d. Planting on Fence-Constructed Dunes. Fabric and wooden picket sand fencing has 

 been used to build foredune barriers and temporarily halt free-drifting sand (Savage and 

 Woodhouse, 1968; Gage, 1970). Sand blown inland from the beach is trapped by one or 

 several parallel rows of 4-foot-high fencing, until a dune has built to nearly the fence top , at 

 which point the dune grows no higher. Using different configurations of sand fencing, the 

 U.S. Army Engineer District, Galveston, conducted experiments concurrently with the 

 vegetation-grown dunes on south Padre. 



Practical problems of fence-constructed dunes are: (a) there is a limit to the dune height 

 a single tier of fence can build, and more height is achieved only by adding tiers; (b) fence 

 material deteriorates in time and the barren dune is only temporary unless periodically 

 maintained; and (c) the sand surface is unstable and shifting winds may change the dune 

 configuration. 



These problems would be greatly reduced if dune-building grasses were planted after the 

 sand fences fill with sand and before the dunes begin to deteriorate. The sand would then 

 stabilize and allow the dune to continue growth without maintenance. 



Methods of establishing vegetation were tested on about 2,000 linear feet of barren 

 fence-built dunes, from 50 to 90 feet wide, in 1972-73 on south Padre. Problems of dune 

 stabilization were different from the establishment of plants on the original backshore 

 elevation because: (a) soil salinity on the dunes was low and probably had little effect on 

 survival; (b) moisture was also low, and the addition of beach-blown dry sand plus rapid 

 drying of the surface made supplemental irrigation necessary; and (c) instability of the 

 substrate and rapid drying and shifting of sands, even during periods of wet weather, made a 

 sand-stabilizing mulch essential. A major source of transplant mortality in 1973 was burial 

 by drifting sand after spring planting, when strong, predominantly onshore winds 

 transported a large volume of sand across the foreslope and deposited several feet of sand on 

 the backslope. Plants survived better and more uniformly on the foreslope. In 1972, 

 however, burial was not a problem. 



With irrigation and mulch-netting, a uniform vegetative cover on fence-built dunes within 

 1 year after planting is possible (Fig. 35). However, the cost of fencing, irrigation, mulching, 

 and the irregular survival from sand burial, make dune establishment by planting on the 

 original beach a more attractive alternative. A benefit of establishing a dune by fencing is 

 that sand accumulation and dune growth begin as soon as fences are erected, and some 

 protection is achieved quickly. 



e. Planting on Deteriorating Foredunes. In March 1974, with the cooperation of 

 personnel from the national seashore, an effort was made to halt the wind erosion of a large 

 and scenic foredune on north Padre. A foot trail to the crest allowed prevailing winds to 

 scour out a large part of the dune face; without intervention the dune would be destroyed. 

 After transplanting bitter panicum on 18-inch centers and stabilizing with mulch-netting, an 

 excellent vegetative cover was reestablished, and erosion was halted (Fig. 36). Irrigation was 



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