this zone may not be needed. Giant reed did readily establish, vegeta- 
tively reproduce, and produce seed. Thus, if needed, it could be 
utilized for stabilization in this zone. 
In the middle zone, smooth cordgrass, gulf cordgrass, black man- 
grove, and saltgrass had good survival rates (Table 20). Smooth cordgrass 
appeared to be the best plant material for this zone, based on survival 
and vegetative reproduction rate. It appears to provide a rapid cover 
for erosion control. Black mangrove shows promise of providing long- 
term cover, based on survival, and could provide long-term protection 
with growth. Although the survival rates for saltgrass in the present 
plantings were low, it may be that by utilizing sod blocks instead of 
single rhizomes, this species would provide good erosion protection in 
this zone. Thus, in the middle zone, combination plantings of smooth 
cordgrass, black mangrove, saltgrass, and gulf cordgrass will provide 
for both rapid and short-term as well as long-term protection. 
In the lower zone, black mangrove and smooth cordgrass should 
be planted in combination (Table 20). Smooth cordgrass would provide 
protection from erosion while black mangrove would provide a barrier 
against wave action. 
4. Other Studies. 
During this initial phase, other studies have been initiated in an 
attempt to gain information that would be of value in stabilization of 
eroding clay shorelines along the upper Texas gulf coast. 
a. Block V. This study block consisted of a short section of 
shoreline that was mechanically sloped. After sloping, the block was 
utilized for a planting site. 
Soil salinity was lowest in the upper zone, and within this zone 
decreased with depth (Table 21). There was very little difference in 
soil salinity between the middle and lower zones. In the middle zone 
the minimum (9,651 ppm) was in the surface 2 inches of soil while the 
maximum was in the 2- to 4-inch layer. In contrast, in the upper zone 
soil salinity increased with depth to a maximum of over 16,000 ppm in 
the 4- to 6-inch layer. 
Soil pH varied only slightly within this block (Table 22). All 
readings, regardless of depth or zone, were near neutral. 
Sodium was the most abundant cation in this block (Table 23). 
In the upper zone, Na concentration was highest in the surface 2 
inches of soil and decreased with depth. In the middle zone it was 
twofold to threefold greater than in the upper zone and increased 
with depth. Sodium concentration in the lower zone was similar to 
that of the middle zone and exceeded 1,190 ppm at all depths. 
54 
