June 12 -3, 2014 Rogers Historical Museum Annex Rogers, Arkansas Image is Everything • Trees Create the Right Image • Trees Soften Harsh Building Lines and Streets Think Canopy A mature tree produces far more environmental benefits than a young one, and a lush cover of tree canopy produces the best benefits of all. Planning is Critical Soil Volume: Why is it Important? A tree’s ability to grow and stay healthy is largely dependent on available rooting space. If the tree roots cannot expand into the surrounding soil, they will continue to grow in the tree box until they have filled up the available space. When the needs of the tree exceed the capacity of the soil, the health of the tree will begin to decline and it will eventually die. Tree Roots – where they are? •90% of all tree roots are in the top 18 inches of soil •Roots extend 2-3 times beyond the canopy •Feeder roots are located in the top 2-4 inches Drip-line? The drip-line is sacred ground for tree protection What is CRZ? CRZ or the critical root zone is the area under the tree where roots must be protected to insure its future survival. The area where no construction activities are allowed. Different states and cities specify different minimum CRZ’s so be sure you refer to local ordinances before initiating a tree protection plan. Examples: - Some consider the CRZ to be the soil area from the drip-line to the trunk. - Another says to protect a root area equal to 1 foot out for every 1 inch of trunk d.b.h. Therefore, a 60 inch d.b.h. tree would have a CRZ out 60 feet. - Dr. Coder from UGA recommends we protect a root area 2 ½ times the diameter at breast height. ex. 60 inch dbh means the CRZ would be 150 ft. out. BEST IDEA – protect the maximum root area allowed! What’s Beneath the Bark CONSTRUCTION DAMAGE Factors That Affect A Tree’s Tolerance to Construction Activity Small size trees are typically more tolerant than larger sized trees Young trees are typically more tolerant than mature trees Species vary in tolerance Weather at the time of construction TYPES OF CONSTRUCTION DAMAGE Physical Wounds Removal of large areas of bark and cambium reduces tree vigor. Large wounds seal or close very slowly and are open to insects and/or disease. Improper pruning or branch breakage also lead to open wounds. Activities That Cause Indirect Root Damage Soil Compaction Causes: Running of heavy equipment over root zones Piling of debris on top of tree roots Parking the construction trailer under a tree Soil Contamination Prevent soil contamination that can damage or kill trees! - Watch out for fuel leaks. - Do not allow on-site paint dumping. - Plan for cement or mortar wash out areas. Moisture Stress May be from changes in the soil grade, cut outs or soil fills. Could be from soils being too compacted. Possible from changes in drainage and grading. Either way - trees can end up too wet or too dry and not be able to adapt. Soil Fill Impacts of Fill Gas exchange is eliminated which is essential to tree function because roots, during the process of respiration, utilize O2 present in soil macropores and in turn, release CO2 . Anaerobic conditions develop when exchange is inadequate, causing roots to loose their ability to absorb nutrients and water and to lack the vigor necessary for new soil exploration. Can lead to disease and decay in the root crown by holding moisture around the trunk. Die back and death of tree may occur Excavation for Utility Lines Soil Cut Outs Remove vital feeder roots that pick up nutrients and water. Eliminate the nutrient rich topsoil. Damage major roots and opens them to pest entry. Often lowers the water table. Symptoms of Construction Damage Trees with fewer and smaller leaves Trunk sprouts Visible wounds or decay fungi on trunks, and branches Yellowing or browning leaves Denuded branches and dead trees Damage can occur quickly or over a number of years (5-7 years). CONSTRUCTION DAMAGE Tolerant Species White Pine Eastern Redcedar Green Ash White Ash River Birch Boxelder Eastern Cottonwood American Elm Slippery Elm Hackberry Honeylocust Black Locust Red Maple Silver Maple Bur Oak Red Oak Intermediate Species Sensitive Species Black Oak Catalpa Black Cherry Kentucky Coffeetree Hawthorn Bitternut Hickory Basswood Sugar Maple Pecan Pin Oak White Oak PROTECTION TECHNIQUES Tree Protection Plan preventing damage to saved trees Protect desirable trees – good species, large specimens, historic trees etc. Protect the critical root zone which runs from the base of the trunk at least to the drip line if not beyond. What’s involved in protection? Deciding which trees to save Should be done in preliminary protection plan. Based on location, health, size, species, etc. Plan developed by a certified arborist – a professional. THIS ONE WORTH SAVING? Protect Groups of Trees Identify and select land protection options Use zoning and subdivision ordinances •Determine type of development •Residential •Commercial •Institutional •Consider woodlands and tree protection options Tree Ordinances Install Protective Tree Fencing Around Critical Root Zone Fences separate trees from construction activity Leave natural areas and protect groups of trees when possible Tree protection area should be installed outside the critical root zone Raise the canopy to reduce the potential of damaging lower branches Installing utilities and pruning roots using an air spade •design Tunneling is the better option Recommend 3 feet deep Keep utilities together when possible After GeoRunner Mats Distribute the Weight Tree Wells Tree wells can be effective if you have enough space to get them in. They should ideally be located at the drip-line or beyond to protect the critical root zone (CRZ). Symptoms and Signs of Construction Damage Crown- slow rate of growth and dieback Tree Evaluation Can Help Save Big Trees Site and Tree Evaluation 1. The purpose of the site evaluation is to identify trees at the construction site to save, remove and/or transplant. 2. If site plans have been developed, use the plans to see what trees are to be impacted and look for ways to minimize the damage. Site and Tree Evaluation Information to Collect Tree Age- Mature trees have instant canopy; younger trees more resilient. Tree Health- Good structure and form with no insect, disease problems, etc. Tree Species- Species with best chance of surviving and still maintain diversity. Critical Root Zone- size should be adjusted according to specific tree and site factors. Alternative Methods To Clearing Barko 930 Industrial Tractor Before and After Reduces heavy equipment damage and allows for remote access Reduces the need for burning or chipping Reduces the cost of hauling and disposing of debris Creates a park-like effect while leaving a highly desirable, nutrient-rich mulch behind Design Features Infrastructure Together Framed Sidewalk with Rubber fill in Little Rock Bioswale Urban Forestry Watershed Manual Silva cells are plastic structures designed to be filled with soil and covered with pavement. Tree roots grow in the uncompacted soil between the structural supports (left, image courtesy of Deep Root Partners, LP). Structural Soil Structural soil, a mix of stone and soil (left), was developed to support pavement, pedestrian and vehicle loads while maintaining the void space required for tree root growth. It is placed in the area to be covered and compacted during the construction process. Tree roots grow through voids between the stones (far left, image courtesy of Urban Horticulture Institute, Cornell University). Olympia Structural Soil Demonstratio n Project Structural Soil delivered and installed Olympia Structural Soil Demonstratio n Project Structural Soil Being spread with an excavator Olympia Structural Soil Demonstratio n Project Sidewalk demolished, existing soil excavated Olympia Structural Soil Demonstratio n Project Geo-textile fabric before top-course is installed Olympia Structural Soil Demonstratio n Project Ready to pour concrete Olympia Structural Soil Demonstration Project Project Site, Before Olympia Structural Soil Demonstratio n Project Project site, trees installed Looking East Storm Water and Heat Island Reduction Structural Soil - Fayetteville 1980 2007 Trees on Pennsylvania Avenue NW, in Washington, DC have grown to different sizes several years after planting (left, image courtesy of Urban Horticulture Institute, Cornell University). Trees along the street have about 300 cubic feet of available soil under the pavement, while trees to the right of the sidewalk are planted in a large green space. The same trees show significant difference in trunk growth and canopy density nearly 30 years later (right). Parking Surface Comparison Chart Manufacturer System Grass Pavers - Softscape (Plastic or Rubber) Unit Price (SF) Including Installation And Base Expected Lifespan Load Capability Invisible Structures www.invisiblestructures.com Grasspave2 $4.75 50-100 Yr 5,720 psi Presto Products Company www.prestogeo.com Geoblock $6.25 10-20 Yr 80,000 lbs Hastings Pavement Company www.hastingspavers.com Checkerblock $6.25 NA 5,000 psi RK Manufacturing www.rkmfg.com Grassy Pavers $5.50 10 Yr + 85,000 lbs/sf NDS Inc. www.ndspro.com Grassroad Pavers $7.25 12 Yr + 120,000 lbs/sf Grass Pavers - Hardscape (Concrete) Uni-Lock www.unilock.com Pavestone www.pavestone.com Turfstone $6.50 Grass Stone NA 20-25 Yr NA 8,500 psi NA Gravel Pavers - Softscape ( Recycled Plastic or Rubber) Invisible Structures www.invisiblestructures.com Gravelpave2 $4.75 50-100 Yr Concrete Paving $5.50 25 Yr Asphalt Paving $3.00 15 Yr 5,720 psi Martin L. Smith , ASLA POSTCONSTRUCTION CARE Tree Care after Construction Aerate or use other soil alteration methods to re-introduce oxygen and reduce compaction. Water deeply – to encourage new root development and reduce tree stress. Inspect frequently – look for visible signs of insect or disease attack. Mulch – them well but correctly! Root growth stimulators – in a year or two after they have recovered from construction stress. Fulghum Tree Care Remember, providing regular tree maintenance can help maximize the benefits and minimize costs. Benefits of Tree Protection Utilizes prevention strategies to minimize pollution by conserving mature trees Promotes clean water by eliminating erosion and run off problems using mature tree canopies Protects ecosystems and biological diversity by maintaining existing forest and habitats Reduces infrastructure costs and increases property values by working with established natural resources Creates a more sustainable community by conserving the environmental, economic and social benefits our forests provide Thank You Patti Erwin, Urban Forestry Coordinator Arkansas Forestry Commission [email protected] Resources: • Dr. Ed Gilman, Environmental Horticulture Dept., University of Florida • Casey Trees, Washington DC • Structural Soil “Olympia Style”, Joe Roush
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