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6
<br />
<br />Minimize the
<br />Impact o f
<br />Construction
<br />ActiVities
<br />
<br /> in addition to protecting the PP,,Z,
<br />there are other ways in which you can
<br />reduce the impact of construction
<br />activities 'on your .trees· Some of these
<br />are relatively simple; others can be
<br />extremely expensive. Carefully
<br />consider the importance of each tree to
<br />tile future appearance of the site and
<br />consult a tree-care specialist before
<br />deciding whether protective measures
<br />are worth the cost.
<br />
<br />SITE CLEARING
<br /> ~ When youremove a large ni2mber
<br />of trees, you expose the remaining
<br />plants to new-conditions. Sudden '
<br />increases irt amounts of sunlight and
<br />wind will shock many of your trees. It
<br />is not uncommon to find scorched
<br />leaves, broken branches, and uprooted
<br />tree~ ·after a site ts cleared. Although
<br />some.of these problems are tempo~
<br />rar),,.they ma), compromise tree health
<br />when coupled with additional con-"
<br />strucfion damage.: -.-
<br />"You can avoid sun and wind .
<br />stress by saving groups of trees rather
<br />
<br />Figure6, A root system bridge Will help
<br /> protect trees in the.pa, th of comtruction
<br /> vehicles. ' ·
<br />
<br />than individuals. Wht, n possible, lng concrete from the truck through
<br />remove the unwanted plants in winter conveyor pipes.
<br />after the leaves have fallen. Dormant Improper handling or disposal of
<br />plants are less susceptible to damage, materials used during construction
<br />and frozen ground helps protect roots, also can harm roots. For example,
<br />Bulldozers should not be used Ir. wood products treated with penta-
<br />remove trees near plants to be pre- chlorophenol and creosote can be
<br />served. Heavily wooded sites should deadly to tree roots; CCA-treated
<br />be gradually thinned over two to three timber (greenish color) is a better
<br />',,ears to reduce removal shock on alternative. Ask tile builder about the
<br />remaining plants. Tiffs is especially materials to be used on tile site and
<br />important in dense pine, spruce, or fir read product labels. Chemical spill
<br />forests, damage can be pre`,,ented by filling
<br /> gas tanks, cleaning paintbrushes and
<br /> tools, and repairing mechanical
<br />SOIL DAMA GE equipment ',',,ell outside tree PRZs.
<br /> Soil compaction is the single lnsist that all building debris and
<br />la'rgest killer of urban trees. Tree roots chemical wastes be hauled away for"
<br />need loose soil to grov,,, obtain ox``,- proper disposal, and not burned or
<br />.gem and absorb water and nutrients, buried on the site.
<br />Stockpiled building materials, heavy Finally, avoid changes in soil pH
<br />machinery, and excessive foot traffic (acidity). 'Increases in pH are particu- -"-'
<br />-all damage soil structure. Lacking larly dangerous to many species
<br />good soil aeration, roots suffocate and (Table 1). Alkaline clavs or limestones
<br />tree health declines. - should not be used for fill or paving, ,.
<br /> Prevent soil compaction by and concrete should be mixed on a
<br />carefully selecting storage areas and thick plastic tarp or outside the site.
<br />traffic routes (the .future driveway is a Mixing trucks should never be rinsed
<br />good choice for both) and installing out on the site.
<br />protective fences and signs. If yot~.. .
<br />can't reroute traffic, install root system , '.
<br />bridges (Figure 6) or spread Several GRADE CHANGES
<br />inches of wood chips on the soil Moving large amounts of soil
<br />within the PRZ. Heavy mixing trucks within the PRZ usually kills a tree.
<br />can be kept off tree roots by transPor.t- Except where absolutely necessary,
<br />
<br /> avoid disruptions to the natural
<br /> contour bf the site or shift them well
<br /> outside the PRZ.
<br /> 'Soil additions compact the soil
<br /> around a tree and often raise the `,,cater
<br /> table. You may be able to protect
<br /> compaction-tolerant trees (Table 1) .
<br /> from additions df six inches or less of
<br /> §oil by using a porous fill within the
<br /> PRZ. Porous fill can be mad~ by
<br /> mixing one part loam,one part coarse
<br /> sand, and one part shredded bark.
<br /> Deeper fills require.more expen-
<br /> sive measures. A retaining wall -
<br /> · beyond the PRZ ma),. protect some
<br /> trees (Figure 7~).' These wails preserve
<br /> . much of the original root system and
<br />· redirect excess water away from
<br /> sensitive plants..Your tree-care
<br /> specialist may suggest other, more
<br /> elaborate measures for protecting trees .
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