NO! A Certified Arborist should evaluate existing trees during project design to identify trees worth saving

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Albert Lambert
5 years ago
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By Carol Kwan, Certified Arborist Trees have many benefits: Clean the air Reduce the amount of

reinforcement (erosion control) Aesthetics, property values, social, economic, and other

Quantifies the dollar value of street tree benefits (environmental and aesthetic) 2007 Results

A Certified Arborist should evaluate existing trees during project design to identify trees

It had decay in large old stubs and dieback in the crown.

1 By Carol Kwan, Certified Arborist Trees have many benefits: Clean the air Reduce the amount of runoff and clean storm water Provide shade Reduce energy consumption Provide macro level soil reinforcement (erosion control) Aesthetics, property values, social, economic, and other benefits There is a monetary value to the benefits of trees i Tree i Streets (formerly STRATUM) Quantifies the dollar value of street tree benefits (environmental and aesthetic) 2007 Results for Honolulu $2.98 of benefits for every $1 spent in maintenance NO! A Certified Arborist should evaluate existing trees during project design to identify trees worth saving Approximately two thirds of the circumference of this monkeypod s trunk was dead. It had decay in large old stubs and dieback in the crown. It was not a good candidate for retaining at the site. Good Candidates Healthy Structurally sound More tolerant of construction damage Asset to the property May have historical value 1

Monkeypod trees evaluated and retained for

Poor Candidates Weedy (invasive species) Weak

structural defects In decline Wrong tree,

Chinese banyan weedy volunteer next to large

girdling roots constricting the growth of

This is a major structural defect, so the

Tree Basics Trees are alive Trees are alive

crown 95% of roots are in the top 6 12 of

2 Monkeypod trees evaluated and retained for the Wahiawa Transit Center project. Poor Candidates Weedy (invasive species) Weak or brittle wood Health problems Major structural defects In decline Wrong tree, wrong place Saving poor candidates wastes $$$ Chinese banyan weedy volunteer next to large drainage structure This young monkeypod has girdling roots constricting the growth of buttress roots at the root flare. This is a major structural defect, so the tree should be removed rather than saved. Tree Basics Trees are alive Trees are alive Roots extend 2 3 times the diameter of the crown 95% of roots are in the top 6 12 of soil Roots need oxygen to function Buttress roots near the trunk provide major structural support 2

Tree Basics continued: Trees are large, heavy structures full of water The major

compartmentalize varies by species Tree Protection/Preservation Plans Identify/fence

buildings and infrastructure, bad for trees/roots) Provide clearance for equipment

don t rip roots with equipment Limit it root pruning to one side of a tree Provide

The total water uptake needs to be maintained for the tree Temporary irrigation is

A lot more water is needed After hand trenching at the construction limits, the

3 Tree Basics continued: Trees are large, heavy structures full of water The major circulatory system is just under the bark Trees don t heal (can t grow cells in the same location). Injured areas die and are compartmentalized (walled off) The ability to compartmentalize varies by species Tree Protection/Preservation Plans Identify/fence off critical root zones Keep compaction away from critical root zone (good for buildings and infrastructure, bad for trees/roots) Provide clearance for equipment Prune branches to raise crown prior to construction Root prune prior to construction don t rip roots with equipment Limit it root pruning to one side of a tree Provide temporary irrigation. Cutting one root can remove as much as 25% of the root zone. The total water uptake needs to be maintained for the tree Temporary irrigation is not the same as dust control. A lot more water is needed After hand trenching at the construction limits, the larger woody roots are pruned. This should be done prior to erosion control measures (e.g. silt fence) Once root pruning is complete, the remaining roots within the construction zone can be removed by equipment without injuring the tree. 3

For critical roots/utilities tunnel under the roots with the

zone If fill must be done, use granular material of a uniform size so

critical root zone Prune larger woody roots before construction

grade of the adjacent slope was made steeper than 2:1 to avoid filling

Mulch was placed over the soil to minimize compaction and the branch

The following injuries can lead to tree deaths within 10 20 years

Crushed roots Removed roots Fill over roots/trunk The Contractor

removal) No temporary irrigation with major root loss (dies ikl)

4 For critical roots/utilities tunnel under the roots with the trench/piping Avoid fill on the roots, especially the critical root zone If fill must be done, use granular material of a uniform size so air can get through to the soil below Avoid excavation (cut) within critical root zone Prune larger woody roots before construction (generally 2 diameter) at construction limits prior to excavation The grade of the adjacent slope was made steeper than 2:1 to avoid filling over the critical root zone of this la amia tree. Mulch was placed over the soil to minimize compaction and the branch was wrapped to protect it from impact injury. The following injuries can lead to tree deaths within years Equipment E i t impacts to branches Equipment impacts to trunks Crushed roots Removed roots Fill over roots/trunk The Contractor violated the critical root zone for this tree, stockpiling materials up to the trunk and injuring branches. Cracked structural roots up into the trunk (requires immediate removal) No temporary irrigation with major root loss (dies ikl) quickly) Structural root loss on multiple sides of trees (risk of structural failure => immediate removal) PREVENTION IS BEST! Tree Preservation Zone violation debris and fill up to the tree s trunk 4

This utility trench was supposed to have been tunneled under the roots.

Arborist Advisory Committee nominated by the Mayor The Arborist Advisory Committee

Honolulu s Exceptional Trees website: http://www1.honolulu.gov/parks/exceptionaltrees.

Rarity Location Size Aesthetic quality Endemic status (native) Keep construction

special review process For construction within 50 of an Exceptional Tree A qualified

must present the TPP to the Arborist Advisory Committee and attend a site inspection

5 This utility trench was supposed to have been tunneled under the roots. Because the contractor violated the Tree Preservation Plan and cut critical buttress roots, the tree had to be removed. Program established by Hawaii Revised Statute Administered by each County through an Arborist Advisory Committee nominated by the Mayor The Arborist Advisory Committee reviews nominations/makes recommendations to the City Council City and County of Honolulu s Exceptional Trees website: Criteria for trees to be designated Exceptional Historic or cultural value Age Rarity Location Size Aesthetic quality Endemic status (native) Keep construction limits at least 50 away from Exceptional Trees or the project has to go through a special review process For construction within 50 of an Exceptional Tree A qualified Certified Arborist (Q.C.A.) must establish a Tree Preservation Plan (TPP) The Q.C.A. must present the TPP to the Arborist Advisory Committee and attend a site inspection with the Arborist Advisory Committee The Q.C.A. must monitor the TPP implementation during construction Adds time/$ to the design and construction schedule Exceptional Trees Military Exceptional geometry tree, Schofield Barracks. This tree is by the Schofield Barracks Warriors in Transition project, within 10 of a proposed playground. 5

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B. The purpose of the meeting shall be to establish the conditions of all existing trees upon receipt of the Project site by the Contractor. Failure t

B. The purpose of the meeting shall be to establish the conditions of all existing trees upon receipt of the Project site by the Contractor. Failure t Standard Specification SECTION 01 56 39 TREE AND PLANT PROTECTION PART 1 - GENERAL 1.1 WORK INCLUDED A. Perform all Work necessary and required to protect and maintain all trees, shrubs, groundcover and