grants. 3 Section II Urban Forest Management Plan Guidelines The City of Tustin has developed a set of guidelines that will facilitate the implementation of the various goals identified in the Urban Forest Management Plan. These guidelines address the following areas: A. Tree Inventories and Maintenance Records B. Tree Planting C. Tree Pruning D. Preservation and Infrastructure Considerations E. Tree Removal and Replacement F. Tree Selection and Planting Criteria A. Tree Inventories and Maintenance Records Inventory trees and maintain computerized records on the maintenance of each individual site entry. These maintenance records will provide a basis for the development of maintenance schedules and planting lists. The maintenance schedules shall contain the following information: 1. Address, street, block number 2. Sequential order of trees (numbered left to right beginning at the section facing front door; trees located on a side street shall also be numbered from left to right) 3. Species, height, trunk diameter, condition 4. Date of inspection 5. Maintenance history B. Tree Planting These guidelines shall be followed when planting a tree: When planting in a parkway, center the tree between the curb and sidewalk. 2. When planting in an area without a sidewalk, plant tree 4' to 6' from existing or planned curb or street. 3. Plant a tree a minimum of 10' from driveways, water meters and mainlines, sewer lines, traffic and directional signs, and fire hydrants; 15 from street lights; 5' from other utilities; and 30' 4 from street corners. 4. The hole in which the tree is to be planted must be dug to twice the diameter of the root ball and to the depth of the root ball. The outer edge of the hole should flare downward, away from the root ball to allow water to flow away from the root ball, and not collect in the root zone. 5. When Bare-Root Planting, the diameter of the hole must be twice the width of the root spread. 6. Remove all rocks and debris larger than 2" in diameter from backfill soil. 7. Removal any dead or diseased roots and/or branches before planting trees. 8. Slightly loosen or score root ball before placing tree into planting hole. 9. For bare-root trees, using backfill material, form a cone of soil within the planting hole, and spread roots over the cone. 10. Add Agriform fertilizer tablets to the planting hole prior to backfilling. with analysis 20-18-15 at a recommended amount of: 4 tablets for bare-root and 15-gallon containers and 8 tablets for 24" box trees. 11. When backfilling, soil level must reach original soil line for containerized trees and it must reach the line of color differentiation on bare-root trees. 12. Tamp soil after backfilling to proper height. 13. Apply water to soil to allow setting. 14. If necessary, add more backfill soil and tamp, keeping tree at specified height. 15. Create a water basin of firmly packed soil (24" in diameter) at the base of each tree. 16. Double stake alt trees unable to stand alone using a 2-inch diameter, 10-foot high lodge pole stake placed on the windward side of the tree. 17. Stakes shall be sunk into soil to a depth of approximately 2'. 18. Place stakes 8" to 12" from the tree trunk at the base. 19. Secure 2 tree ties per stake ("Tie It" as supplied by Bishop Company or equal) at heights equal to 1/2 to 2/3 of the total tree height. Tie loosely to allow for tree movement. 20. Install arbor guards or "tree shoes" around the base of each tree. 21. Water all trees thoroughly upon the completion of planting. 22. Plant trees a minimum of 3/4" to 1"above grade to allow for settling in the planting holes. 5 C. Tree Pruninsl 1. Pruning Techniques a) Type of Pruning Cuts Thinning Cut - A thinning cut removes a branch at its point of attachment or shortens it to a lateral large enough (at least 1/2 the diameter of the cut being made to assume the terminal role (this latter cut is known as drop crotching). Thinning cuts can effectively direct growth and retain the natural form of the tree. ii. Heading Cut - A heading cut removes a branch to a stub, a bud, or a lateral branch not large enough to assume the terminal role. A heading cut is not a correct practice and should never be used. b) General Considerations i. Pruning Cuts -Pruning cuts should be clean and smooth, with the bark at the edge of the cut firmly attached to the wood. ii. Large or heavy branches which cannot be thrown clear should be lowered on ropes to prevent injury to the tree and other property. iii. Wound dressings and tree paints have not been shown to be effective in preventing or reducing decay and are not recommended for preventing decay. However, asphalt tree paint can minimize borer attacks on fresh pruning wounds of several species, i.e., Elm, Pecan, and Oak. Fungicidal paints are effective for certain canker-causing disease organisms. If asphalt wound dressing is used for cosmetic purposes or to discourage borer attacks, it should be applied in a thin coat at the time of pruning. 2. Location of Pruning Cuts a) When removing a live branch, make the pruning cut either just outside the branch bark ridge and collar, or just outside the branch bark ridge and through the outside half of the collar. If no collar is visible, as in Birch and Alder, the angle of the cut should approximate the angle formed by the branch bark ridge and the axis of the trunk or the branch being cut. b) When removing a dead branch, the final cut should be made outside the collar of live callus tissue, even if the collar has grown out along the dead branch. c) To prevent tearing or stripping of the bark when removing a large branch, remove most of the branch making two cuts, the first one from the bottom, and the second one from above, close to the first cut. d) When reducing the length of a branch or the height of a leader, the final cut should be made just outside the branch bark ridge of the branch to be cut. To minimize the possibility of the branch splitting out, the cut should approximately bisect the angle formed by the branch bark ridge and an imaginary line perpendicular to the trunk or the branch cut. 6 3. Structural Considerations a) A goal of structural pruning is required tb maintain the size of lateral branches to less than 3/4 the diameter of the truck or parent branch. If the branch is co-dominate or close to the size of the trunk or the parent branch, thin the laterals on the competing branch 15 to 25 percent, particularly near the terminal. Thin the parent branch less, if at all, in order to keep it dominant. b) On large trees, branches that are more than 1/3 the diameter of the trunk should be spaced at least 24" apart, on center. If this is not possible because of the present size of the tree, such branches should have 15 to 25 percent of their foliage thinned, particularly near the terminals. c) Before beginning work in a tree, inspect the root collar of the tree for signs of weak or broken roots; the presence of decay or cavities; for adventitious roots; or signs of any other adverse conditions. If the tree appears to be hazardous, it may be wise to remove it, or at least obtain a second opinion. 4. Prunina Severity a) The removal of many small branches rather than a few large branches requires more time but will produce a more natural appearance; force fewer water sprouts; and lengthen the vigor and structure of mature trees. b) On mature trees the maximum size (base diameter) of any `occasional' undesirable branch that may be left within a tree crown, such as 1/2", 1" or 2" branch diameter, establishes the detail or degree of pruning desired and should be specified before work begins. c) No more than 1/3 of the live foliage of a tree should be removed at one time without good reason. 5. Climbing Techniques a) Climbing and pruning practices should not injure the tree, except for the pruning cuts. b) The use of climbing spurs or gaffs should be avoided. Their use may be considered only when branches are more than throw-line distance apart. In such cases, the spurs should be removed as soon as the climber is tied in. Spurs may be used to reach an injured climber or when removing a tree. c) Rope injury to thin-barked trees from loading out heaving limbs should be avoided by installing a block in the tree to cant' the load. This technique may also be used to reduce injury to a branch crotch from a climber's line. 6. Training and Pruning of Young Trees a) Young trees can be trained to grown into structurally sound trees well suited to the site. These trees will fulfill their intended function sooner, should require little corrective pruning as they mature, and will substantially reduce pruning costs over the life of the trees. Young trees of large, mature size should have a sturdy, tapered trunk with well-spaced branches smaller in diameter than the trunk. 7 b) These standards apply primarily to large-growing, round-headed (decurrent) trees. Trees that will become decurrent seldom have lateral shoots on the current season's growth, such as most Oaks, Elms and Gallery Pears. Early training of central leader trees (excurrent), such as Liquidamber syraciflua and most Conifers may be less important except to remove low branches and those competing with the leader. 7. Trunk Development of Youna Trees a) For most trees maintain a single, fairly straight trunk. Only head the leader if: i. In summer it is very vigorous, then it is desirable to correctly position the lowest main branch or to space other main branches at least 16" or 24" apart vertically (depending on the mature tree size); or, ii. When dormant, to remove a tuft of terminal twigs so that more vigorous shoots can be chosen the next growing season. b) For the first year or two after transplanting a tree, leave more potential main branches than will eventually be needed. This will ensure a better selection of main branches and aid the early growth of a tree. c) Potential main branches can be spaced 6n to 12" apart vertically the first year or two. By the fourth year however, large growing trees should be thinned to from 5 to 9 branches at least 24" apart. First remove the largest of the branches that you know will not be kept. d) Amain branch and other potential main branches should be 1/2 the diameter of, or smaller than, the trunk diameter immediately above the branch. If a branch is too large, thin laterals on it, or if too few laterals, head the branch. 8. Temporary Branches of Youna Trees a) Select small temporary branches along the trunk below the desired height of the lowest main branch and between main branches. It is more important to have temporary branches below the lowest main branch than above to protect the trunk and increase its caliper and taper. Temporary branches should be kept for 2 to 4 years unless they become more than 1/2" in diameter. b) Preferred vertical spacing is 4" to 6". Select the least vigorous shoots for temporary branches. If larger than desired, branches need to be kept as temporaries. Head them back to 2 or 3 buds. It is important to have some temporary branches on the trunk side facing the afternoon sun (equator-west side). The bark and angle of the attachment of temporary branches are not important because they will be removed. c) During the growing season, temporary branches should be kept shorter than 12" inches in length. If still growing, cut back at least by half. Temporary branches may need 2 to 4 prunings during a growing season depending on tree vigor. These prunings can be quickly and inexpensively done and provide opportunities to inspect for other problems. d) At the first dormant pruning, thin out 1/4 to 1/3 of the temporary branches. Leave them uniformly spaced, removing the largest or cutting them back to 2 to 3 buds. At the next dormant pruning, remove about the same number of temporary branches as removed the 8 first year. In most situations, by the fourth dormant pruning, all the temporary branches should be removed. e) One-half of the foliage should be on branches (temporary and main) arising in the lower two- thirds of a tree. This will increase trunk taper and more uniformly distribute branch weight and wind stress along the trunk. 9. Main Branch Selection of Young Trees a) The height of the lowest main branch will depend on the function of the tree; to screen an unsightly view; serve as the wind break; shade a patio; line a street; etc. b) More potential main branches can be left than will be needed to ensure a selection of well- placed and vigorous main branches. Potential main branches should be spaced 6" to 12" apart vertically. By the fourth or fifth year, the main branches in the lower part of the tree should be selected and be at least 12" to 24"apart, depending on mature tree size. c) Select 5 to 9 main branches (3 to 5 on small growing tree) to give radial distribution for light penetration and tree balance. None should be directly over another unless it is 4' to 12' (dependent upon tree size) above the lower branch. 10. Develooina Strona Branch Structure of Youna Trees a) Main branches should be 1/2 the diameter or smaller than that of the trunk immediately above the branch. For strength, the relative size of a branch to the trunk is more than its angle of attachment. b) No main branch attachments should have included (embedded) bark. c) Encourage laterals along main branches, but none larger than 1/2 the diameter of the main branch. The lateral closest to the truck should be at least 2' out on the main branch. 11. Pruning of Mature Trees a) Crown Cleaning or Cleaning Out -Removal of dead, dying, diseased, crowded, weakly attached, low-vigor branches, and water sprouts from a tree crown. b) Crown Thinning -Includes crown cleaning and the selective removal of branches to increase light penetration and air movement through the crown. Increased light and air maintains and stimulates interior foliage, which in tum improves branch taper and strength. Thinning reduces the wind-sail effect of the crown and the weight of limbs. Thinning the crown can emphasize the structural beauty of the trunk and branches as well as improve the growth of plants located beneath the tree by increasing light penetration. When thinning the crown of mature trees, seldom should more than 1/3 of the live foliage be removed. After pruning, at least 1/2 of the foliage should be on branches that arise in the lower 2/3 of the tree. Likewise, when thinning laterals from a limb, an effort should be made to retain inner lateral branches, that is 1/2 of the foliage on laterals along the inner 2/3 the branches. Trees and branches so pruned will have stress more evenly distributed throughout the tree and along the branches. 9 An effect known as lion's tailing results from pruning out (stripping) the inside lateral branches. Lion's tailing, by removing most of the inner foliage, displaces the weight to the ends of the branches and may result in weakened branch structure, limb breakage, sunburned branches, and water sprouts. c) Crown Reduction -Used to reduce the height and/or spread of a tree. Thinning cuts are most effective in maintaining the structural integrity and natural form of a tree and in delaying the time when it will need to be pruned again, thereby reducing maintenance costs. The lateral to which a branch or trunk is cut should be at least 1/2 the diameter of the cut being made. d) Crown Restoration (Renewal) -Can improve the structure and appearance of a tree that has been topped or severely pruned using heading cuts. One to three sprouts on main branch stubs should be selected to reform a more natural appearing crown; all except one will be headed to one or two buds to speed would enclosure. Selected vigorous sprouts may be need to be thinned to a lateral, or even headed, to control length growth in order to ensure adequate attachment for the size of the sprout. Restoration will require several prunings over a period of years. e) Crown Raising -Removes the lower branches of a tree in order to provide clearance for buildings, vehicles, pedestrians, and vistas. It is important that a tree have at least 1/2 of its foliage on branches that originate in the lower 2/3 of its crown to ensure a well formed, tapered structure, and to uniformly distribute stress within a tree. f) Utility-line Clearing -Can combine all 5 types of pruning techniques described above to direct tree growth away from utility lines. Detailed studies or pruning techniques, tree responses, and costs have shown that the above recommended pruning techniques can be used to a trees advantage in utility-line pruning. To achieve clearance, make thinning cuts primarily back to medium-sized branches within the crown. Remove the entire branch if more than 50 percent of live foliage needs to be removed from it. Severe height reduction (including heading) occasionally may be the only alternative where a tree is directly under lines. It may be best to replace the tree. Plant-growth regulators can usually be used to slow the development of many fast-growing species. Vegetation control along transmission right-of-way is usually best done with chemicals. g) View Restoration -Crown thinning, reduction, and/or raising can be used to enhance or restore a scenic view and/or light penetration to the property. Views can be quite attractive when seen through sparsely-leafed branches. Care must be taken not to over-prune. D. Preservation and Infrastructure Consideration Trees are an essential element of the image and quality of life in the City of Tustin. Hardscape elements such as the sidewalks, curbs, gutters and driveways are indicative of the City's commitment to maintaining its infrastructure. Over the years broken and damaged sidewalks, curbs, gutters and driveways will have to be replaced throughout the City. New development and redevelopment wilt also occur. As a result, many trees may be affected. To protect and preserve existing trees the following guidelines have been established: 10 • Whenever sidewalk, curb, gutter or driveway replacement occurs within 4' of a tree, the Public Works Department must inspect the site to determine the potential impact upon the tree. • The City Public Works Department will determine which roots can be safely pruned without jeopardizing the life of the tree. 1. Sidewalk Renovation Trees that would be seriously affected by root pruning during sidewalk replacements must be inspected by the Public Works Department to determine whether: a) The repair work can be deferred and a temporary asphalt patch used to eliminate any hazard until other steps can be reviewed and implemented. b) The tree can be saved by narrowing the sidewalk near the tree, while still leaving sufficient sidewalk width for access. Standard access width is 4', with variances to 3' where absolutely necessary for no more than 2' in the path of travel. c) The tree can be saved by relocating the sidewalk onto private property and negotiating the appropriate easement. d) The tree can be saved by replacing the sidewalk without disturbing the roots (alternatives; temporary asphalt sidewalk, use of root barrier fabric, raising the sidewalk grade over the roots, informal walkway, installation of ground, recycled rubber sidewalk, etc.) e) The tree can be removed and replaced with a minimum 15-gallon tree. 2. Curb and Gutter Reolacement Trees that would be seriously affected by root pruning during curb and/or gutter replacement must be inspected by the Public Works Department to determine whether: a) The repair work could be deferred and would not create drainage problems or otherwise increase street maintenance unnecessarily, and would not be a hazard. b) The tree can be saved by replacing the curb and gutter without disturbing the roots (alternatives: place temporary asphalt in the gutter and/or use of root barrier fabric, etc). c) The tree can be removed and replaced with a minimum 15-gallon tree. d) When 6 or more trees along one side of a block are severely affected, consideration is to be given to relocating the curb and gutter into the street along the entire block. 3. Root Prunin4 a) Root pruning must be carefully controlled to assure tree stability and to avoid exposing the City to liability. b) All roots greater than 2" in diameter must be cleanly cut to encourage good callus tissue. It is recommended that roots be pruned back to the next root node. Obtain the approval of the Public Works Director (or a designee) before the work begins. 11 c) There will be a 36-month delay between sidewalk repair and curb/gutter repair to allow time for tree roots to recover. This work should be done only on one side of a tree at a time. An exception to this policy maybe made if the curb/gutter or sidewalks is relocated away from the tree, or other measures are employed that reduce or eliminate root damage, or it is otherwise determined by the Public Works Department that root damage is minimal. 4. Construction Projects on City Property and/or Riahts-of-way The following guidelines have been developed to protect trees on City property during construction projects: a) Before construction begins that could affect a tree, a signed release must first be obtained from the Public Works Department. Release consideration shall include the condition of the tree and an assessment of the impact of the proposed construction. Mitigating measures necessary to protect the tree will also be stated in the release. b) Aroot-protection zone shall be required. It shall be a 4' high, 2' by 4' barrier constructed around any potentially affected tree. This barrier shall be determined by the City Arborist whose objective is to minimize any damage to the tree and to minimize soil compaction. When ban-iers are not possible for keeping vehicular and foot traffic away from the root- protection zone other protection methods that can be used are the spreading of mulch several inches thick; pumping concrete from the truck through conveyor pipes instead of driving over root zone. c) Should it be necessary to trench within this area, trenches shall be hand dug. Roots larger than 2n shall be hand dug. No roots larger than 2" shall be cut without prior approval of the Director of Public Works or the Director's designee. All small roots that must be cut shall be saw cut (no trenches) flush with the side of the trench. If at any time 25 percent of the area within the root protection zone is being separated from the tree by a trench, the line shall be located by boring the roots, or an alternate location for the trench shall be established. d) The minimum clearance between an open trench and a street tree shall be 1' for each inch of trunk diameter measured at 4.5' above the existing grade if this method defines a larger distance. The maximum clearance shall be 10'. The contractor shall conform to these provisions unless otherwise directed by the City. e) At no time shall any equipment, materials, supplies or fill be allowed within the prescribed root protection zone unless otherwise directed by the City. f) Failure to abide by these provisions will result in substantial root damage to trees that may not be immediately apparent. The City will therefore assess damages according to the International Society of Arboriculture standards and payments to the contractor will be reduced accordingly. 12 E. Tree Removal and Realacement 1. Tree Removal The Public Works Department has developed the guidelines listed below to assist in the determination of whether removal of a tree is warranted and in the City's best interest. In each case, the decision to remove a tree must be approved by the City's Director of Public Works, or the Director's designee. a) Emergencies A healthy tree may be removed in an emergency situation (e.g., to deal with a broken water main) if removal is determined to be the best option. b) Chronic Damage A tree that is determined to be causing chronic and persistent damage to curbs, gutters, sidewalks or other hardscape and structures may be removed. c) Potential Hazards A dead or dying tree that is creating a safety concern may be removed when: i. The possibility of a dying tree or portion of the tree may fall. ii. There is traffic sight obstruction where pruning cannot be performed without severe disfigurement of the tree. d) Insect Infestation or Disease A tree may be removed if it is infested with insects or diseased and if it presents a threat to other trees nearby. Each decision to remove a tree shall be reviewed to assure that suitable pest-control options have been pursued and that a tree is not being removed unnecessarily. e) Resident's Removal Application On a case-by-case basis all applications for tree removals submitted by Tustin residents shall be reviewed by the Director of Public Works, or the Director's designee. In each instance the Director shall determine whether or not such tree is required to be retained in order to preserve the intent and purpose of the Urban Forest Management Plan. In making his/her determination, the Public Works Director or the Director's designee, shall consider the inconvenience or hardship which retention of the tree would cause the property owner and consider also the condition, age, desirability of variety, and location of the tree. If the Public Works Director or the Director's designee finds that the tree may be removed without violating the intent and spirit of the Urban Forest Management Plan, he/she may authorized the property owner to remove such tree at his/her own expense and liability. If an application is approved for removal of a street tree, all removal work shall be completed within sixty (60) days from the date of issuance of the permit, and shall be under the general supervision of, and in accordance with, rules established by the Public Works Director or his/her designee. All tree stumps shall be removed to a depth specified by the Director. All approved removal applications shall be void after the expiration of sixty (60) days from the date of approval, unless extended by the Public Works Director. 13 f) Reforestation Periodically, trees in various parts of the City will be removed and replaced. 2. Scheduled Tree Replacement Program Many blocks in the City of Tustin have been planted with monocultured (i.e., single species) trees. Since the trees on these respective blocks were planted at the same time, they are all the same age (i.e., even-aged). a) These factors make them susceptible to simultaneous decline for two reasons: First, all trees in a monocultured stand are susceptible to simultaneous insect infestation or disease. ii. Second, all trees in a single-aged stand will reach the end of their life spans simultaneously. b) In an effort to forestall conditions of simultaneous decline occurring on the blocks in questions, the City will prepare a 15-year plan as follows: Blocks planted with monocultured, even-aged stands of trees will be identified. ii. A schedule will be devised for replanting those blocks with a mixed variety of trees of varying maturity. iii. Replacement will occur at 5-year intervals. iv. No more than 25 percent of the trees at an involved location will be removed atone time. v. As the transition continues, removal of healthy trees may become necessary to complete each phase. vi. At the end of 15 years, 4 generations of various trees will have been planted on the blocks in question. Streets with historic landscaping patterns will be identified and made exempt from this transition plan. F. Tree Selection Lists and Plantins~ Criteria 1. Tree Selection Lists a) In cooperation with the Community Development staff, the Public Works Department shall develop and maintain a list of trees approved for planting in various sites throughout the City. The list is site-specific. In developing the lists, consideration has been given to: Function purpose(s) of the specifies ii. Adaptability to specific site iii. Amount of care required 14 2. Design Criteria -- Characteristics of Trees In developing the list of approved trees for specific sites, Public Works Department staff takes the following characteristics of a tree into consideration: a) Site Function: • Provide Shade • Buffer Sound • Buffer Wind • Screen View b) Growth Habits: • Tree, Vine or Shrub • Height at Maturity • Spread of Canopy • Form • Rate of Growth • Branching • Strength • Roots c) Features: • Leaves • Thorns • Flowers • Fruit • Bark d) Environmental Tolerance: • Temperature • Drought • Wind • Light • Air quality • Pests 15 SECTION III CLOSING STATEMENT The City of Tustin's tree-lined streets form an urban forest that enhances the health, aesthetics, and quality of life in this community. The City is committed to the management and preservation of this valuable resource through effective utilization of tree inventories, modem horticultural tree maintenance methods, and sound community planning. This plan sets forth guidelines for the maintenance of the tree inventory, planting and pruning of trees, removal and replacement of trees, and furnishes the necessary considerations to preserve the infrastructure affected by the trees. This plan is intended to serve as a resource for selecting, maintaining, and replacing trees in our urban forest. Acknowledgements: Those who have provided information used in the development of this document: • International Society of Arboriculture • The National Arbor Day Foundation • Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines: By Richard W. Harris The City of Upland • The City of Claremont • The City of Pasadena 16