panicun plant occurs. Lack of a seed source probably relegates it to a 

 secondary role in this area. Most of the bitter panicum commonly occurring in 

 the experimental dune vicinity probably originated from imported planting 

 materials, which came from south Padre and Mustang Islands. 



b. Vegetation Behind (Landward) Experimental Foredunes . The most 

 obvious difference between the unplanted, natural area landward of the normal 

 dune line and that of the same area behind the experimental plantings is the 

 vegetation density and cover. Because no well-defined dune existed on the 

 unplanted area. Hurricane Allen redistributed much of the sand in the random 

 patches of preexisting vegetation and sand from the backshore, spreading it 

 landward over the area of the normal dune line. Thus, much of the existing 

 vegetation was covered. The ground cover decreased from 28 percent in 1976 to 

 17 percent in 1981 (Table 9). 



Because well-developed dunes exist from experimental plantings, Hurricane 

 Allen transported sand inland only between dunes and at the breach in the 

 335-meter bitter panicum dune. Consequently, a well-developed grassland now 

 exists landward of the experimental dunes with 56 percent ground cover, up 

 from only 39 percent in 1976 (Table 9). The hurricane-deposited sand occurred 

 only locally; therefore, it covered little vegetation. The area landward of 

 the experimental dunes is relatively low in elevation and fresh rainwater 

 tends to pond there, producing vegetation with a marshy-type component in the 

 local low spots. Species, such as gulf dune paspalum, American bulrush (Sairpus 

 amerioanus) , Fimhristylis spp., largeleaf pennywort {Hydroootyle bonariensis) , 

 coast brookweed (Samolus ebraateatus) ^^ sand rosegentian (Sabatia areniaola) , 

 and longleaf flaveria (Flaveria oppositifolia) occurred commonly in these 

 lower areas (Table 10). 



Sea oats, bitter panicum, and shoredune panicum (Panicum omaTulwn) 

 invaded rapidly on this landward area following the experimental dune 

 plantings in the early 1970' s. Sea oats populations appear to have 

 stabilized, but the Vanieim species have increased substantially since 1976 

 (Table 10). Most of the Panicum appears to be bitter panicum, but the breakup 

 of clumps of the bunch-type bitter panicum made exact identification 

 difficult. Most of the plants encountered were judged to be bitter panicum. 

 Bermuda grass (Cynodon dactylon) and seashore dropseed were common in local 

 areas in 1976 and had changed little overall by 1981. Saltmeadow cordgrass 

 was common behind the 336-meter sea oats dune, but was mostly absent 

 elsewhere. Red love grass (Eragrostis oxytepis) occurred occasionally in 

 1975-76, but was quite common in 1981. Also, purple love grass (Eragrostis 

 upectablis) was occasionally encountered. Behind all the experimental dunes 

 prairie senna and Corpus Christi fleabane were abundant and had increased 

 during 1976 (Table 10) . The latter species occupied the less marshy or drier 

 sites on the lowlands behind the experimental foredunes. 



c . Vegetation in Front (Seaward) of the Experimental Foredunes . 

 Hurricane Allen denuded essentially all the beach (including the backshore) 

 back to the foredunes (Fig. 15). However, live shoots were common everywhere 

 from perennial grass roots and rhizomes, particularly of sea oats and bitter 

 panicum, adjacent to the experimental dunes. In addition, new shoots of 

 saltmeadow cordgrass were common on the formerly vegetated beach of the 

 "pedestrian only" area north of Malaquite Beach (Fig. 7). These new shoots 



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