of these is largely a function of sand supply. All windblown sand avail- 

 able at a site can be trapped by these devices. Vegetation does a more 

 complete job since it stabilizes as well as traps. Sand is seldom lost 

 unless the vegetative cover is damaged or destroyed; sand is often lost 

 from fences. 



Average annual rates of sand accumulation vary from less than 3 cubic 

 meters per front meter on a shelly beach to 10 cubic meters per front 

 meter on a wide sandy beach, for fences and American beachgrass plantings 

 in North Carolina (Savage and Woodhouse, 1968). European beachgrass 

 caught an average of 13.7 cubic meters per front meter a year for a 30- 

 year period on the Clatsop Plains of Oregon (Meyer and Chester, 1977) . 

 The rate was probably higher than this the first few years. None of 

 these approach the rate of 40 cubic meters per front meter in the first 

 15 months recorded on a 30-meter square of American beachgrass on an 

 exposed site which received sand from all sides (Savage and Woodhouse, 

 1968]. Thus, the trapping capacity of vegetative plantings usually 

 greatly exceeds the sand supply. The capacity of a single 1.2-meter- 

 high sand fence is about 5 to 7 cubic meters per front meter. 



Ultimate dune height and rate of growth varies widely. Ocracoke 

 Island dunes, initiated with American beachgrass, increased in height by 

 about 18 centimeters per year in a 10-year period. However, upward dune 

 growth slowed drastically and almost ceased during the last half of the 

 period (Woodhouse, Seneca, and Broome, 1976); most of the growth became 

 lateral, toward the sea. Increase in height of a sea oats dune on Padre 

 Island averaged 60 centimeters per year and a similar bitter panicum dune 

 increased 46 centimeters per year over a 5-year period (Dahl, et al., 

 1975). The Clatsop Plains dune crest increased an average of 27 centi- 

 meters per year over a 30-year period. These differences reflect varia- 

 tions due to climate and sand supply as well as species characteristics. 

 Sea oats, bitter panicum, and European beachgrass build high steep dunes 

 when sand is plentiful because they expand laterally at a slow rate. 

 American beachgrass builds broader more gently sloping dunes with lower 

 crests since it can expand toward the sand source at rates as high as 3 

 or 4 meters per year. 



5. Costs. 



Sand fence, when bought in quantity, costs about $1.25 to $1.50 per 



meter (free on board) factory. Cost of posts and braces varies widely 



with material and locality but should be less than $0.50 per meter of 

 fence. The installation of standard 1.2-meter slat-type sand fence with 



all materials on site requires 1 man-hour for 9 to 14 meters. Fabric 



fences are usually competitive in price, but have a slightly higher 

 labor cost. 



Planting costs vary with species, availability of planting stock, 

 planting method, and nature of site. American beachgrass is available 

 in quantity on the Atlantic coast at about $15 to $20 per thousand stems. 

 Planting rate is about 400 to 600 hills per man-hour by machine and 130 

 to 200 hills per man-hour by hand. 



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