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SPECIFICATION - 391 - 2 <br />4 866.60 7.09 4 1733.19 5.01 <br />3 1540.62 5.32 3 3081.23 3.76 <br /> <br />75% Canop y/Crown Closure 100% Can opy/Crown Closure <br />Avg. Crown Width-ft. Trees-shrubs/Ac Spacing- <br />ft. Avg. Crown Width-ft. Trees-shrubs/Ac Spacing- <br />ft <br /> <br />25 <br />66.56 <br />25.58 <br />25 <br />88.74 . <br />22.16 <br />20 103.99 20.47 20 138.66 17.72 <br />18 128.39 18.42 18 171.18 15.95 <br />15 184.88 15.35 15 246.50 13.29 <br />12 288.87 12.28 12 385.15 10.63 <br />10 415.98 10.23 10 554.62 8.86 <br />8 649.96 8.19 8 866.60 7.09 <br />6 1155.49 6.14 6 1540.62 5.32 <br />5 1663.91 5.12 5 2218.49 4.43 <br />4 2599.85 4.09 4 3466.38 3.54 <br />3 4621.96 3.07 3 6162.46 2.66 <br />Notes: Calculations are based on crown width at 20 years of age. Mortality and crown overlap were not included in <br />calculations. Use local knowledge/experience and adjust trees/acre & spacing accordingly. Trees/acre and spacing <br />are given to the nearest 1/100th to decrease error when extrapolating data to larger than one acre plots. For spacing <br />where rows consist of different species, the planner should add the two spacings and divide by two to find the between <br />row spacing. <br />Approximate crown widths at 20 years in feet for common riparian species <br />Plains cottonwood >25 Birch 10 <br />Narrowleaf cottonwood >25 Serviceberry 10 <br />Fremont cottonwood >25 Chokecherry 10 <br />Boxelder 20 Dogwood 7 <br />Aspen 15 Willows-shrub type 7 <br />Spruce 15 Shrubby cinquefoil 5 <br />Peachleaf willow 15 Currant 5 <br />Hawthorn 15 Rose 5 <br />Rocky Mtn. maple 10 Snowberry 5 <br />Mountain ash 10 Buffaloberry 5 <br />Alder 10 New Mexico privet 5 <br />NATURAL REGENERATION <br />Where natural regeneration is expected to occur, an average canopy/crown closure of 25% is required <br />in Zone 1 after 3 years. <br />SPECIES SELECTION <br />Dominant vegetation will consist of existing, naturally regenerated, or planted trees and shrubs suited <br />to the site and the intended purpose, Selection of locally native trees and shrubs will be a priority <br />when feasible. Species selected should normally be found in the part of the state where the buffer will <br />be planted (e.g. aspen should not be planted in Yuma County). Plantings will consist of two or more <br />species with different plant types/heights. Plants must be suited to the seasonal variation of soil <br />moisture status of individual planting sites (see Figure 1). <br />NRCS, CO <br />AUGUST, 2006