reached near 10% (Figure 6-8e). Cover decreased 

 during the fall mondis foUowing the plant's annual life 

 cycle (i.e., annual plants complete their life cycle within 

 a year). Cover increased dramatically from < 1% to 

 52% between January and June 1999. The increase in 

 S. bigelovii occurred the summer following the October 

 1998 composite hydrographic event [i.e., the period 

 between the October 1998 and June 1999 sampling 

 periods), during which a positive net flow of over 

 4,160 10' m' (3,372 acre-ft) entered Rincon Bayou. 

 The Rincon Overflow Channel was activated during 

 Event 25, consequendy flooding the station. The 

 increase in growth corresponded to a period where 

 11 out of 14 months received over 5 cm (2 inches) of 

 rain. 



The late fall 1998 event significandy lowered open 

 water salinity values at Station II from about 45 ppt 

 (June 1998) to about 11 ppt Pecember 1998). Open 

 water salinity concentrations were also lowered by 

 precipitation in the fall 1997 (October), which kept 

 early winter salinity values below 15 ppt as well. The 

 only spring without Salicomia bigelovii ^o^^jth was 1997, 

 most likely because a fall event did not occur in 1996 

 and winter salinity values were relatively high (46 to 

 58 ppt) compared to the other years. 



An increase in cover at Station II during June 1999 

 coincided with an increase at the Reference Station. 

 However, the increase at Station II was almost twice 

 that of the Reference Station. In June 1 998, the 

 percent cover of i". bigelovii ^^s almost identical at the 

 reference and Station II (Figures 6-7e and 6-8e). In 

 this instance, late winter salinity concentrations were 

 lowered by rainfall at both stations. Prior to June 

 1999, winter salinity values at Station II were lowered 

 as a function of freshwater flow through the channels, 

 possibly explaining the almost doubling in S. bigelovii 

 cover at Station II compared to the Reference Station 

 that summer and the increase compared to the 

 previous year. 



A similar increase in S. bigelovii cover was seen in the 

 summer 2000. Cover in June 2000 at Station II was 

 41%, while cover at the Reference Station was only 

 12%. Once again, the differences are most likely a 

 result of the hydrographic event that activated the 



Rincon Overflow Channel in September 1999 

 (Event 36). The difference in cover between the June 

 1999 and June 2000 sampling dates at Station II may 

 be indicativ^e of the tuning of the flow event. The 

 1999 event occurred in the late summer, while the 1998 

 event occurred during the fall and was followed by 

 several months of consistent precipitation. 



Bare Area - At Station II, increases (> 2 %) in 

 Salicomia bigelovii cover corresponded to decreases in 

 bare area (r^ = 0.64) (Figures 6-8e and 6-8f). During 

 June 1999, S. bigelovii cover was about 50% and bare 

 area decreased about 33%, the largest decrease in bare 

 area obser\'ed during the study period. Bare area was 

 highest (81%) in September 1999, which was similar to 

 the peak found at the Reference Station (69%). 



Station III 



Batis maritima — Total transect percent cover of Baiif 

 maritima exhibited a similar pattern to that seen at the 

 Reference Station (Figure 6-9a). Cover cycled 

 seasonally, and the greatest increase in cover (9.7% to 

 37%) occurred between February and August 1997. In 

 general, percent cover at Station III varied between 

 10% and 37% and was greater than the other two 

 stations. 



Borrichia frutescens - At Station III, percent total 

 percent cover oi. Borrichia frutescens vincA between 10% 

 and 25% (Figure 6-9b). No correlation was seen with 

 Batis maritima {f — 0.05). Total cover oi B. frutescens 

 declined gradually from February 1997 (25%) to near 

 11% in December 1999. 



Salicomia virginica - Distichlis spicata was not a 

 dominant species at Station III, so Salicomia virginica 

 was analyzed instead because it occurred at Station III 

 (Figure 6-9c). However, this species was rarely found 

 at the other two stations. S. virginica cover was greatest 

 in February 1996 (23%) but decreased to 12% in May 

 1996 and continued to decline to 6.5% in August 1997. 

 The low cover occurred following the July 1 997 event. 

 Cover remained relatively low until October 1998, 

 when it began to gradually increase to 16% in 

 December 1999. The increase occurred after the 



6-20 



V^egetation Communities 



