Village Cut Down Trees Forest Screen Sparse Want to Fill in Again
Douglas F. Welsh, Professor and Extension Horticulturist
Everett E. Janne, Extension Mural Horticulturist (deceased)
Class changes are ofttimes necessary while edifice sites are being prepared for construction. Often the building site has been called because of the presence of mature trees. Notwithstanding, any change in grade around existing trees tin can have a pregnant affect on their survival and future growth. Unless corrective steps are taken immediately, lowering the grade exposes the existing root system to the air and reduces the supply of nutrients and moisture available to the roots.
Raising the class or soil level over existing roots tin have an fifty-fifty greater issue on the future growth and survival of existing copse. When soil or any blazon of fill is placed over the existing root system, it causes a reduction in the oxygen supply to the tree roots and slows downward the rate of gas commutation between the roots and the air in the soil pore infinite.
Both oxygen and water are essential to the growth, development and nutrient uptake by the roots. Many of the soil organisms also utilize the water and oxygen in their normal growth processes. Lack of oxygen in the soil may effect in accumulation of noxious gases and chemicals detrimental to skillful growth. When this occurs, the feeder roots neglect to develop, the root system and the above-footing portion of the tree begin to turn down. Many factors (including tree species, depth and blazon of fill, drainage, soil structure below the fill and the general vigor of the existing tree) have a determining influence upon the time information technology takes for the above-basis symptoms to appear. Thus, it might take anywhere from several months to every bit much as 3 to 5 years earlier tree death would occur.
Determining Feasibility of Preventing Injury
When the grade effectually an established tree is being raised, careful consideration should exist given to methods of preventing injury to the tree before the make full is made rather than attempting to take corrective measures afterwards the damage has been washed. While the initial cost may be loftier, preventing damage is always cheaper and more effective than attempting to correct the state of affairs afterwards the damage has been done.
Several important factors should exist considered in attempting to determine whether the toll of saving the tree is worth the endeavor and expense of making the installations necessary to prevent or reduce extent of injury.
Density of Tree Population. Where copse are deficient, any attempt to save i or two sound trees is usually worthwhile. If there are numerous trees on the holding, the holding owner may not experience that the cost to relieve 1 or two in the immediate construction site is justified.
Species and Multifariousness. Some of the fast-growing, short-lived copse may non exist worth the price of trying to save them. Simply a good healthy tree that is mature or adapted to the area, with a long life expectancy, is hard to replace. For such copse, the expense of providing the necessary protection tin frequently be justified.
Age and Vigor of Existing Trees. The status of the tree is an important gene in determining its worth. If it has a large cavity, has been severely damaged by lightning or tempest, or has lived out a normal life span, it is difficult to justify the expense and labor necessary to relieve the trees. This is especially true if there is danger of losing it to other causes. But a young, vigorous tree, if attractive and well placed, would be valuable plenty to save.
Proper Installation of Deep Make full Effectually Existing Trees.
All vegetation should exist removed, including sod and underbrush beneath the branch spread of the tree. Organic matter, equally it decomposes beneath a soil fill, can create noxious gases detrimental to the tree roots.
The peak 3 to 6 inches of the soil surface should be cultivated or cleaved upwardly advisedly so as to disturb the to the lowest degree possible amount of roots. This handling allows better contact with the fill soil and prevents a precipitous line of demarcation betwixt the existing soil surface and the fill.
As a retainer around the body, an open-articulation wall of shell, rock, masonry or brick in a circle around the tree trunk should be constructed with at to the lowest degree 1 to two feet between the body and the wall. The wall should be as high as the top of the new grade. The completed opening is commonly referred to as a tree well.
An aeration system can be constructed using four-inch perforated plastic pipage bundled in v to 6 horizontal lines radiating from the tree well similar spokes in a wheel to a point beyond the co-operative spread. The radial line should be installed then they slope from the tree trunk, thus allowing excess moisture to drain abroad. The outer ends of the radiating organization should be continued with a circle of perforated plastic pipage every bit shown in Figure one.
To provide vents, 4 or half dozen-inch plastic pipe or bong tile can be placed upright over the junction of the radial lines with the circle. These upright tiles should extend to the surface of the planned grade level and can be held in place with coarse gravel or stone. The low end of the aeration organisation should be extended to a curb, storm drain or sump to carry off backlog moisture.
The exposed soil and the aeration system should be covered with rock or coarse gravel to a depth of 6 to 18 inches, depending on the amount of fill, followed by a covering layer of gravel. To prevent soil from filtering into the gravel and rock, a thin layer of straw, woven plastic or other porous material can exist placed over the gravel and so filled in with good summit soil to the desired or finished grade.
Placing sufficient coarse gravel in the tree well to encompass the ends of the lines opening into the well volition discourage rodents from eating the system. Coarse gravel can also be placed in the upright bell tile or plastic pipe and covered with a screen of grill to prevent rodents from making nests in the tile arrangement. A vertical section of the completed make full can be seen in Figure 2.
A tree well tin be left open. Notwithstanding, for safety purposes, it may be covered with a wooden deck or a metal grill. The well tin also exist filled with a mixture of coarse sand and charcoal (50% each, by volume) to inside several inches of the top. This mixture can be covered with pea gravel, decorative bark or other attractive material to allow adept air movement into the tile system.
An alternate method can be used where not over 24 inches of fill volition be used, and where internal soil drainage is good. In this approach, no perforated pipage is used, merely gravel. Again, all sod and underbrush must be removed, the soil surface broken upwards above the roots, and any needed fertilizer applied. Starting at the outer extremities of the branches, apply from 3 to 6 inches of coarse gravel or crushed stone. The depth towards the trunk of the tree should be increased gradually until it is 8 to 12 inches or deeper within 2 feet of the body. The gravel can reach the surface of the fill in the area extending two feet around the trunk of the tree (run across Figure iii). The gravel can be covered with a thin layer of straw, woven plastic or other porous material to keep soil from filtering into the coarse gravel and sealing the air spaces. Some good height soil should be spread over the area to the desired depth (see Figure 3).
To Lower the Existing Grade
Less damage is probable to occur to a tree when the grade is lowered in the vicinity of the root zone unless great amounts of roots are exposed or removed. The removal of 1 to 2 inches of soil will not normally affect the growth of the tree, particularly if steps are taken to prevent drought impairment resulting from loss of roots. Terraces or retaining walls (see Figure iv) 
If possible, a mulch of any blazon should exist spread over the exposed expanse to help aid in preventing soil erosion, in cut downwardly on moisture loss, and in keeping soil temperatures more than moderate. Provisions should also be fabricated for adequate irrigation in the event of a prolonged drought.
Cosmetic Steps to Have After a Fill Was Made
If a fill up has been in place long enough for visual symptoms of tree deterioration to occur, picayune can be done to save the tree. In cases where the make full has been fabricated recently or where no serious damage has occurred, some corrective activeness can be taken.
If the increase is less than 12 inches, it is possible to remove soil around the tree trunk downwardly to the original soil level for a radius of 2 feet beyond the trunk. A dry well should be installed around the trunk to hold the fill soil in identify. Starting well-nigh 2 feet out from the dry well, holes should exist drilled or dug every two feet below the branch spread. A 6-inch plastic pipe should be inserted then filled with coarse gravel to allow free air and gas substitution in the root zone. This will normally suffice for a shallow fill up.
Where deeper fills have been made, it will be necessary to install a pipe and gravel aeration system equally described previously. The soil around the tree trunk should be excavated to the original grade with radial trenches extending to the outer limits of the branches. A well should be constructed effectually the torso to go on back the soil. The radical trenches should be joined with a circular trench located at the dip line of the branches. The depth of the trenches should be dug to the original form line and the system should gradient sufficiently to provide good drainage away from the tree trunk. In order to carry off surplus moisture, it may be necessary to extend the radial line on the downwardly hill side to a natural drain or into a sump or cistern. A 4-inch perforated plastic pipe aeration system should be installed and covered with gravel earlier replacing the soil back to the new grade line. The installation volition be identical to that described previously, except the installation volition have been made after the fill was installed.
Because there can be no assurance that a tree volition recover from the damage already done, careful consideration must exist given to the value of the tree in the mural earlier expensive cosmetic measures are undertaken. The tree would have to be extremely attractive, valuable or accept meaning historical value to justify the expense of these corrective measures since success is not bodacious.
The preventive measures outlined in this publication will in almost cases insure the connected life and usefulness of the tree (Figure 6). The decision the property owner must brand after evaluating the aesthetic or landscape value of the tree and the cost of installation is whether the tree is worth the cost and effort involved.
The information given herein is for educational purposes only. Reference to commercial products or merchandise names is fabricated with the understanding that no discrimination is intended and no endorsement past the Texas AgriLife Extension Service is implied.
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, faith, age, or national origin.
Publication Revised November 2008
Source: https://aggie-horticulture.tamu.edu/earthkind/landscape/protecting-trees/
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