The tidal surge in August produced similar decreases in 

 vegetation cover at Station II (Figures 6-20a and 

 6-20b). The transect was then flooded by fresh water 

 through the Rincon Overflow Channel several days 

 later. Bare area had decreased by ~11% in December 

 1999, following the event. By June 2000, bare area had 

 decreased by —40% and Salicomia bigelovii had invaded 

 ~50% of the transect in areas that were previously 

 bare. 



In January 1999, the most significant change was the 

 appearance of Salicomia virginica in the back section of 

 the transect (Figure 6-21 c). However, the cover had 

 decreased to levels below the 50% mapping level in 

 June 1999. An increase in Batis maritima also occiured 

 in the spring following the event (Figure 6-21d). No 

 obvious vegetation changes occurred in the transect at 

 Station III following the tidal surge or the freshwater 

 flow through the channels during the September 1999 

 event. 



Leaf Area Index 



Vegetation maps showing the LAI distribution within 

 and between the transects indicate that overall fohage 

 density varied considerably. At the Reference Station, 

 LAI values were highest in January and June 1998 and 

 June and December 1999 (Table 6-6). The high 

 LAI values appear to coincide with high Monanthodoe 

 littoralis cover (Figures 6-14d and 6-23e). M. littoralis 

 also appears to be responsible for high LAI values in 

 June and October 1998 and December 1999. In June 

 1999, high LAI values corresponded to high Batis 

 maritima cover in addition to Monanthodoe cover. 



At Station II, LAI values were consistendy lower than 

 the other stations (Table 6-6). However, increases in 

 values were seen in August 1997, following the 

 July 1997 event. The increased values occurred in the 

 same area of the transect as the increased Batis maritima 

 growth (Figures 6- 15b and 6-24c). High LAI values in 

 June 1998 coincide with Monanthodoe littoralis and 

 Borrichia frutescens cover (Figures 6- 12c and 6-24f). In 

 June 1999, the greatest LAI values occurred where 

 Salicomia bigelovii cover was high (Figures 6-1 2d and 

 6-24J). Low LAI values correspond to high bare areas. 



LAI values at Station III were typically higher than the 

 other stations (Table 6-6). The highest values were in 

 the spring (Figure 6-25) and were lowest in areas with 

 little to no vegetation. 



BlOMASS 

 Batis Maritima 



Batis maritima biomass showed no obvious seasonal 

 trends or event-mediated responses (Table 6-7). 

 Biomass at all three stations ranged between 643 and 

 3,878 g/m' Lowest values occurred at the Reference 

 Station m May 1996 (1,016 g/nr) and February 1997 

 (1,201 g/m"^. The lowest value recorded at Station II 

 was also in May 1996 (643 g/m^. Low values occurred 

 on the same dates at Station III as well (1,180 and 

 805 g/m", respectively). Simultaneous occurrence of 

 the low values between stations does not appear related 

 to hydrographic conditions. At the Reference Station, 

 biomass values peak in June 1997 (3,208 g/m"^, and 

 gradually declined by more than half to 1,379 g/m' in 

 June 1999. B. maritima biomass did not exhibit the 

 same trend at the other two stations. 



Borrichia Frutescens 



Borrichia frutescens has the greatest range of biomass 

 values and the greatest total biomass of the four 

 species sampled (Table 6-7). Values between the 

 stations were within the range of 1,948 to 10,412 g/m^. 

 At all three stations, the highest values were seen at the 

 beginning of the study period. At the Reference 

 Station and Station II, high values of 8,053 and 

 8,575 g/m*, respectively, were measured on May 1996. 

 At Station III, the highest values measured were in 

 February 1996 (10,412 g/m") and 1997 (9,848 g/m"). 

 Biomass gradually decreased over the study period for 

 all three stations. 



Chapter Six ♦ 6-37 



