C\J 



E 



O) 



c 



E 



CD 



o 



100 

 90 

 80 - 

 70 - 

 60 - 

 50 

 40 H 



30 



19 



Spartina foliosa 

 TSL — 1 



Salicornia virginica 

 Mean Cover 



78 



— i — 



1980 



1 



1982 



1984 



1 



1986 



1 



1988 



Figure 5.4. Reciprocal shifts in the abundance of cordgrass (Spartina foliosa) and 

 pickleweed (Salicornia virginica) over the 10-year monitoring program. Flooding 

 occurred in 1980 and 1983; nontidal drought occurred in 1984. Data are from the 

 original 102 lower-marsh sampling stations, with means only for quadrats where the 

 respective species occurred (n < 102). TSL = total stem length. 



Pickleweed may thus have slowed the recovery 

 of cordgrass occurrences (Figure 5.3), even 

 though it appears not to have slowed its 

 biomass recovery in stations where it 

 managed to re-invade (Figure 5.4). 



The return of tidal conditions in 1985 was 

 followed by a gradual recovery in cordgrass 

 total stem length and pickleweed cover. 

 Interestingly, cordgrass continued to increase 

 in TSL to a new high in 1988 (note that means 

 are for stations of occurrence only). Thus, 

 even though the distribution of cordgrass was 

 far more restricted than in 1979-83, the 

 growing conditions were better where it 

 occurred. Likewise, although pickleweed 



expanded its distribution after 1984, its 

 average cover declined annually thereafter. It 

 is likely that dredging in 1987 (Entrix et al. 

 1991) increased overall tidal flows, which 

 should have favored cordgrass. It is unlikely 

 that cordgrass outcompeted pickleweed to 

 force its decline. Nor is it likely that these 

 1986-88 trends will continue. This will be 

 tested with the 5-year recensus in 1993 (see 

 plan in Section 5.5). 



5.3.2 Responses of the Mid-Elevation Marsh 

 to Nontidal Drought 



There were several changes in the mid- 

 elevation marsh plain, which is dominated by 

 pickleweed. The 1984 expansion of the 

 monitoring program to include 115 quadrats 

 beyond the cordgrass habitat provided an 

 opportunity to compare species distributions 

 over a much larger spatial scale, as had been 

 done in 1974 (a sample of 357 quadrats 

 across the marsh plain, Zedler 1977). With 

 data across the marsh plain, it was possible to 

 document species compositional changes 

 between 1974 and 1984. Additional 

 information was obtained in 58 stations used 

 for productivity measurement in 1976 

 (Winfield 1980) and 9 quadrats along one 

 transect used for a study of annual pickleweed 

 (Salicornia bigelovii) in 1975 (Zedler 

 1975). While less extensive, these interim 

 censuses helped to determine when 

 compositional changes occurred. All sampling 

 assessed species composition with the same 

 cover classes and 0.25-m 2 circular quadrats, 

 so that data are readily comparable. 



1 04 



