Distribution of seed plants with respect to tide levels and water salinity in the natural tidal marshes of the northern San Francisco Bay Estuary, California

Atwater, Brian F.; Hedel, Charles W.

doi:10.3133/ofr76389

Cited by 25 publications

(31 citation statements)

References 12 publications

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“…The results of this analysis were generally consistent with past studies that include quantitative vegetation samples from the Bay-Delta (Atwater and Hedel 1976;Atwater and others 1979;Watson and Byrne 2009). At a regional scale, tidal wetland vegetation in the Bay-Delta is influenced by ambient salinity regimes (Figure 4).…”

Section: Discussionsupporting

confidence: 79%

“…Since their design was based on Atwater and Hedel (1976), who originally sampled a comparatively small transect at Sand Mound Slough compared to South Hampton Bay and Hill Slough, this is understandable. As pointed out, in a comparison of richness at the 1,000-m 2 plot scale between Rush Ranch, Browns Island, and Sand Mound Slough, Rush Ranch had the highest richness; whereas at the site_all scale (20,000 m 2 ), Sand Mound Slough had 12 more species than Rush Ranch (Table 2).…”

Section: Patterns Of Bay-delta Tidal Wetland Plant Species Diversitymentioning

confidence: 99%

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Tidal Wetland Vegetation in the San Francisco Bay-Delta Estuary

Vasey¹,

Parker²,

Callaway³

et al. 2012

SFEWS

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We analyzed tidal wetland vegetation patterns in the San Francisco Bay-Delta estuary (Bay-Delta) and discuss their significance for future conservation. Our objective was to conduct a balanced, random sample of six historic "remnant" tidal wetlands along a salinity gradient that ranged from southern San Pablo Bay to the lower Delta. We also wanted to compare diversity among these sites at five different scales, ranging from small subplots to total species per site. We randomly established twenty 0.1-ha plots at each site, and sampled ten 7-m 2 circular subplots (subplot scale) in each plot for species presence and cover. We calculated total species per plot (plot scale) and total species per site (site scale) based on these subplot data. We calculated importance values for each species found in subplots based on frequency of occurrence and proportion of total cover at each site. In addition, we recorded species found within the 0.1-ha plot but not sampled in subplots (plot_all scale), and calculated the total species for each site based on these plot_all data (site_all scale). Thus, richness at each site was evaluated at five different scales that ranged from 7 m 2 to 20,000 m 2 . We conducted a one-way ANOVA that compared mean richness among three scales with continuous data: subplot, plot, and plot_all. At lower estuary (San Pablo Bay) sites, richness values at these three scales were significantly lower than upper estuary (Suisun-Delta) sites. In Suisun-Delta sites, significant differences in richness varied, depending on sampling scale. Rush Ranch, a brackish wetland, had the highest average number of species per plot, whereas Sand Mound Slough, a freshwater wetland, had the highest average number of species at the subplot scale and the most total species at the site_all scale. Sand Mound Slough also had the highest number of unique species (22) compared to the other sites. We found a strong negative correlation (r 2 = 0.99) between total species number and salinity (the most in the Delta at the lowest salinity, and the least at China Camp with the greatest salinity). Our analysis suggests the following conservation recommendations: (1) restore habitat for freshwater plant species diversity in the Delta; (2) restore transitional brackish wetland habitat in salt marshes of the San Pablo Bay and San Francisco Bay; and (3) focus on control of pepperweed (Lepidium latifolium) in brackish marshes.

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Section: Discussionsupporting

confidence: 79%

Section: Patterns Of Bay-delta Tidal Wetland Plant Species Diversitymentioning

confidence: 99%

Tidal Wetland Vegetation in the San Francisco Bay-Delta Estuary

Vasey¹,

Parker²,

Callaway³

et al. 2012

SFEWS

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“…1; see supplementary material). These transects were originally established and surveyed by USGS scientists in the 1970s (Atwater and Hedel 1976) due to concerns about the effects of future water diversions on tidal marsh ecology. These transects were established specifically to inventory baseline conditions so that future change could be detected.…”

Section: Study Areamentioning

confidence: 99%

“…More specifically, these sites were chosen because these locations (1) contained areas of ''natural'' (i.e., Late Holocene) tidal marsh, (2) spanned the full salinity gradient of the estuary, (3) had experienced minimal hydrologic modifications, and no known subsidence due to groundwater or natural gas pumping, and (4) contained extensive mudflat-to-upland transitions to ensure the representation of all the habitat types. Atwater and Hedel (1976) described the vegetation of these marshes approximately three decades ago. Typically, the low marsh was dominated by Spartina foliosa where ambient water salinity was greater than 15%, and by Scirpus californicus, Phragmites australis, or Typha sp.…”

Section: Study Areamentioning

confidence: 99%

Abundance and diversity of tidal marsh plants along the salinity gradient of the San Francisco Estuary: implications for global change ecology

Watson

Byrne

2009

Plant Ecol

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From 2003 through 2005, tidal marsh plant species diversity and abundance on historically surveyed vegetation transects along the salinity gradient of the San Francisco Estuary were investigated to establish empirical relationships between plant distributions and environmental conditions, and furthermore to examine and predict past and future plant distribution changes. This study suggests that for most species, salinity is the primary control on plant distribution. Thus, ongoing changes in estuarine conditions (increasing sea level and salinity) are resulting in a complex mix of plant distribution changes. On the low marsh, where sediment salinity is similar to that of ambient water, halophytic species are replacing salt-intolerant taxa. However, on marsh plains, where increased tidal flooding is moderating high salinity (concentrated by evaporation), halophytic ''high marsh'' species are being replaced by salt-intolerant ''low marsh'' taxa. Thus, future changes in plant distributions will hinge on whether marsh sediment accumulation keeps pace with sea level rise.

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“…For San Pablo Bay, the geomorphic transition between mudflat and low marsh lies at or about the mean tide level (1 m below mean higher high water, MHHW). The elevation at which this low marsh gives way to high marshplain occurs some 0.8 m above mean tide level (at or about 0.2 m below MHHW) (Atwater and Hedel 1976;Goals Project 1999). These transitions are for established vegetation, though there are some data (Siegel 1998;authors' unpublished data) showing that mudflats must reach a higher elevation, near 0.4 m above the mean tide level, before they will colonize rapidly by seed or fragment.…”

Section: Restoration Approaches In the Baymentioning

confidence: 99%