(a) Illustration of Tree Buffer/Setback Combination Options.
(1) Figure 1 illustrates the tree buffer/setback combination options for applicants.
A. The "tree" symbol illustrates the number of rows required under each option.
B. Minimum setbacks are represented by the "structure" symbol ranged along a linear scale showing distance from the urban/agricultural boundary. Setbacks apply to any structure or property line as defined.
(2) The figure does not depict screening shrubs; however, that element is required when a tree-based buffer is used and when the tree species in the first row on the agricultural side will not provide sufficient foliage cover to ground level.
(3) Where there is a mix of urban uses, the buffer design shall protect the most sensitive use among them.
(b) Tree Buffers.
(1) Three-Row Buffer. Depending on the species used, the minimum possible tree buffer width is 100 feet. A 50' setback from buffer/mitigation area is required to property line for a high sensitivity urban receptor and 50' to structures for low sensitivity receptors. The buffer area may be extended to 150 feet with no setback required. The buffer shall be composed of at least two different conifer species.
Figure 1. Illustration of Tree Buffer
Figure 2. Three-Row Tree Buffer
(2) Row Spacing and Offset. The purpose of the row-by-row offset is to mitigate the effect of individual tree mortality and to compensate for the individual differences between trees.
A. Three-Row Buffer.
i. Offset. Set off the second row by one third the spacing distance of trees (ST) in the first row; set off the third row by another third. Refer to Figure 2 for clarification.
ii. Spacing of Rows. The distance between rows will be determined using the following formula, where SR is the spacing distance between rows, D1 is the widest foliage diameter of the tree species in one row when it reaches a height of 30 feet, and D2 is the widest foliage diameter of the tree species in the next row when it reaches a height of 30 feet:
SR = 0.5(D1 + D2) + 4
(3) Tree Spacing within Rows. Tree spacing within a row is based on the greatest foliar diameter of a given tree species when it reaches a height of 30 feet. Coniferous trees vary from narrow pyramidal forms (e.g., Atlas cedar) to broad pyramidal forms (e.g., Norway spruce), so the following table contains calculation methods for each.
Table 1. Calculation of Tree Spacing within Rows for Narrow- and Broad-Diameter Trees
Narrow ST = | Broad ST = | |
single-species row | 1.25D | 1.1D |
two-species row | 0.625(D1 + D2) | 0.55(D1 + D2) |
D = Typical foliar diameter of a tree species when 30 feet tall. The diameter is measured at the widest extent of a pyramidal conifer.
ST = Tree spacing within rows; calculated as a multiple of tree diameter.
Note: When planting more than two species in a row, use the two species with the widest diameters to calculate spacing.
(4) Minimum Tree Height at Planting. Five to six feet, balled and burlapped.
(5) Permitted Tree Species.
A. Applicants may use any species of conifer trees provided they are resistant to or will not harbor agriculturally harmful insects or diseases.
B. A list of recommended species is available in Appendix I
(c) Transitions between Buffers of Different Intensity. The principal purpose of the tree buffer is to mitigate spray drift; spray height is the primary factor in determining whether a higher- or lower-intensity buffer is required. To lessen the amount of spray being carried past a transition between the two types of buffer, the applicant will extend the buffer 75 feet beyond the end of the higher-intensity buffer, as shown in Figure 4.
Figure 4. Buffer Overlapping for Transition Areas
(d) Screening Shrubs.
(1) Screening shrubs are used only in conjunction with tree buffers.
(2) If the first row of trees on the agricultural side of the tree buffer does not have foliage down to ground level, install screening shrubs to provide sufficient foliage cover to close the gap. If the first row of trees on the agricultural side of the buffer provides foliage down to ground level, then screening shrubs are not required.
(3) The mature height of the shrubs shall be 125 percent of the anticipated ground-to-foliage bare space of the average mature specimen of tree species.
(4) Permitted Screening Shrubs.
A. Applicants may use any species of screening shrubs provided they are resistant to or will not harbor agriculturally harmful insects or diseases.
B. A list of recommended species is available in the regional plan, Appendix III, available at the Village of Johnstown zoning departments.
(e) Trespass-Inhibiting Hedges and Fences.
(1) Hedges and fences may be used separately or in combination to inhibit trespass onto agricultural land.
(2) Hedge Standards.
A. Spacing and Number of Rows. One or more rows, whichever is sufficient to create an eight-foot- wide buffer at maturity.
B. Spacing within Rows. As appropriate to eliminate gaps within three years of planting.
C. Overall Height.
i. No less than three (3) gallon if being used solely as a trespass inhibitor.
ii. If doubling as screening shrubbery, the hedge needs to cover any bare space between the ground and the lowest branches of trees in the central portion. Mature height shall be 125 percent of anticipated ground-to-foliage bare space of average mature specimen of tree species being screened.
D. Permitted Trespass-Inhibiting Species. Applicants may use any species of trespass-inhibiting hedges provided they are resistant to or will not harbor agriculturally harmful insects or diseases. A list of recommended species is available in the regional plan, Appendix I, available at the Village of Johnstown zoning departments.
(3) Fence Standards.
A. Minimum fence height: six feet.
B. Fences shall be climb resistant.
C. Install gates only when necessary for maintenance of the mitigation area.
(f) Other Design Requirements.
(1) Road Placement. It is always preferable to not bisect buffers with roads due to the wind-funneling effect they create. If a road is unavoidable, it should be as narrow as possible, not straight, and should not be oriented to the prevailing wind. It should be noted that even a road with an acceptable orientation and design will permit some degree of increased spray drift to pass through the buffer area, and will also pose a greater risk of trespass
(Ord. 20-2018. Passed 6-19-18.)