CMG GardenNotes #652 Tree Preservation During Construction

Transcription

1 CMG GardenNtes #652 Tree Preservatin During Cnstructin Outline: Guiding principles f tree preservatin, page 1 Develpment sequence, page 3 Tree reprt, page 4 Assessing tree tlerance, page 6 Tree Prtectin Zne, page 8 Symptms f cnstructin damage, page 11 In tree preservatin, take steps t prevent cnstructin damage, as little can be dne t crrect it! This CMG GardenNtes was written as an verview f tree preservatin issues in a cnstructin site. Fr additinal infrmatin refer t: Trees and Develpment, A technical Guide t Preservatin f Trees During Landscape Develpment by Nelda P Matheny and James R Clark. Internatinal Sciety f Arbriculture ISBN: Up By Rts: Healthy Sils and Tree in the Build Envirnment by James Urban. Internatinal Sciety f Arbriculture ISBN: Guiding Principles f Tree Preservatin 1. Gals in tree preservatin include bth cnstructin AND tree preservatin. Bth gals have t be valued. Bth sides have t make cmprmises. Plarizatins f attitudes include 1) that it is cheaper, easier and faster t remve all trees at the start and 2) that all trees need t be saved. Fr tree preservatin, cmprise must be fund in the middle. The gal is nt t preserve trees just until ccupancy ccurs, but rather fr twenty plus years

2 2. Preservatin requires cmmitment f all parties, as a team effrt. Owners Engineers Architects and landscape architects Grading and demlitin crews Cnstructin and landscape crews Gvernment agencies Arbrists, wh s rle includes Technical resurces and tree knwledge Familiar with lcal regulatins and regulatry staff Familiar with lcal grwing cnditins 3. Tree preservatin cannt wait until cnstructin r afterwards. Tree preservatin takes place in the planning phase. Cnstructin crews then fllw the plans. 4. All trees cannt and shuld nt be preserved. Trees require that space be prtected fr their rts. Trees in pr health simply will nt tlerate cnstructin stress. Trees with pr structure have limited value. 5. Tree preservatin patterns must respect patterns f tree grwth. All players in design and cnstructin must respect the Tree Prtectin Zne, TPZ. Fr additinal infrmatin n rting spread refer t CMG Garden Ntes #113, Diagnsing Rt and Sil Disrders f Landscape Trees. Trees have a rt plate system, shallw and wide spreading. 6. Tree preservatin requires abve and belw grund space. Inside TPZ there is NO grading, trenching, parking, stck piling f building materials r dumping f waste prducts

3 7. Preservatin fcuses n preventing injury t trees, as little can be dne t crrect injury. 8. Cnstructin impacts t trees are cumulative. Small impacts add tgether fr stress and tree decline. 9. Tree preservatin requires accurate site infrmatin. Lcatin f buildings, utilities and hardscape features Lcatin f trees Species identificatin and tlerances t cnstructin stress Evaluatin f tree health and ptential fr preservatin 10. Arbrists and design/cnstructin prfessinals must cmmunicate. Talk in technical terms. Bth sides must be willing t cmprmise. 11. Cmmunity attitudes and practices must supprt bth tree preservatin and develpment. A cmprmise must be fund between the plarizatins f 1) aggressive tree preservatin rdinances and practices that prhibit cnstructin and 2) ignring tree preservatin in favr f cnstructin. The same standards shuld apply t bth private and public sectr develpment. Develpment Sequence 1. Site design including tree reprt Requires cmmunicatin and cmprmise between all parties. This is the mst imprtant step in tree preservatin. 2. Review and apprval by public agency Cnditins f apprval Bnding: appraised value f trees preserved Permits 652-3

4 3. Site wrk 1. Tree wrk Tree wrk needs t be cmpleted befre ther activities start. Due t cnstructin schedule, the time frame fr tree wrk may be very shrt. Tree prtectin needs t be in place during site wrk. 2. Demlitin and clearing 3. Grading 4. Utilities and rads 4. Cnstructin and landscaping Tree prtectin needs t be in place during site wrk. Implement tree maintenance during cnstructin plan. Hw/wh will the tree be prtected during cnstructin? Hw/wh will the tree be watered and cared fr during cnstructin? 5. Occupancy Implement pst-cnstructin maintenance plan. In tree preservatin, it shuld be expected that the tree lives fr twenty plus years, nt just until site ccupancy. Tree Reprt Step A Inventry and Evaluatin Identify trees suitable fr preservatin. Species Size Health and vigr Structural integrity Age Yung trees are mre tlerant f cnstructin stress. Species tlerance t cnstructin stress Maintenance requirements Trees suitability t new use Grup r specimen trees Trees are ften easier t preserve in a gruping rather than specimen trees

5 Crwn class Dminant trees make the best ptins fr preservatin. C-dminant trees are best preserved in grupings. Intermediate trees make a pr chice fr preservatin. Subrdinate trees make a pr chice fr preservatin due t inferir structure and sudden expsure. Step B Assess ptential impacts by calculating the Tree Prtectin Znes fr each tree. Trees under stress and/r decline are less tlerant f cnstructin related stress and d nt merit preservatin. Step C Mdify plan t accmmdate TPZ and building plans Step D Identify tree wrk Wrk t be dne by arbrist nt cnstructin wrkers. There may be limitatins n time f year fr wrk t be dne. There may have shrt time frame t cmplete wrk befre cnstructin begins

6 Step E Outline Tree Maintenance During Cnstructin Plan Wh and hw will trees be prtected during cnstructin? Wh and hw will the tree be watered and cared fr during cnstructin? Wh and hw will the tree prtectin plan be cmmunicated t all wrkers? Wh and hw will tree prtectin be mnitred during cnstructin? What penalties will be in place fr individuals and cmpanies wh vilate the tree prtectin plan? Step F Outline Pst-Cnstructin Maintenance Plan What will be dne and wh is respnsible? Sil management Pruning: Cleaning General care (watering, pest management) Assessing Tree Tlerance Species Fr cmparisn, classify species as gd, mderate r pr tlerance. There is n cmprehensive list f species tlerances. Ask experts abut their experience with specific species. Age and lngevity Fr cmparisn, classify as gd, mderate r pr tlerance. Yung trees typically have gd tlerance. Medium age trees typically have mderate tlerance. Over-mature and declining trees have pr tlerance and d nt merit preservatin. Health and vigr Trees in pr health will nt survive cnstructin related stress. Actual crwn and rting area may nt be unifrmly distributed. Structural stability Preservatin effrts are nt warranted n structurally unsund trees

7 Cuts and fills Fills are mre tlerance n flding tlerant species Cuts mre tlerance n drught tlerant species Remving sil inside TPZ On rt severance tlerant species, may disturb up t 25% f TPZ area (nt diameter). On rt severance sensitive species, allw extra space beynd TPZ. Rt Severance Tlerance Tlerant Intermediate Sensitive Up t 25% f TPZ area TPZ area Allw extra space in TPZ Ash: green, white, black Birch: paper & yellw Beech Aspen: quaking & big-tth Buckeye: Ohi Butternut Birch: river Catalpa Irnwd Bxelder Cherry: black Oak: white, nrthern Cttnwd: eastern Kentucky cffee pin and black Fir: balsam & white Hawthrn Walnut: black Hackberry Hickry: Bitternut Hneylcust Maple: sugar Lcust: black Spruce: Clrad blue Maple: silver & red Oak: bur & bi-clr Mt. Ash Pine: white, jack, & red Spruce: black, white Willw Adding sil inside TPZ If a cmpactin/flding tlerant species, may successfully add up t 6 prus fill. If a cmpactin-flding sensitive species, d NOT change grade, and TPZ (as calculated with diameter methd) may be t small

8 Rt Cvering Tlerance Tlerant Intermediate Sensitive Add up t 6 prus sil TPZ area N change in TPZ Ash: blue & green Ash: white Aspen: quaking & big-tth Cedar: nrthern white Buckeye: Ohi Basswd Birch: river Butternut Beech: blue Bxelder Cherry: black Birch: paper & yellw Fir: balsam Kentucky Cffee Cedar: eastern red Catalpa Elm: American & slippery Fir: white Cttnwd: eastern Hackberry Irnwd Maple: silver & red Hawthrn Lcust: black Spruce: Clrad blue & black Hickry: bitternut Maple: sugar Tamarack Hneylcust Oak: red, white, black, & Oak: bi-clr Mt Ash nrthern pin Willw: black Spruce: white Pine: white, jack, red, & sctch Oak: bur Plum: wild Walnut: black Changes in sil hydrlgy (sil water) Ability t recver frm stress factrs Insects and diseases Irrigatin changes Tree Prtectin Zne, TPZ Trunk Diameter Methd The trunk diameter is prbably the best methd fr general use n landscape trees. Size f the TPZ is based n the diameter f the trunk, increasing as the tree ages and becme less tlerant f stress factrs. It may be calculated by measuring the trunk circumference r diameter at DSH (diameter at standard height, 4.5 feet). Fr trees with a brad canpy in an pen lawn, it is apprximately 40% larger in area than the dripline methd

9 Trunk Diameter Methd by Circumference TPZ radius = 1 feet per 2 inches f trunk circumference 1. Measure the tree s circumference at DSH (4.5 feet) in inches. 2. Divide the number f inches by This is the radius, in feet, f the TPZ. Fr example 1. Circumference = 24 inches / 2 = TPZ radius = 12 feet Trunk Diameter Methd by Diameter TPZ radius = 1.5 feet per inch f trunk diameter at DSH 1. Measure the tree s diameter at DSH (4.5 feet) in inches. 2. Multiply the diameter (in inches) by This is the radius, in feet, f the TPZ Fr example 1. Diameter = 8 inches 2. 8 x 1.5 = TPZ radius = 12 feet Stress Tlerance and Age Methd Area f the TPZ The area f the TPZ can be calculated by the frmula: [TPZ radius] 2 x π Fr example - 12 ft radius: 12 feet X 12 feet X 3.14 = 452 square feet This methd is used in a cnstructin site when cmprmise must be made t minimize the TPZ, allwing fr cnstructin activities. 1. Evaluate species tlerance t cnstructin stress (gd, mderate, pr) Transplant respnse Drught respnse Rting pruning respnse Cmpartmentalizatin (decay respnse) Native range tlerance t stress utside native ecsystem 2. Identify tree age Yung = < ¼ life expectancy Mature = ¼ - ¾ life expectancy Over-mature = > ¾ life expectancy Older trees are less tlerant f stress and require larger TPZ 652-9

10 3. Frm the table, calculate minimum TPZ radius and area Radius f TPZ* Stress Tlerance Tree Age Feet/ inch trunk diameter Gd Yung 0.5 Mature 0.75 Over-mature 1.0 Mderate Yung 0.75 Mature 1.0 Over-mature 1.25 Pr Yung 1.0 Mature 1.25 Over-mature 1.5 Additinal space may be needed n cmpacted, clayey sils. TPZ mdificatins Methds abve are based n trees in pen area with unlimited rting space. Additinal space may be needed fr shallw rted trees, like spruce and n cmpacted clayey sils. If lw branches will interfere with wrk, extend the TPZ t include all the dripline area. Trees in grupings 1. Calculate and plt the TPZ fr each tree 2. Plt uter edge f tree grup as the TPZ fr the gruping Multiple trunk trees 1. Calculate the trunk area fr each trunk at DSH (4.5 feet). 2. Add the areas tgether. 3. Calculate the diameter f a tree that wuld have this size area in a single trunk. Area = Radius 2 x 3.14 Radius = area / Use this as the trunk size t estimate the TPZ

11 T accmmdate site needs, the TPZ area may be Offset slightly Nt necessarily rund Sites with urban hardscape restricting rt spread Methds, as described abve, will need adjustments. Need t actually check fr rt lcatin. Backhe (A gd peratr knws when he hits rts and will stp befre cutting them.) Hand digging Air spade New sidewalks and parking areas are generally OK if they say inside the ftprint f the ld area withut invading the rting area. New buildings are generally OK if they say stay inside the ftprint f the ld building withut invading the rting area. Tree Stability Fr wind stability, d nt invade the rt plate. General frmula: radius f rt plate is 3-6 times DSH (trunk diameter at standard height, 4.5 feet) Bartlett Tree Lab Mdel: radius f rt plate is 5 times DSH n ne side AND 3 times DSH n ther three sides Mattheck Mdel Fr example, a 10 inch trunk radius needs a rt plate/trunk radius cefficient f 9. This wuld be 90 rt plate radius (90 /10 = 9)

12 Symptms f Cnstructin Damage Symptms f cnstructin damage include generic symptms f stress and decline. Trees generally decline due t rt decline and death. Reduced canpy grwth Cmpare hw annual grwth changes frm year t year. Dieback n upper canpy Dieback f upper canpy n side related t rt damage Small, prly clred leaves Adventitius spruting alng trunk r lwer scaffld branches Heavy seed set Mechanical injury t trunk and limbs New Edge damage Fliage and bark damage due t increased expsure t sun and wind. Bttm line: Take steps t prevent cnstructin damage, as little can be dne t crrect it. Authr: David Whiting, Extensin Cnsumer Hrticulture Specialist (retired), Department f Hrticulture & LA, Clrad State University Extensin. Clrad Master Gardener GardenNtes are available n-line at Clrad Master Gardener training is made pssible, in part, by a grant frm the Clrad Garden Shw, Inc. Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Extensin prgrams are available t all withut discriminatin. Cpyright Clrad State University Extensin. All Rights Reserved. CMG GardenNtes may be reprduced, withut change r additins, fr nn-prfit educatinal use. Octber