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~-~.----........-- ~--- -,~---~'---- 5c\ :,iO} 6 54 P\ .,6885 Rreventing Construction Damage to Tree. Also, ~oisture stress may develop from grade changes that lower the water table or eli. vert ~a~nage patterns awa~ n'm~1 the site On the other hand excess soil moisture may develop from grade changes, as welL A nse In the .w~ter table, puddl~f ~m improper grading, or ~ increase in water flow through the area will decrease the amount of oxygen 111 me root zone an e to tree decline. Adding fill soil or cutting away excess soil alters ~e environment ~ro~d tree roots. Hauling in fi~l.reduces oxygen to the roots. Adding as little as 1 or 2 inches of heavy clay ~o~l on top of the ~~stmg grade may damag~ senslt:ve trees such ,ar:; o~s. The soil profile and soil pH are also altered. TopsoIl IS often more acIdic than excavated sU~Olls.spread ~n the surface: 1rees adapted to growing in acidic topso~l will ~ stre~sed when .for~ed to de,:elop ne~ roots 111 sOlI of a different pH and te~ure. Ability of roots to take up many ffilcronutnents IS reduced m high pH SOlIs, leading to decreased growth rate and yellowmg leaves. Construction material buried on-site also often raises soil pH. Symptoms of damage Symptoms of construction damage to trees appear over a period of several months to several years after the damage occurs. Because of the delay in development of symptoms, it is often difficult tor people to understand the relationship between the earlier injury and the current symptoms. The first symptoms to develop may be a slight V\~lting or shedding of a few leaves at the time of construction. Fall coloration often develops early and leaves drop prematurely. In later years, leaf size and shoot grO\'vth may be reduced. Twigs and branches die, and in the case of conifers, excessive needle drop occurs. General growth of the tree is slowed and resistance to diseases and insects is weakened. Diagnosing compaction or root smothering damage can be difficult because it may take five to seven years for symptoms to appear. The speed and severity of symptom development depends on the amount of damage, the species of tree and soil type. Deciding which trees to save The first step in deciding which trees to save is to accurately mark out placement of prolX'sed buildings, driveways, parking areas and utility routes. After marking these features, stand back to look over the site. A small shift in the position of the building, a change in driveway locatiof4 .or altering the proposed utility line CQuld make the difference between saving or cutting a valuable tree. After d~iding on building .placement, pri.o~tize trees for saving. Trees directly in the way of constructian; undesirable, weedy tree speCIes; trees already 111 a state of dechne; .or stmcturally hazardaus trees should be marked far removal. If in daubt consult a trained arbori:)1. horticulturist, forester or nursery person t.o determine tree condition. -, Next~ determine which trees can be saved with little .or no protection. Desirable trees located away from construction or traffic areas will survive if rea~anable care is taken. The final group of trees to e~am~ne are those that ~ay survive construction, but only if proper measures are taken. Examine ~lem 11!or~ closely to deten:mle If .one of the techniques described below will effectively minimize damage, If severe damage is likely, It \Vl11 be less expensIve to remove the tree before construction begins than afterward. Preventing damage Control traffic around trees Tree roots are not mirror images of the tree top. Roots are concentrated in the top 12 to 18 inches of soil and spread t\:I/O to hOp:/ 1m u..,,:tension ,m issouri .edul e:.;pl ore/au" i deslborti g06118S .htm Page 2