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Compilation of Focus Teams and Hydrogeomorphic Advisory Team Recommendations: Plant Focus Team Recommendations

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Contents

Plant Focus Team Recommendations

Fish and Aquatic Invertebrate Focus Team Recommendations

Mammals, Amphibians, Reptiles and Terrestrial Invertebrates Focus Team Recommendations

Shorebirds and Waterfowl Focus Team Recommendations

Other Birds Focus Team Recommendations

Integrating Abiotic Factors in the Goals Project: Tenets of the Hydrogeomorphic Advisory Team

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Notice

The following is a compilation of the recommendations produced by each of the focus teams and the HAT. You will note that some of the terminology used in these reports differs from that used in the Goals Report. For example, some teams discuss regions and subregions that are defined differently, and some use different names for habitats. This is because the terminology used within the Project has evolved over time, and some has been developed specifically to facilitate presentation of the Goals.

In order to preserve the original intent of the focus team authors, no changes, other than minor formatting changes, have been made in the teams' reports. We believe the intent of their recommendations is made clear by the information contained in the reports.

Plant Focus Team Recommendations

The Plant Focus Team submits these recommendations regarding marsh restoration in the San Francisco baylands. Included is an introductory section on estuarine plant community objectives. Each recommendation includes descriptive background information and supporting rationale. For additional information regarding the plant communities of the baylands ecosystem, please refer to the community narratives that will be compiled in the Goals Project's Focus Team Species/Community Narrative Report.

1. Overall estuarine plant community objectives. From the perspective of plant community conservation, the Plant Focus team recommends the following objectives as the highest priorities for conservation of plant associations and rare plants in the San Francisco Bay estuary:

(1) protection of existing tidal marshes against further artificial losses and degradation;
(2) extensive restoration of whole tidal marshes systems (not just pocket marsh indentations within a matrix of levees that separate them from the historic bay margin) and restoration of associated ecotonal estuarine-margin plant communities (e.g. freshwater riparian wetlands, vernal pool and swale grasslands, alluvial seasonal wetlands).

Tidal restoration of diked historic baylands (former marsh and mudflat) typically displaces non-tidal salt marsh, brackish marsh, freshwater seasonal wetland plant communities, and salt pans. While most diked wetland plant associations are less diverse and contain more exotic species than tidal marshes, some contain important populations of regionally rare plants which have been eliminated from their original communities in the ecosystem (e.g. subsaline vernal pools, alluvial terraces). The weedy character of much diked wetland vegetation is merely a contingent feature of past degradation from adverse land management practices (discing, ditching, filling), not an essential feature. Diked wetlands should therefore not be presumed to support entirely ruderal floras or degraded non-tidal salt marsh. They should be carefully assessed individually for regionally important plant associations before they are converted to tidal marsh, and some should be conserved and enhanced if they support scarce plant associations that cannot feasibly be replaced.

Tidal marsh restoration typically involves either passive sedimentation or engineered placement of dredged material to develop new marsh substrate in subsided diked baylands. These measures produce youthful marsh systems with little soil development, relatively little microtopographic differentiation, and usually support relatively low native plant species diversity. Well-developed and complex microtopography and marsh soils are often necessary for viable populations of rare tidal marsh plant species. Restoration designs should therefore be adapted to include structural features which will facilitate development of mature marsh features, while avoiding compromising natural marsh succession (e.g. gently sloping upland transition zones with suitable soils). This is particularly important along the upper marsh profile, where ponds, streams, alluvial deposits and upland soils form complexes of ecotonal plant communities that naturally supported high diversity of native plant species which have declined significantly since most of the tidal marshes were diked.

The Plant Focus Team has chosen to use plant communities rather than species as the ecological units for conservation planning of the estuary. This is partly because more is understood about the ecology of the habitat in which rare species occurred than about the species themselves, particularly for species which are now regionally extinct or reduced to minimal remnants of their original populations. It is also partly because many rare species are united by similar and related habitat requirements, often associated with the high marsh zone. For the plant communities considered, it would be arbitrary and unrealistic to prescribe specific acreages of plant associations as habitat goals at this regional level of planning. This is because plant associations and populations are highly dynamic in density, distribution, and area. Moreover many rare plant populations, particularly rare annuals, are likely to exhibit fluxes of local extinctions and colonizations, often in concert with disturbances or environmental fluctuations. Instead, the Plant Focus Team is prescribing conservation priorities for the bay ecosystem's plants which would apply to opportunities to acquire, manage or restore diked baylands and adjacent lands as they become available.

2. Natural geographic variation in marsh structure and composition should be incorporated into marsh restoration designs and objectives. In planning marsh restoration in the SF Bay estuary, priority should be given to regenerating the full range of wetland types, local wetland habitats, and microenvironments within marsh systems. Much of the historic diversity of estuarine marsh was geographically embedded, reflecting local and subregional variations in substrate texture, wave energy, tidal energy, upland soils, upland drainages, etc. Some natural elements of the historic estuary are either extinguished or drastically reduced or altered, such as sandy backbarrier marshes, lagoon-fringe marshes, natural salt pans and marsh ponds, natural levees along channels and bayfronts, and alluvial fan/terrace ecotones. Plant communities and species which are now locally extinct or in severe decline depended on natural variation in marsh structure and composition.

Therefore, the Plant Focus Team recommends that potential restoration sites be examined carefully for their potential contribution to restore geographically unique, atypical, or important local marsh systems. Geographically specialized marsh restoration plans which fully consider opportunities to incorporate regionally scarce components of estuarine marsh systems are preferable to generic marsh restoration plans.

3. Restoration opportunities which link tidal marshes to upland and alluvial soils, seeps, drainages should be given high priority in restoration planning. Most tidal restoration sites are currently indented pockets in levee systems, separated from the historic margin of the estuary by subsided diked lands. The upper edge of such restored marshes are typically steep, disturbed levee slopes on unnaturally elevated bay mud substrate which often supports weedy vegetation. Most floristic diversity in tidal marshes was concentrated along the upper marsh edge, where transitions between high tidal marsh and local soils, seeps, and drainages created ecologically important variation in environmental conditions. Many rare or locally extinct plant species had high affinity for, or ecological dependence on, these transitional and diverse environments.

Therefore the Plant Focus Team recommends that opportunities to restore sites which connect tidal marshes to upland soils, creeks, seeps, be given at least as much priority as marsh restoration sites located adjacent to tidal sloughs.

4. The ecological restoration design of the upper marsh transition zones (ecotone) should be given as much priority as intertidal marsh. Upper marsh transition zones between high marsh and upland conditions are usually designed as buffer zones for wildlife, tidal refugia for wildlife, flood control components, public access and viewing areas, and maintenance access areas predominantly pragmatic management considerations rather than ecological ones. In contrast, intertidal marsh is usually designed as wildlife habitat or ecosystem restoration for its own sake. Because most floristic diversity in tidal marshes would occur in the upper marsh transition zone, restoration plans should treat it as a high priority area for restoration based on natural models and reference sites.

5. Exotic vegetation control and maintenance of existing native plant communities should be given consideration equal to restoration of marsh at new sites. SF Bay is subject to rapid invasion by exotic plant species which dominate whole marsh zones and displace native plant species (e.g. Lepidium latifolium and Spartina alterniflora). Some exotics displace rare and declining plant species and communities, such as upper marsh transition zones. Many newly restored marshes perhaps most are subject to rapid invasion and dominance by non-native marsh plants, significantly reducing the long-term ecological benefits of marsh restoration for biological diversity. Suppression of exotic plant invasion to newly restored marshes, which are less resistant to invasion than established marshes, is critical to the integrity of the plant communities they will support.

Therefore the Plant Focus Team recommends that restoration efforts be directed not just to restoration of new tidal marshes in degraded diked baylands, but also to restoration, enhancement, and management of existing estuarine marshes, including systematic efforts to suppress the spread of invasive exotic marsh vegetation, and eventually reduce and control their abundance. Highest priority should be given to early eradication of small, local invasions before they require major control efforts after "latency" (e.g. Spartina densiflora, S. patens); eradication of outpost "guerilla" colonies of established invaders (e.g. isolated outlier populations of Spartina alterniflora); and large-scale population control in habitats supporting rare plants which are at risk of being excluded by the invasive species (e.g. Lepidium latifolium in habitats of Cordylanthus mollis or Cirsium hydrophilum)

Natural, passive recruitment of marsh vegetation is appropriate as a restoration tool only when local dispersal rates by exotic plant species to the restoration site are low. Where recruitment rates of exotic species are unavoidably high, planting of native vegetation to provide a competitive advantage to native species is often justified. No large-scale tidal marsh restoration should proceed before local infestations of invasive exotic plants are suppressed. Exotic plant control should be considered to be an integral component of site preparation for restoration projects, equal in priority to earthmoving.

6. Reintroduction and introduction of rare plant species should be employed selectively as a restoration tool when appropriate opportunities arise. Some plant species in San Francisco Bay have become locally extinct because of urbanization, such as California sea-blite (Suaeda californica, federally listed as endangered) and California saltbush (Atriplex californica), or have become very rare in the estuary (e.g. Lasthenia glabrata, Lasthenia platycarpha, Castilleja ambigua, Cordylanthus mollis, Cordylanthus maritimus, Lilaopsis masonii).

Locally extinct plant species cannot disperse to potentially receptive restored habitats in San Francisco Bay from remote populations in a human time-scale. They should therefore be re-introduced from appropriate remant populations outside the S.F. Bay estuary when opportunities to restore receptive habitats for them arise. Furthermore, restoration projects should seek opportunities to establish receptive habitats for these species when feasible.

Rare plant species which still persist in the bay may be limited by dispersal between artificially fragmented suitable habitats, as well as by scarcity of suitable habitat. Reintroduction is an appropriate tool to compensate for artificial fragmentation of rare plant populations in the estuary. However, reintroduction should be designed to avoid adverse homogenization of genetically differentiated populations of rare species. Introduction of rare plant species to restoration sites which are not historically recorded to have supported them, but are within the ecological and geographic range of the species, is also appropriate for marsh restoration plans. Attempted translocation of rare estuarine plant populations to restored marshes as compensatory mitigation for degradation or elimination of rare plant populations at impact sites is unacceptable and should not be permitted, since replacement of an established rare plant population by an uncertain and potentially unstable one is inherently adverse for the conservation of the species.

7. Dredged materials should only be used selectively for marsh restoration. Bay mud and other sediments dredged from the estuary should be employed selectively in marsh restorations. Mineral-rich estuarine sediments should not generally be deposited at or above tidal elevations at which peaty organic material or adjacent upland soils would typically dominate the soil profile. Bay muds should not be deposited in the uppermost soil horizon of upper marsh transition zones unless used as a foundation material and are thickly capped with soil from terrestrial or alluvial (non-estuarine) sources. These restrictions are recommended because many rare marsh plants and associations of tidal marshes depend on the soil characteristics of peat-rich marsh soils and salinized, weathered upland mineral soils at the upland marsh edge, where soil texture and mineral composition is variable. Because marsh vegetation patterning is dependent on marsh drainage patterns, deposition of dredged materials above local Mean High Water, which inhibits differentiation of drainage patterns in subsequent marsh, should be discouraged (except where required for rapid development of endangered species habitat). Sites which historically supported relatively rare marsh substrates (e.g. sandy silts, sands, and interbedded alluvial sands, silts, clays) in the upper marsh zone should be restored with appropriate sediments. Levees used to contain dredged materials during filling operations should be removed to the greatest extent possible after placement of sediment, since levees screen out tidal litter that may be important in creating disturbance patches in tidal marsh.

8. Dry-season fresh wastewater discharges should be discouraged and reduced over time. Fresh wastewater discharges are a potentially useful resource for marsh restoration, but year-round high levels of discharges have contributed significantly to conversion of scarce salt marsh to brackish-fresh tidal marsh plant communities.

9. Refugial floras of diked wetlands should be surveyed before tidal restoration is proposed. While many diked wetlands are rich in exotic weedy species and poor in native species, some may (and do) act as refugia for species which were formerly found in tidal marsh edge environments, or adjacent seasonal wetlands, including species found in subsaline/alkaline soils of vernal pools. Since urbanization and agriculture have eliminated the original habitats of these species, their presence in diked wetlands may provide important refugia for geographically distinct populations. Diked wetlands should be subjected to careful seasonally timed surveys for spring flora species before diked wetland vegetation is presumed to be uniformly low in ecological value. Some diked baylands, particularly in the North Bay, should be conserved and artificially managed for hydroperiods that support surrogate grassland communities including vernal pool plant species.

10. Marsh restoration plans, designs, and objectives, should be based on empirical data. The use of generalized or arbitrary designs for plant community composition and vegetation structure should be discouraged. Plant community objectives should incorporate consideration of local geographic variability and historic conditions at the local and regional scale.

11. Outboard levees should be graded down to marsh level over long segments when tidal action is restored to diked basins, with some relict high fills left for tidal refugia used by marsh mammals and birds. This is to enable wave-driven debris (wracks, plant litter, peat rafts) to be dispersed across marsh plains during extreme tides, and to allow waves to propagate across shallow basins during brief periods of extreme inundation. These episodic disturbances dispersion of tidal litter, drift-smothering of vegetation, wave erosion of substrate at the high tide line are important long-term cyclic processes for creating vegetation gaps, and regenerating natural disturbances on which some rare plant associations and species depend upon.

12. Hypersaline microflora conservation (specialized microalgal and bacterial flora adapted to hypersaline conditions) should be achieved in the absence of a large industrial salt production system by any of three alternative methods:

(1) construction, operation, and maintenance of small-scale salt production systems at the pre-modern geographic scale (early 20th century family operated system, a few hundred acres), established by sub-dividing portions of the salt pond system at feasible locations (e.g. portions of Alameda shoreline);

(2) construction and maintenance of "short-circuited" managed salt evaporators within a restored tidal salt marsh complex, designed to produce only moderately hypersaline brine before internal dilution by large bay water intake during dilute winter tides. This would require construction of new or upgraded levees set back from the erosional open bay edge, and installation of additional tidegates for water management.

(3) construction of naturalistic, unmanaged facsimiles of historic marsh pans and salt ponds at appropriate locations within restored tidal marsh complexes. These would depend on construction of very low berms (less than 0.3 m above MHHW) across shallow basin floors near MHW elevation, passive overtopping by spring tides, and evaporative concentration of brines. Topography within the large basins should be irregular, so that internal relief causes variation in pond depth, and isolation of variable pockets of brine at different salinity during evaporative fall in pond levels. The concentration of brines would vary from hypersaline to crystallization in the largest basins. Such ponds would be constructed near the landward edge of restored tidal marsh in Alameda Co. These may be derived by construction of internal levees within existing salt ponds which are restored to tidal action, or they may be established in part by engineered placement of suitable dredged material. Pans equivalent to the smaller, mid-marsh depressions frequently flooded by spring tides ("drainage divide ponds") should be established artificially within some restored marshes to support near-marine salinity, to conserve viable populations of Ruppia maritima and support diverse macroalgae beds. Such pans would probably take many decades or more to form naturally.

To ensure adequate diversity of salinity regimes that control biological diversity of hypersaline microflora, the cumulative area of reconstructed salt ponds should be intermediate between the modern inflated extent, and the historic extent of the late 19th century. This is because the vast number of isolated, independent marsh pans that supported variability in hypersaline environments cannot be regenerated within the time-scale of restoration planning for tidal marshes.

13. Pace and scale of tidal marsh restoration should be regulated to avoid needless replication of design errors which become evident during monitoring, and to avoid excessive homogenization of even-aged restored marshes. Marsh diversity early in succession may reflect discontinuous, contingent events, such as rainfall variation, storm deposits of sediment, extreme tides, pulses of nutrients, freshwater flows, wrack deposits, variation in sediment supply or wind-driven sediment resuspension, etc. Results of large-scale pilot projects of tidal marsh restoration should be evaluated before regional conversion to tidal habitats is commenced in force. Such pilot projects, on the scale of 500 - 1500 acres, should be initiated as soon as possible, and incorporate replicated variation in various restoration designs and techniques.