Numerous depressions ranging from less than 0.8 to more than 120 ha (2 to 

 300 acres) occur throughout the interior. Shallow depressions fonri temporary 

 ponds, where standing water remains a few days to several weeks after flooding. 

 Rainfall is the primary source of water. Deeper depressions form permanent 

 lakes and ponds. Rushes, sedges, and moisture-tolerant grasses dominate. Tidal 

 flats, brackish marshes, and salt-tolerant grasslands occur in low areas subject 

 to tidal action; saltwort, shoregrass ( Monanthochloe littoralis ), and cordgrass 

 predominate. 



Review of the botanical literature describing the Gulf Coast Prairie and 

 specifically the Aransas Refuge makes it clear that major and extensive vegeta- 

 tional changes are occurring among the upland communities. Numerous authors 

 discuss the encroachment and expansion of woody vegetation, particularly live 

 oak, over areas formerly covered by tall-grass prairies (Blakey, 1947; Johnston, 

 1963; Box, 1964). Although generally still considered a grassland, the area 

 today is actually a brush-grass complex, basically a grassland with brush of 

 various densities covering almost all sites except the deepest sands. The last 

 hundred years have witnessed the greatest rate of change (Lehmann, 1965). 



The present upland terrestrial vegetation on the refuge consists primarily 

 of oak mottes, oak brushland, and grassy savannahs. Depressions of various 

 sizes support wetland complexes throughout the interior, but these sites are 

 considered to be components of the aquatic ecosystem. Live oak is unquestionably 

 the dominant species occurring in both shrub and tree form (White, 1973). Live 

 oak trees are scattered in small groves, or mottes, up to several hectares in 

 size. The brush is often very dense and may reach 3 m (10 ft) in height. This 

 species is the most aggressive local invader, and it apparently has replaced 

 much of the original savannah (Blakey, 1947; White, 1973). 



Subdominant trees and shrubs associated with live oak woodlands and brush 

 are: redbay, laurel oak, blackjack oak ( Quercus marilandica ), wax m.yrtle, 

 American beauty-berry ( Callicarpa americana ), yaupon and sparkleberry ( Vaccinium 

 arboreum ). Greenbriar (Smilax , spp. ) and mustang grape ( Vitis mustangensis ) 

 are common woody vines (White, 1973). It is clear this association is equiva- 

 lent, if not identical, to the maritime woodlands of the Southeastern Coastal 

 Plain as described by various authors (Wells and Shunk, 1931; Costing, 1954; 

 Bordeau and Costing, 1959; Johnston et al., 1974), even though specific 

 literature references to the existence of the maritime woodland in Texas are 

 rare. 



Loose sand sites between oak mottes and brush complexes, near swales, and 

 in a strip 50 to 100 m (165 to 330 ft) broad along the bay fronts are covered 

 by small patches of upland prairie. Where not too badly grazed, these prairies 

 are composed mostly of little bluestem ( Schizachyrium scoparius var. littoralis ), 

 switch grass ( Panicum virgatum ), and gulfdune paspalum ( Paspalum monoltachyum ). 

 Grazing reduces the abundance of these species, which then are replaced by a 

 great variety of grasses and forbs. Many herbaceous species rare or even lacking 

 in undisturbed stands assume importance upon disturbance. Undisturbed grass 

 lands are uncommon on the Gulf Coastal Plain (Johnston, 1955; Box, 1964). 



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