Appendix_E_--_BAFB-Tree_Management_Plan-Final2.pdf

BARKSDALE AIR FORCE BASE

BOSSIER CITY, LOUISIANA

URBAN FOREST SUSTAINABILITY PLAN

December 2004

PREPARED BY:

C-K ASSOCIATES, LLC

17170 PERKINS ROAD

BATON ROUGE, LOUISIANA 70810

(225) 755-1000

C-K ASSOCIATES’ PROJECT NO. 15-0276

Barksdale Air Force Base Bossier City, Louisiana

TABLE OF CONTENTS

Section Page

1.0 INTRODUCTION

2.0 CONDITION ASSESSMENT

3.0 INSTALLATION AND CARE FOR YOUNG TREES

3.1 Tree Selection

3.2 Where to Plant

3.3 Standards for Planting Trees

3.4 Care for Newly Planted Trees

4.0 WORKING AROUND TREES

4.1 Planning and Preparation

4.2 Construction Standards

4.2.1 Guidelines for Tree Protection

4.2.2 Trees Damaged or Destroyed During Construction

4.2.3 Required Removal due to Construction Damage

4.2.4 Historic Tree Preservation

4.3 UTILITY CONCERNS

4.3.1 Overhead Utilities

4.3.2 Underground Utilities

4.4 POST-CONSTRUCTION CARE STANDARDS

4.5 SOIL COMPACTION

4.6 SIDEWALK, ROADWAY, AND DRIVEWAY CONSTRUCTION

5.0 CARE AND MAINTENANCE OF MATURE TREES

5.1 Examination and Evaluation

5.2 Pruning Standards

5.3 Root Care

6.0 PLANT HEALTH CARE

6.1 Insect and Disease Management

6.2 Fertilization

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TABLE OF CONTENTS

(cont.)

7.0 SUMMARY

8.0 ENFORCEMENT

LIST OF FIGURES

Figure

1 High Value Area-Barksdale Boulevard-GIS Map 2 Buckling Sidewalk 3 New Path to Reduce Impact 4 Alternative Measures – Louisiana State University 5 Root/Sidewalk Conflict 6 Soil Disturbance 7 No Root Flare 8 Root System/Sidewalk Conflict 9 Sidewalk Alternate Path 10 Alternate Measures – Sidewalk/Pavers 11 Alternate Measures – Sidewalk/Blocks 12 Urban Setting for Tree 13 Tilling Under Tree 14 Sodding Under Tree 15 Tree Decline 16 Mulched Live Oak 17 Alternate Path for Sidewalk 18 Crape Myrtle Damage 19 Correct Actions – Tree Preservation

LIST OF APPENDICES

Appendix

1 Barksdale Air Force Base Soil Information 2 Barksdale Air Force Base Construction Work Permit

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1.0 INTRODUCTION

The urban forest at Barksdale Air Force Base (BAFB) is comprised of some 7,000 trees dispersed among 1,700 acres. This urban forest is enjoyed by all who live, work or visit BAFB. An Urban Forest Management Plan/Inventory was conducted in 1991 by the Louisiana Department of Agriculture and Forestry. The update to this plan was conducted by Davey Resource Group and World Tree in 1999. The 1999 update introduced a new technology, Geographic Information System (GIS) and Geographic Positioning System (GPS) into the management of the urban forest. This new technology has revolutionized the management and care of the urban forest, not only at BAFB, but in other similar urban forest settings. GIS Technologies allow for easier tracking of schedules, monitoring of the urban forest, and tracking of the maintenance schedules. Through this effort the “Barksdale AFB Urban Forest Map Workbook” was created. It is now the tool used to assist the Urban Forester with management of the urban forest at BAFB.

Barksdale, home to the 2nd Bomb Wing and the 8th Air Force, is situated on approximately 22,000 acres of land in the northwest corner of Louisiana. BAFB is just east of the Texas border and south of Arkansas, in Bossier Parish.

Over 20,000 acres of the base is designated for recreation and includes a game reserve.

Hiking and biking trails wind through the property and both hunting and fishing are allowed. Abundant natural resources are available to accommodate most recreational interests. The majority of the military housing is located on main base, in the Historic District, and is listed on the National Registry of Historic Places along with more than 200 other buildings at BAFB.

The base's namesake is Lieutenant Eugene Hoy Barksdale of the Army Air Corps, who lost his life while flight testing an observation aircraft over McCook Field, in Dayton, Ohio on Aug 11, 1926. Originally designated Barksdale Field in 1933, it was the largest airfield in the world.

This Urban Forest Utilization Plan (Plan) is being developed in-part to accomplish four tasks as outlined in the Statement of Work (SOW) issued on July 14, 2004. In that SOW, the specific tasks identified are:

• Evaluate urban forest sustainability and provide locally specific strategies for sustainable urban forest planning and management.

• Develop tree/urban forest management policies and cost-effective solutions to preserve the safety, health, and appearance of Barksdale’s urban forest.

• Gather site-specific information pertinent to the selection of treatment or management strategies.

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• Provide science-based solutions, design and engineering perspectives for tree-utility conflict avoidance, root system development, root guidance and hardscape resistance.

The Plan will serve as a guidance document to establish recommended arboricultural practices that should be instituted and implemented by the Urban Forester to help ensure the health and vigor of the urban forest at BAFB.

Just as in most urban areas, the urban forest at BAFB is fragmented with trees standing alone or in small groups. Trees are located in the residential yards, public parks, and cemeteries. Many clusters of trees are found at the golf course and in rights-of-way.

In general, the canopy of BAFB’s urban forest is comprised of older established mixed hardwood species. There are high valued live oaks that line either side of Barksdale Boulevard. This area is the dominant feature in the Urban Forest at BAFB and is highly valued and prioritized for preservation.

Trees, like most living organisms, work best in groups where all can share the environmental stress. Urbanized fragmentation of the forest greatly impacts individual trees. Thus, many trees in this situation are often stressed, generally have a shorter life span, and are in need of constant maintenance. There are proactive steps that can be taken to address these environmental stresses, thus increasing the survival rate of each individual tree within the forest community. This plan will outline steps to assist in the care and maintenance of the urban forest at BAFB, identify potential problems, monitor, and provide corrective measures in the battle between “grey” infrastructures

vs. “green” infrastructure. The plan will also provide standards for the care and maintenance of the trees found at BAFB. Public safety and the well being of property coupled with what is best for the trees should be a priority.

In general, we can use the basic requirements of trees that are naturally occurring in forest settings, as guidelines in determining the requirements of an urban forest.

Typically, the urban forest is faced with many environmental stresses not faced by naturally occurring forest. Planning, management and maintenance are tools that an Arborist uses to combat the environmental stresses that urban trees may face.

2.0 CONDITION ASSESSMENT

The condition assessment, sometimes referred to as a site assessment, should be conducted at the onset of any Plan development to evaluate the health and sustainability of the urban forest. The overall health and condition of the forest must be fully assessed in order to develop and maintain a sustainability management plan for your urban forest.

The initial Condition Assessment was conducted through the “Barksdale AFB Urban Forest Map Workbook and Inventory”. This effort has provided a good foundation to

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December 2004 build on. The Urban Forester has a good tool for managing the urban forest. This document should be updated on a regular basis to ensure accuracy. The Urban Forester makes regular site specific inspections assessments in order to update this manual.

In high value areas, or high liability areas, periodic condition assessments should be conducted with a higher frequency. Barksdale Boulevard was identified as a “High Value Area”, the live oaks in this area are of great value and ensuring their survival is vital. Additionally, areas of high traffic and areas of high usage by pedestrians, visitors, and residents of BAFB, should be evaluated at a higher frequency. Typical High Value or High Traffic areas observed and identified are:

• Barksdale Boulevard

• The Golf Course

• Various Parks/Commons Areas

• Recreational Areas

• Churches

• Housing Areas

These areas shall all be inspected on a routine and regular basis. The trees in this area shall be inspected for defects, potential hazards, decline, included bark, insect and disease problems, lightning strikes, decay, crown and root problems, overhanging or problematic limbs, etc. The Urban Forester will identify these areas and set a schedule for inspection to ensure the health and integrity of the trees found in these areas. The Highest Valued area is the Live Oak lined Barksdale Boulevard, Figure 1. Because of the value, this area should be inspected annually by the Urban Forester to ensure the health and vigor of these important trees.

Additional High Value area were indicated during the initial site survey conducted on

3.0 INSTALLATION AND CARING FOR YOUNG TREES

Since BAFB’s urban forest is largely comprised of mature trees, planting new trees will ensure sustainability of the urban forest. These new tree plantings are critical for several different reasons. New (young) trees mixed with mature (old) trees replicates a forest’s natural setting. In a naturally occurring forest, not all of the trees are the same age, size or type. In the urban arena, we should mimic this naturally occurring condition to ensure diversity. Increased diversity will help attract a diverse group of animals and assist in establishing a healthy forest. The older more mature trees will ultimately decline to a point where removal is necessary for public safety. Just as in a naturally occurring forest, when the older trees die, the young trees are already in place to replace the older trees.

A forest that is diversified in age and in species composition is typically healthier, thus it will tend to be less susceptible to insect, disease, and pathogen infestation. In other

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December 2004 words, in a forest that is limited in diversity, both age and species, the effects of pests would be magnified. In this example, all of the trees would be the same species and the same relative age, which yields a monoculture. In general, in plant communities, a monoculture may lead to infestation and possibly destruction by pests.

3.1 TREE SELECTION

Selecting the right tree for the right situation will help to ensure survival of newly planted trees. Many factors go into determining which species is appropriate, such as:

• Soil Conditions

• Exposure (sun and wind)

• Placement

• Drainage

• Space Constraints (all sides, and above)

• Maintenance

The question most frequently asked of tree care professionals is "What tree do you think I should plant?" Before this question can be answered, a number of factors need to be considered. Think about the following questions:

• Why is the tree being planted? Do you want the tree to provide shade, fruit, seasonal color, or act as a windbreak or screen?

• What is the size and location of the planting site? Does the space lend itself to a large, medium, or small tree? Are there overhead or below ground wires or utilities in the vicinity? Do you need to consider clearance for sidewalks, patios, or driveways? Are there other trees in the area?

• What type of soil conditions exist? Is the soil deep, fertile, and well drained or is it shallow, compacted, and infertile?

• What type of maintenance are you willing to provide? Do you have time to water, fertilize, and prune the newly planted tree until it is established or will you be relying on your garden or tree service for assistance?

Asking and answering these and other questions prior to beginning the selection process will help you determine the "right tree for the right place."

Soil condition is the first factor that should be considered. A soil map should be used to properly identify the soil type of the area to be planted (understanding, that in most urban situations, fill material and grading has occurred, so the

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December 2004 naturally occurring soils have been displaced or altered, a result of urbanization). The soil type will dictate which species occur naturally in that area. Furthermore, soil type coupled with other factors such as soil pH, will indicate which species may have the highest potential for survivability.

A soil survey was used to gain a better understanding of the particular types of soils found a BAFB. The United States Department of Agriculture Soil Conservation Service’s Soil Survey for Bossier Parish, Louisiana, 1962 was studied to gain an understanding of the naturally occurring soils in this area.

See Appendix 1-Barksdale Air Force Base Soil Information.

Based on this soil survey that was conducted, several trees could do very well at BAFB. Some of the trees that should be considered for future planting are:

• Nuttall Oak

• Cherrybark Oak

• Cottonwood

• Sweet Gum

• Overcup Oak

• Sweet Pecan

• Elm (American and Winged)

• Bald Cypress

• Willow Oak

• Cedar Elm

• Green Ash

Exposure is another factor that should be considered prior to selection.

Consider the climate trends of the region and also the specific site that the tree will be planted. Is the tree planting site on the west or the south of the property? What are the requirements of the tree? The regional climate trends, temperature, rainfall and associated information are all compiled to produce climate zones. Climate zones are used as a guide to assist in plant selection.

Placement is another factor to consider. Where is the tree planting site specifically located? Is there high traffic? High traffic areas can usually lead to soil compaction issues. Also, as the tree matures, the tree will begin to drop flowers are fruit. If the tree is in a high traffic area this could cause a slipping or tripping hazard. Mature trees often shed branches, which could lead to injury if the tree is planted in a high traffic area.

During the selection process, gain an understanding of the space that the selected tree may require as it grows. There are fundamental differences in growth for each species. Compare the difference in growth, in terms of space required, for evergreen trees and deciduous trees. Make plans for the shape and space that the tree and its root system will require at maturity. Consider the

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December 2004 space at the time of planting and also future plans for development that may intrude on the tree’s space. Space trees out for future growth of the tree and plan for future development, and your planting will have a greater chance for success.

Maintenance of the tree is a factor that is commonly overlooked. The maintenance plan should be an integral part of the planning process. Even well designed and planned projects require proper resources for maintenance. Often times, the focus is placed on the planting or the planning and the aftercare program is neglected. This leads to unsightly projects just months after installation that require more capital to salvage the project.

Consult a professional Arborist during the tree selection process. This will ensure that important factors are considered during the planning stages. Often, tree-planting plans are made and implemented without considering every issue.

This sometimes leads to over spending, over planting, poor plant selection, and mortality of the newly planted trees or public safety issues. Proper planning with a trained professional Arborist may help to ensure the proper tree is selected and may help to reduce future maintenance expenses and headaches.

3.2 WHERE TO PLANT

Once the species has been selected, site-specific conditions should be considered before planting such as utilities, space, future development, full sun or shade.

Equally as important as tree selection, placement of the tree is critical in reducing the stress that the tree may bring to the community.

Identification of the underground utilities, and properly marking them, should be a primary consideration in deciding where to plant. Underground utilities are buried at different depths. Consult the city engineers or the utility company prior to excavating for the tree planting. Also look at the above ground utilities.

Be familiar with the codes and standards in your area. Most utility companies have a clearance standard. Planting trees within the right-of-way may result in added expense for the taxpayer, maintenance concerns, public safety issues and an unhealthy tree situation.

To ensure the selected tree has adequate space, consider the size of the tree at planting and the size of the tree at maturity. When considering the space, remember that the roots need adequate space. Most trees are larger below ground than they are above the ground. Give the tree space to grow. If there is restricted space, then consider planting a different species or not planting in this location. Also, consider the drainage pattern of the site. Understanding the soil type and the topography for the area may indicate drainage. Poor drainage can lead to suffocation of the root system, while rapid drainage may not allow the

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December 2004 tree’s roots time for adsorption. Consulting a professional Arborist may reduce the likelihood that the tree is planted in an unsuitable area, thus reducing the maintenance cost for all parties including the taxpayers.

Trees that have been planted in an unsuitable situation can be found in almost every public right-of-way. These trees tend to be problematic in terms of maintenance and likewise, public safety. Trees that are problematic will require constant attention. From breaking up sidewalks and roadways to interfering with power lines and causing power outages, trees planted in the wrong spot can prove to be costly to the public.

3.3 STANDARDS FOR PLANTING TREES

There are several steps that need to be followed to ensure that the tree is being planted properly. Trees shall be planted in accordance with the American Association of Nurserymen, Inc. (ANN) Standard: American Standard for Nursery Stock (ANSI Z60.1, latest edition). Before the execution of any planting project, the Urban Forester shall be consulted to ensure the proper tree is planted in the proper place and to evaluate the condition of the tree as it arrives form the nursery. The steps to planting are as follows:

• Inspection- Inspect the tree upon delivery from the nursery. Check the root system, making sure that the roots have ample space and are not constricted. Examine the trunk for straightness and wounds. Look at the crown of the tree. Check for broken limbs. Look closely at the main stem of the tree. The tree should have a single main central leader.

Look for stress fractures or weak points. If the tree does not meet the required specifications, return it to the nursery.

• Site Location- Select a site that will have maximum value, but minimal impact. That means, plan the right tree in the right place. Consider the tree’s size at maturity. Place the tree in a place that will not cause conflict with the surroundings (utilities, buildings and other infrastructure). No dominant tree shall be planted within 16 feet from a major structure.

• Hole depth- The planting hole should be dug to a depth equaling the root ball and approximately 3-5 times wider than the root ball.

• Excavation- The soil that is removed from the planting hole should be placed adjacent to the hole and mixed with a planting soil mix. After the new tree is set in the hole, use this mix to backfill.

• Placement- Place the tree into the hole. The soil line on the tree (where the soil meets the trunk) should be slightly (1-2 inches) above the surrounding grade. Make sure that the tree has been placed in the center of the hole. It may be necessary to loosen the tree’s roots. The root

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December 2004 collar should be minimally visible upon final grading. Step back from the tree and observe from all sides, checking for straightness.

• Backfill- The soil that was removed and mixed with planting soil mix during the excavation step should be used to fill in around the tree’s root system. Tamp the soil down slightly, enough to assist the tree in standing upright. With the excess soil construct a 3” tall berm that encircles the hole. This berm will assist in holding in moisture during watering or during rain events.

• Staking- Using guy wire hose and stakes, stake the tree to assist the tree in maintaining an upright and straight position. Use the hose to guard against rubbing on the bark by slipping the hose over the wire where the wire may come in contact with the bark of the tree. The hose acts as a cushion and protects the tree from sustaining damage from the wire rubbing. Resist the urge to tighten the wire so tightly as to not allow any movement by the tree. The tree’s root system will be stimulated to grow by a gentle swaying action. Staking too tightly will prohibit swaying.

Only allow staking to remain for ninety days after planting, given that the tree is progressing at a normal rate.

• Mulching- Mulch the tree after planting. This will help to retain moisture for the root system and act as a deterrent for weed growth.

Mulch to a depth of 2-3 inches, in the root zone area.

• Watering- Water the tree after the mulch has been applied. Newly planted trees need to be watered often. Tress should receive watering approximately every other day during the growing season. DO NOT

FERTILIZE DURING FIRST YEAR.

3.4 CARE FOR NEWLY PLANTED TREES

Newly planted trees require attention and care to ensure survival. Moisture is the number one limiting factor for newly planted trees. Watering is also critical to established trees as well, although if the tree is well established and is not or has not sustained substantial root damage, the larger roots will seek out moisture. Supplying trees with adequate moisture can happen several different ways.

The most convenient way for a tree to receive moisture is rainfall. However, this is unreliable and in the times of drought, the trees can sustain a tremendous amount of damage.

Mechanical watering systems are another method to supplying trees with adequate water. This is very effective and highly recommended when installing a new planting. However, it is costly and not applicable in all situations.

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Selecting somewhat drought hardy trees and planting in groups seems to be an effective way of proactively addressing the watering situation during the planning stages. Clustering or grouping trees together creates shared responsibility among the trees. The trees tend to shade one another and reduce the evaporating effects of a prevailing wind. Simply, trees planted in groups respond to the environmental stresses by sharing some of the environmental forces that act upon them.

Select trees that are native to the area that you are considering for your planting.

By identifying trees that are adapted to the moisture conditions of the associated area, you will be identifying trees that are tolerant of the moisture patterns of that area.

Mulching is beneficial to newly planted trees. Again, to mimic a natural setting for trees that are found in a forest, the forest floor is made of mulch. Some of the benefits to mulching your trees:

• Moisture Retention- Mulch has the capacity to hold moisture and release that moisture over a period of time. If we were to compare two trees in the same environment, one with mulch and one without mulch, the moisture of the soil associated with each tree would be dramatically different. The soil associated with the tree with mulch would have higher moisture content than the soil associated with the tree without mulch. Understanding that moisture is a desired but limited resource for many urban trees, mulch is important.

• Soil Compaction- In many cases, soil compaction can be greatly reduced to the point of almost no impact. Soil compaction is often overlooked in terms of new construction or new development. The root systems of trees are a sensitive, complex, network of “feeder” roots and “structural” roots, all of which are equally important to the tree’s survival. The addition of mulch under a tree canopy on top of the root system will displace outside forces that may cause soil compaction. Also the mulched area makes a desired home for the earthworm. Like many burrowing arthropods, they can improve the rooting environments for plants and increase the amount of water that soaks into the soil and decrease the soil compaction. It is important to only apply a moderate amount of mulch (3”-4”) in the root zone. An excessive amount of mulch can cause more harm than good.

• Nutrient Replacement- Over time, mulch will begin to decompose and release nutrients back into the soil. Think of a fallen log in a forest.

The minute the log hits the ground, insects, moisture, and time begin to break the log down into useable forms of energy for the surrounding

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December 2004 plant and animal community. The same is true for mulch. Mulch placed under trees, will release much-needed nutrients and as a result feed the trees in small amounts, frequently. Mulch will also act as a buffer that will balance the relative local pH of the soil associated with the tree.

There are several different types of mulch material that can be used as “mulch”. Here is a list of some common types and a brief comment on each.

• Hardwood chips- for use around hardwood trees; good mulch.

• Pine bark chips- for use around acid loving plants; good mulch.

• Pine needles- for use around acid loving plants; great mulch.

• Pea Gravel/lava rocks- adaptable to several different situations.

• Pine bark nuggets- for use around acid loving plants; floats in rain.

• Compost pile mulch- great mulch; FREE.

• Cypress mulch- for use around acid loving plants; floats in rain.

• Grass clippings/Hay- too green; add to compost pile, then use.

4.0 WORKING AROUND TREES

4.1 PLANNING AND PREPARATION

Every successful project begins with proper planning and preparation. It is critical to be prepared prior to the kick-off of the project, and the best way to ensure preparedness is planning. During the project conception, the project manager shall communicate the intent of the project to the Urban Forester and should select a site that will have little to no impact on infrastructure, grey or green. The Urban Forester at BAFB will be able to help in this effort, and thus, the value of consulting with the Urban Forester. Prior to construction, a Construction work Permit must be completed by the Urban Forester along with the Project Manager and the Construction Supervisor, Appendix 2.

Construction equipment can injure the above-ground portion of a tree by breaking branches, tearing the bark, and wounding the trunk. These injuries are permanent, and if extensive, can be fatal.

The Urban Forester shall be consulted on every project, to ensure that the impact to the urban forest will be minimized. The Urban Forester shall be an integral part of the planning and completion of each project at BAFB where there is a potential for impact to the urban forest. Trees are unlike other components in the infrastructure, they are living organisms. They have tremendous value to BAFB and require a great deal of care.

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4.2 CONSTRUCTION STANDARDS

As mentioned previously, planning is a critical step to ensuring the health and survivability of the trees in your project area. Being involved in this stage of the project will ensure the proper steps are taken to protect any green spaces or trees during construction.

4.2.1 Guidelines for Tree Protection

The Contractor shall adhere to the following tree protection measures on all construction/building sites:

1. Prior to construction, all Protected Trees, as determined by BAFB Urban Forester shall be clearly marked and inventoried;

2. A protective fence shall be erected around each Protected Tree or group of Protected Trees at least beyond the drip line of each identified tree;

3. During construction, no access is permitted within the protective fence for any purpose except for cleaning trash that may have collected with in the area, unless approved by the Urban Forester;

4. No attachments or wires of any kind, other than those of a protective nature and approved by the Urban Forester, may be attached to any Protected Tree;

5. Any grade changes, retaining walls, tree wells, or other construction that may alter the hydrology or that could have an impact on the moisture retention of the soil in the root zone, shall be approved by the Urban Forester;

6. All plant material shall be maintained in a healthy and growing condition, and must be replaced if damaged or destroyed according to Section 4.2.2 of this Plan.

7. All protected areas shall be kept clean and clear of debris, trash and excessive weeds.

Additionally, it may be a good idea to collect a soil sample prior to construction. It is recommended that several samples be taken, surface and sub-surface, from random spots within the construction area. These samples can be analyzed to give you a base line for the soil that is on site and its condition prior to construction. Post-construction, additional soil samples can be taken and compared to the base line.

Sampling for soil density, will give an indication of the soil’s compaction rate. As the compaction of the soil increases, pour space decreases, and as the pour spaces decrease, so does the soil’s ability to hold moisture and that reduces the root’s ability to penetrate the soil and grow. It is

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December 2004 important to reduce the impact of the construction equipment on the site.

Soil compaction not only hurts the roots of existing plants, it impacts the area for young or future plantings.

4.2.2 Trees Damaged or Destroyed During Construction

Trees may get damaged as a direct or indirect result of construction activity that occurs near the Protected Tree. For every tree damaged during construction, the contractor shall be required to plant Replacement Trees as follows:

• All Replacement Trees shall be planted in accordance with the American Association of Nurserymen, Inc. (ANN) Standard:

American Standard for Nursery Stock (ANSI Z60.1, latest edition).

• Trees 0-5 caliper inches at the beginning of construction shall be replaced with the same species and the same size of the damaged, destroyed or removed tree.

• Trees 6-12 caliper inches at the beginning of construction shall require the replanting of replacement trees equal to 1 ½ caliper inches for each caliper inch damaged, destroyed or removed.

Replacement Trees shall not be less than 3 caliper inches, and shall be the same species as the original tree.

• Trees 13-24 caliper inches at the beginning of construction shall require the replanting of Replacement Trees equal to 2 caliper inches for each inch removed. Replacement Trees shall not be less than 3 caliper inches, and shall be the same species as the original tree.

• Trees over 24 caliper inches that have been damaged, destroyed, or killed as a result of construction activities shall be the sole responsibility of the contractor. The urban forester will assess the tree’s value based off of the current version of the “Guide for Plant Appraisal” authored by Council of Tree & Landscape Appraisers. The contractor shall replant and replace trees, according to the Urban Forester equaling the appraisal of the lost tree. The Replacement Trees shall equal or exceed 3 caliper inches and shall be the same species as the original tree.

4.2.3 Required Removal due to Construction Damage

No person, directly or indirectly, shall destroy, remove or effectively destroy through damaging any tree on BAFB without first obtaining a Tree Removal Permit, as provided in this section.

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The Urban Forester must issue a Tree Removal Permit for a Protected Tree Removal. In the event that a tree is damaged, the Urban Forester will examine the tree and assess the condition and issue his findings, if the removal is required as a direct result of the contractor’s negligence, then the permit will be expedited and the contractor will follow the Replacement Tree Provisions described in Section 4.2.2

4.2.4 Historic Tree Preservation

The Urban Forester will properly identify and mark all Historic Trees for preservation prior to any construction activity. This would include trees that are greater than 24 caliper inches and/or trees of significant value, as determined by the Urban Forester.

4.3 UTILITY CONCERNS

4.3.1 Overhead Utilities

Overhead utilities are easy to identify, but are often overlooked. During the planning of a project, the Project Manager should determine the presence of any the aboveground utilities. The planners should be familiar with the codes and standards in that specific area. Most utility companies have a clearance standard. Planting trees within the right-of-way may result in added expense for the taxpayer, maintenance concerns, public safety issues and an unhealthy tree situation. Some example trees that can be considered “above ground utility friendly” and can be planted in or near the right-of-way without causing major impact would be:

• Crape Myrtles

• Wax Myrtles

• Japanese Magnolia

• Sweet Olive

• Dogwood

• Hawthorne sp.

• Red Bud

• Grancy Grey Beard

• Yaupon

Generally, when selecting a tree that is to be planted within the right-of-way, and specifically under or near overhead utilities, a tree should be selected that is less than 25 feet tall at maturity. The utility company should be consulted prior to any planting. Additionally, underground

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December 2004 utilities should be marked to ensure that the underground utility is not struck, as this could cause injury or a disruption in service.

Overhead utilities do not seem to be an issue at BAFB. Most of the utilities found on site are underground. There are a few areas that overhead utilities were observed, but there were no observed issues with overhead utility and tree conflicts.

4.3.2 Underground Utilities

Proper marking and identification of the utilities, especially underground utilities, should be a primary consideration in deciding where to plant.

Underground utilities are buried at different depths, also some utilities are buried encased for safety and some are bare. Consult the utility marking or the utility company prior to excavating. Gain an understanding on what type of utilities may be in the area, buried depth, and whether encased or not encased.

The digging and trenching that are necessary to construct a house and install underground utilities will likely sever a portion of the roots of many trees in the area. It is easy to appreciate the potential for damage if you understand where roots grow. The roots of a mature tree extend far from the trunk of the tree. In fact, roots typically will be found growing a distance of 1-3 times the height of the tree. The amount of damage a tree can suffer from root loss depends, in part, upon how close to the tree the cut is made. Severing one major root can cause the loss of 5- 20% of the root system.

In the case where utility-related work is being performed and an existing tree is in the servitude there are ways of causing minimal damage to the root system that will reduce impacts that may cause decline or death to the tree in question. There are a few methods that are used to install utilities into the ground around a tree’s roots:

• The traditional methods of trenching damages and destroys the roots of trees in the immediate area and all roots to the outside of the trenching area due to severing of the root system. To reduce the impact of trenching in the root zone, push to trench to the outside of the root zone. Tree roots that are severed that are 1” in diameter or under have great potential in recovering once they have been cut. In many cases, roots under a 1” diameter respond by sending out many smaller roots from the cut root. Since large roots’ major task is to act as anchoring points for trees, the

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December 2004 stability and structural integrity of the tree is immediately impacted because of a severed root.

• Directional Boring is another method that is widely used in installing underground utilities near the root zone of a tree.

Directional Boring sends the utility under the tree’s roots, therefore bypassing the tree’s roots and causing minimal damage.

Historically, this method has been questioned because many believe the myth that trees have a “Tap Root”. The fact is that saplings display this characteristic, but mature trees do not. The misconception is that tree’s roots are an exact copy of the tree’s limbs. It is a fact that roughly the same amount of biomass that is above the ground can also be found below the ground for most trees. This may vary based on soil type and topography, but generally this rule can be applied. Directional Boring is costly, but does the least amount of damage to a tree’s roots.

• Avoidance of any tree roots is the best way of reducing or eliminating any impact to the tree’s health and integrity. Many times this is not a viable option. In that case, the Urban Forester will be able to offer assistance in the planning stage. It could be that the tree that is going to be affected by the utility work is unhealthy or in need of removal. The Urban Forester working closely with the Project Manager will be able to properly assess the health and condition of all trees within the potential route and offer advice on the proposed route and its potential impact to the trees.

Many land owners get confused on ownership issues as it pertains to right-of-way property and may unknowingly intrude on this space. To determine ownership, property lines must be evaluated and considered.

Open communication and planning between the Project Manager, the contractor, the landowner, and the Urban Forester should occur prior to excavation. This added effort may help to reduce the number of trees that are planted in the right-of-way, thus reducing maintenance expenses and public safety issues.

4.4 POST-CONSTRUCTION CARE STANDARDS

Once the project is complete and the construction equipment has been removed from the area, a post-construction evaluation will occur. The Urban Forester shall inspect all fenced areas that were installed around protected trees and historic trees. An inspection will be made to ensure the trees or the green spaces have been protected to the fullest extent possible.

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During the inspection the Urban Forester will evaluate for:

• Properly maintained fencing, as per the pre-construction discussions and plan.

• Any spilled material that could have detrimental impact to the surrounding vegetation or community.

• Any damage that may have occurred to the crown or the limbs of a tree adjacent to the site or within a protected area.

• Properly disposed trash, none left on site.

• Properly graded soil to ensure proper site drainage.

The effect of construction may not bee seen in the trees until several years after the construction is complete. It may appear that the trees are in great condition post-construction; however, this may not be the case.

4.5 SOIL COMPACTION

Soil compaction occurs when excessive traffic, by foot or by equipment, takes place in the root zone. Soil compaction is best explained by understanding that soil functions much like a sponge. The soil is comprised of air pockets and spaces that get filled during rain events or times of high water. Compaction compresses the soil and forces the particles to be stacked closer together, thus removing the soil’s water retention potential. If the soil has been compressed and cannot hold water, then roots get deprived of moisture.

An ideal soil for root growth and development is about 50% pore space. These pores, the spaces between soil particles, are filled with water and air. The heavy equipment used in construction compacts the soil and can dramatically reduce the amount of pore space. This not only inhibits root growth and penetration but also decreases oxygen in the soil that is essential to the growth and function of the roots.

Most people are surprised to learn that 90% of the fine roots that absorb water and minerals are in the upper 6-12 inches of soil. Roots require space, air, and water. Roots will grow best where these requirements are met, which is usually very near the soil surface. Piling soil over the root system or increasing the grade will smother the roots. It only takes a few inches of added soil to kill a sensitive mature tree.

Soil compaction is often overlooked in terms of new construction or new development. In many cases, soil compaction can be greatly reduced to the point of almost no impact. The addition of mulch or specially designed ramps can be used to combat soil compaction during construction. A tree’s root system is a sensitive, complex, network of “feeder” roots and “structural” roots, all of

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December 2004 which are equally important for the tree’s survival. It is important to only apply a moderate amount of mulch (3”-4”) in the root zone. An excessive amount of mulch can cause more harm than good.

Not only would the addition of mulch in the root zone assist in displacing outside forces that may cause soil compaction, mulched areas make a desired home for the earthworm. Like many burrowing arthropods, they can improve the rooting environments for plants and increase the amount of water that soaks into the soil and decrease the soil compaction.

There are several accepted methods for alleviating or reduce soil compaction:

• Air Fracturing- This is a method that uses an implement that forces pressurized air into the ground cause the soil to separate or fracture.

This is a very aggressive activity, but very effective. There are two types of Air Fracturing that are currently used today:

o Air Spading-blows soil away from the roots and the soil can be amended or altered and returned to the area with many more voids for air, water and nutrients.

o Grow-Gun- This method of fracturing happens by injecting air at the sub-soil level with a tool, air is blown under the soil surface, and many pockets of air are created within the root zone. Typically, these pockets of air can be filled, with the grow-gun with a material that resists compaction.

• Mulching- It is very common to apply mulch topically, and that will aide in weight distribution. There are several types of mulching specifically aimed at reducing soil compaction.

o Horizontal Mulching- The addition of mulch horizontally, or over the top of a protected area.

o Vertical Mulching- The application of mulch in a vertical direction. This method requires digging or trenching in a high compaction area the holes or trenches are then backfilled with some type of mulching product. This will insure that the area has been “broken” and the soil compaction level is reduced.

o Radial Mulching- This type of mulching occurs in the root zone area and requires planning and skill to accomplish to cause maximum benefit and minimum harm. Radial trenches are dug extending from the base of the tree outward and then filled with mulching materials. This is an aggressive, but effective method of reducing or eliminating soil compaction within the root zone.

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The best way to minimize soil compaction is to fence off the protected area or trees to eliminate the construction equipment from entering into the area. The Urban Forester can establish protected areas around sensitive areas throughout the work area. During the site evaluation period, the trees should be evaluated for stability, vigor and integrity. The trees that have been selected to remain shall be fenced by the contractor under the direction of the Urban Forester.

4.6 SIDEWALK, ROADWAY, AND DRIVEWAY CONSTRUCTION

Understanding the root system of a tree and proper planning prior to construction may help maintain the integrity of the root system of trees that are in close proximity to the construction area. The most convenient and appropriate time to protect the root system of a tree is during the planning stages of a construction project.

Many times, property with a high density of trees is selected for a new building or a new project. Appeal, location, value and other factors may be the motivation for selection of a construction site. However, many contractors, planners and developers do not fully understand the difficulties in developing close to trees. Some builders and contractors, to avoid delay and added expense, choose to remove all vegetation prior to construction. Unknowingly, this creates many more problems than keeping the vegetation on the site. Storm water run-off along with increase in future electrical costs and decreased property value are a few of the problems created by removal of the associated vegetation. Some builders, planners and developers are beginning to understand the importance of retaining as much of the native vegetation as possible.

Retaining the native and naturally occurring vegetation requires consulting a professional Arborist, planning, and cooperation. During the planning stages the developers should survey the property with a professional Arborist. The developers, with his plan in hand, along with the Arborist will layout the property and select trees that are to be protected during construction. Protective fencing should be placed around the root systems of the trees that are to remain.

Also prior to fencing, it is a good practice to inject mycorrhizae around the perimeter of the fencing, focusing on the non-construction side, if possible.

This will stimulate new root growth and aide in recovery for any roots that may be damaged or lost during construction.

Mycorrhizae are a naturally occurring fungus that co-exists with healthy, growing roots. These fungal spores can be applied in several manners during several different periods during the growing season. It is best to apply this material prior to the construction work, to the opposite side of the construction

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December 2004 activity, and in conjunction with crown pruning of the potentially impacted trees. This will ensure that the root system is prepared for the trauma of the construction activity. The mycorrhizae will attach itself to the root system of the target tree and help the tree to collect moisture and assimilate nutrients, and off-set the root loss that will occur close to construction. Fertilization is not recommended at this time.

Watering and regular maintenance should be considered for the trees during construction. It is common to scale down, or to restrict the amount of pruning during times of construction. Once construction has been completed, pruning should resume. Continue to monitor and evaluate trees for any decline in health.

Sometimes it will be necessary to construct within the root zone. Several accepted methods exist that reduce the impacts of construction damage.

Avoiding roots is the preferred approach. This may require altering the desired path, but will ensure that roots have been avoided. Avoiding the root system will not only help the tree, but it will also reduce future maintenance on the path, caused by root expansion. Figure 2 shows how a mature live oak’s roots can cause the sidewalk to buckle and become a tripping hazard. In this case, there a few acceptable approaches:

• Repair the sidewalk and root prune or shave the roots and replace the concrete walkway, or

• Remove the sidewalk and move it to an alternate path, Figure 3

• Repair unevenness on the sidewalk by patching or ramping, that is to take small amounts of concrete and fill in the unevenness to reduce the tripping hazard.

Root pruning or root shaving is a relatively new method used to reduce the impacts on the root system as it relates to roadway or sidewalk construction.

Root pruning requires that the roots be cut away from the construction area.

Typically, this method is best when followed by installing a root barrier between the root system and the path. The root barrier will repel roots that grow toward the path. Additionally, in preparation of this type of accepted arboricultural activity, mycorrhizae should be added to the soil around the trees that may be impacted to stimulate and encourage root re-growth.

It is always a good practice to inject the root system with mycorrhizae. This will help off set the loss to root system, by building up areas that are away form the impact area. While some of the root system is being impacted by construction, another area is being stimulated. Since, there is a balance between the root system of a tree and the crown of the same tree, both parts of the tree must have balance for a tree to exist in a healthy state. When a project requires

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December 2004 removal of portions of a root system, then the crown of the tree should be pruned to achieve balance.

Root shaving is a practice that is used to reduce the grade elevation in a construction area. This practice is used when the path must go over a large root. The root is shaved down, not severed, to an elevation that is acceptable for construction.