THE VEGETATION OF SHACKLEFORD BANK 21 



SOIL-BUILDING PLANTS 



The most imiDortant are Spartina glabra, Salicornia amhigua, and 

 Borrichia frutescens. These are plants of the salt-marsh, and live only 

 in situations where the soil is flooded at high tide, and where the water 

 is comparatively quiet. They are an .important factor in the formation 

 of the numerous flat, marshy islands lying in Bogue Sound and around 

 the mouth of JSTewport River. At first, sandy flats, quite hare of vege- 

 tation, are formed by the currents due to wind and tide. Spartina may 

 gain a precarious foothold on the loose sand. It then sends its strong, 

 thick rhizomes here and there, binding the sand on which it grows, add- 

 ing humus, collecting and holding silt brought down by the rivers. In 

 such situations the grass is stunted and sparse, but by thrusting a spade 

 into the sand one sees that the substratum is closely occupied by the long 

 heavy branching rhizomes long before the conditions are sufficiently 

 favorable for the aerial part of the plant to send up its flowering stalks 

 or even to produce very vigorous foliage. At this stage Salicornia am- 

 higua may also gain a foothold and aid in reclaiming the sandy wastes. 

 The building up is accomplished partly by the plants catching and 

 holding the sand and silt brought to them by the currents and partly 

 by the actual addition of dead and rotted plant substance. After these 

 forces have been at work for some time the land may be raised nearly or 

 quite out of reach of high tides, and invaders begin to appear in the 

 highest ground and help build it up further. The common invaders 

 in such situations are Borrichia frutescens, Limonium carolinianum, 

 Solidago sempervirens, Strophosty'les umhellata, Iva oraria, and Spartina 

 patens. 



All stages of this island-formation can be observed near the Fisheries 

 Laboratory. On Shark Shoal^ south of the Laboratory, the Spartina 

 has. just been established. To the north are broad flats of marsh with 

 Spartina, Salicornia, and Borrichia. Where the currents of the water 

 have aided in building up the land the other species mentioned above 

 are to be seen. The town marsh is in a still later stage of development; 

 woody species such as Myrica cerifera, and various grasses and herbs, 

 have appeared. 



Changes in the small islands of the sound are not all progressive. 

 When the direction of the tidal currents is changed for any reason, the 

 result may be the denudation of land already built up. Such denuda- 

 tion has occurred in a striking Avay on Bird Shoal, just south of the 

 town of Beaufort. This island was, twenty years or so ago, of an eleva- 

 tion of 15 or 20 feet, and covered with a vigorous growth of j^lants, 



^Spartina has also been planted on Shark Shoal. 



