Summary of Vegetation Results 
Overall, cover by vegetation in tidal wetlands in the West was low, with bare area 
dominating both the quadrats and transects at many sites. The small number of 
vegetation species observed at each site makes it difficult to evaluate community 
patterns and the low frequency of occurrence of most species makes it difficult to 
evaluate patterns of individual species across the study area. Observed geographic 
patterns in major plant groups may be attributed to differences in habitat type among 
the three states. The higher abundance of emergent macrophytes in California and San 
Francisco Bay sites may be attributed to the predominance of marsh habitat in these 
areas. The higher abundance of seagrass and macroalgae in Washington may be 
attributed to the predominance of tidal flat habitat and lack of marsh habitat in this state. 
Oregon tidal wetlands were a mixture of habitat types and subsequently, these sites 
contained a mixture of vegetation groups. 
Plant cover data generated from vegetation quadrats and vegetation transects 
were very similar throughout the study area. Geographic trends in major plant groups 
and common individual species were similar for quadrat and transect data. Species 
richness throughout the study area was slightly higher and relative cover of bare area 
was slightly lower for transect data than quadrat data. These findings may be attributed 
to the fact that sampling area was larger for transects (5-m length) than quadrats (0.25 
m 2 ). Vegetation sampling in tidal wetlands often employs much longer transects (for 
example 30-m; Bertness and Ellison 1987) running perpendicular to the shoreline to 
capture heterogeneity in tidal wetland vegetation in response to gradients in inundation 
and salinity. As transects in this study were short and were established parallel to the 
shoreline, they would not be expected to capture this variation in vegetation, potentially 
resulting in the low number of species encountered at most sites. 
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