San Francisco StateUniversityGeography Department Geography 316: Biogeography The Biogeography of Spartina Foliosa By Brendan Thompson send comments: bholzman@sfsu.edu OR whatnots@yahoo.com |
Figure 1: Inflorescence of S. foliosa © Br. Alfred Brousseau, Saint Mary's College |
TAXONOMY
The taxonomy of Spartina foliosa, also known as California cordgrass, or
Pacific cordgrass breaks down as follows:
The Kingdom is Plantae, commonly known as plants.
The Subkingdom is Tracheobionta, vascular plants.
The Superdivision is Spermatophyta, seed plants.
The Division is Magnoliophyta, flowering plants.
The Class is Liliopsida, monocotyledons.
The Subclass is Commelinidae.
The Order is Cyperales.
The Family is Poaceae, the grass family.
The Subfamily is Chloridoideae.
The Tribe is Chlorideae.
The Genus is Spartina, cordgrass.
And the Species is S. foliosa.
DESCRIPTION
Spartina foliosa grows to 140 cm tall with blades 8-12mm wide (Josselyn and Bucholz 1984). The leaves are distichous, where the leaf/blade is divided into two symmetric rows. Its flowers appear in clusters along the grass stalk, in groups of 12-25cm (figure 1). This quality is called its inflorescence. In the San Diego Bay, it is found between the elevations of .5 and 1.2 m NGVD (Zedler et al 1999). The closer the proximity to a tidal channel, or at the lower reaches of its elevation range, the taller S. foliosa can grow (Cain and Harvey 1983).
REPRODUCTION
Spartina foliosa is a flowering plant, also known as an angiosperm. It engages in sexual and asexual reproduction. Reproduction is carried through either by self regeneration, pollination, or through the transfer of pollen from one flower to another by wind or water. In the San Francisco Bay area, S. foliosa flowers June through September (Anttila et al 1998). A pollinated flower produces a seed that may grow into a plant. Come November in the San Francisco Bay area, Spartina foliosa can reproduce from a dropped seed, but it has an extremely low success rate in germinating (Trnka 1998). S. foliosa also produces relatively small amounts of pollen, which lessens its success producing seed (Anttila et al. 1998). Most commonly, an individual plant will asexually reproduce year-round (Trnka and Zedler 2000) sprouting a clone from a rhizome. A rhizome is an underground stem that has the capacity to vegetatively reproduce by sprouting a clone of the parent plant. Clones are most likely to be produced after fresh-water flooding (Zedler et al. 1992).
RANGE
This particular perennial grass is endemic to central and southern California coastal salt marshes (Map 1), and is found as far south as Baja. Its northerly endemic range is Sonoma County (Strong 1995), but it can be found in the far north of California, where it has been introduced into Del Norte County. The most frequently studied areas of S. foliosa habitat are sites in San Diego County and on the shores of the San Francisco Bay. According to Trnka and Zedler (2000), the largest stands in Southern California are found in these six coastal salt marshes: San Diego Bay, Bolsa Chica, Mission Bay, Tijuana Estuary, Upper Newport Bay, and Anaheim Bay. |
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Spartina foliosa is found throughout San Francisco Bay in varying concentrations. The North Bay intertidal zones of Marin, Sonoma, and Contra Costa have many pure stands of S. foliosa, whereas the East Bay area intertidal zones of Alameda County contain mostly hybrids of S. foliosa that have cross-pollinated with the competitor grass Spartina alterniflora (Ayres 1998). Other California counties where it has been documented as an established species are Marin, Napa, Solano, Alameda, and Santa Barbara (CalFlora 2001).
Spartina foliosa is found in coastal salt marshes, or areas of land that are periodically subject to tidal inundations of seawater. Because S. foliosa requires this daily flushing of surface salts (Josselyn et al. 1993), its range is restricted to areas around the upper inter-tidal areas (Strong and Daehler 1995). It doesn’t possess the resiliency to survive on lower elevation mudflats like other Spartina species can, S. alterniflora in particular (Callaway and Josselyn 1992). In areas dominated by S. foliosa, the neighboring bare, or open intertidal mudflats provide a valuable resource for migratory birds and other organisms.
The soil it grows in is very alkali, or salty. S. foliosas ability to grow in this saline environment earns it the label of a “halophyte.” The roots of these grasses are able to take in seawater while excluding the salts. Although it is a halophyte, its growth rate would increase in a less saline environment (Phleger 1971).
Since these are C4 photosynthesizing plants, they are able to efficiently retain water and assimilate CO2 when air temperature is high. Like many other salt marsh plants, the limiting factor to its growth is the presence of soil nitrogen.
S. foliosa grows best in pure stands, as it is a poor competitor with other plant species. Pure stands will only be found on creek banks, bay peripheries, or in deeper tidal pools (Zedler et al. 1999). A population of S. foliosa will appear in several clusters, each cluster being the result of vegetative reproduction. The resulting patchwork allows space in between colonies for incoming seawater to come and go. |
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The patches will grab sediment from the outgoing water, contributing to a process called accretion. The process of accretion is what puts the “land” into wetland.
The first grasses to come into being were C3 photosynthesizers. The earliest fossils identifying a specific grass type are from 58 million years ago and belong to the bamboo family. These grass types are representative of a cooler climate with a forested environment. Although it is likely grasses evolved with the appearance of angiosperms (flowering plants) some 65-135 million years ago in the Cretaceous period, reliable pollen fossils are only available from the Paleocene epoch of the Tertiary period, (54-65 million years ago). Gaining insight into the history of grasses from this period is difficult, as the pollen fossils don’t offer any unique attributes that enable grass varieties to be discerned.
As the Oligocene epoch was giving way to the Miocene 26 million years ago, the climate of the earth was becoming more arid, creating an environment that would allow for evolution of the C4 photosynthesizing grasses. It is here, from within the Miocene epoch (between 7-15 million years ago) that the ancestors of S. foliosa first flourished (Chapman 1996).
| Figure 2 shows a cladogram of grass subfamilies. S. foliosa is a member of the sub-family chloridoideae, and this cladogram shows that S. foliosa shares a common ancestry with all the other sub-families listed. However, this cladogram doesn't represent the definitive evolution of these grasses, as new information about their evolution is still being discovered. |  |
figure 2: Relationships of the subfamilies of the Poaceae. |
It is nearly impossible to find any information about Spartina foliosa without accompanying mention of S. alterniflora. S. alterniflora, also called smooth cordgrass, is an Atlantic and Gulf Coast marsh grass that was introduced to the west coast approximately 25 years ago (Ayers et al. 1999). It is an invaluable species on the east coast for erosion control and animal habitat, but here it has a great capacity to alter the tidal marsh ecosystem. S. alterniflora populations grow in dense stands, blocking the in and outflow of seawater, and trapping sediments at a high rate. The level of accretion skyrockets as the alien cordgrass blankets a significant portion of what was once an open mudflat, effectively turning it into a homogenous meadow of smooth cordgrass. Lost mudflat areas represent a loss of rare and invaluable shorebird and invertebrate habitat.
S. alterniflora also hybridizes with S. foliosa, leading to the dilution of the S. foliosa phylogeny. S. foliosa has no chance of surviving as a species where S. alterniflora has been introduced, as S. alterniflora possesses much greater fitness than S. foliosa (Anttila et al 1998). It is reasonable to predict that without intervention S. foliosa will go extinct in San Francisco Bay.
The human threat to S. foliosa shouldn’t be overlooked. 75% of California coastal wetlands have been destroyed since the mid 1800’s (Marcus and Kondolf 1989). More than 75% of Southern California salt marshes have been destroyed by human development (Langis et al. 1991). It is important to keep the remaining natural salt marshes intact, as efforts to construct wetlands have failed to approximate levels of productivity and function that natural wetlands possess.
Attempts to restore S. foliosa to salt marshes have not been an easy task. Because an easy way to produce S. foliosa from seed has not been found, the transplanting of S. foliosa soil plugs has been the approach most often used. Also, a sought after, but not easily accomplished goal is encouraging S. foliosa in constructed marshes to grow to adequate heights for light-footed clapper rail nesting (Zedler 1993). Trnka and Zedler (2000) came to the conclusion that the genetic constitution of the grass is not the determining factor of whether or not the grass will grow near the upper end of its height range. Instead, the quality of the marsh environment, such as levels of sediment nitrogen, will have more of a deciding factor. Because of this, it is not necessary to obtain the best and tallest naturally occurring specimen for transplanting. Moreover, by taking the choice S. foliosa specimens from their established habitat, prime and endangered clapper rail habitat would be sacrificed for a project with little chance of success (Trnka and Zedler 2000). Nitrogen fertilization to encourage growth should only be applied to pure stands of S. foliosa, as nitrogen supplementation will most likely encourage growth of a superior plant competitor (Boyer and Zedler 1999).
LINKS
California Coastal Conservancy
Alien Cordgrasses in Pacific Estuaries
Anttila, Carina K.; C.C. Daehler; N.E. Rank; and D.R. Strong. 1998. Greater male fitness of a rare invader (Spartina alterniflora, Poaceae) threatens a common native (Spartina foliosa) American Journal of Botany 85(11). 1597-1601.
Ayres, D.R.; D.G. Rossi; H.G. Davis and D.R. Strong. 1999. Extent and degree of hybridization between exotic (Spartina alterniflora) and native (S. foliosa) cordgrass (Poaceae) in California, USA determined by random amplified polymorphic DNA (RAPDs). Molecular Biology v 8. 1179-1186. 19-35.
Boyer, Katharyn E.; J.C. Callaway; and J.B. Zedler. 2000. Evaluating the progress of restored cordgrass (Spartina foliosa) marshes: belowground biomass and tissue nitrogen. Estuaries. 23(5). 711-721.
Cain, D.J. and H.T. Harvey. 1983. Evidence of salinity induced ecophenic variation in cordgrass (Spartina foliosa Trin.). Madrono. v 30. 50-62.
CalFlora: Information on California plants for education, research and conservation. [web application]. 2000. Berkeley, California: The CalFlora Database [a non-profit organization]. Available: http://www.calflora.org/cgi/calflora_query?special=calflora&where-calrecnum=7701&one=T [Accessed: Nov 1, 2001].
Callaway, J.C.; and M.N. Josselyn. 1992. The introduction and spread of smooth cordgrass (Spartina alterniflora) in South San Francisco Bay. Estuaries. v 15. 218-226.
Chapman, G.P. (1996) The Biology of Grasses. CAB International, pp103-125.
Fennessy, S.; J. Book.; A. Rokosch. Case study 3: limited response of cordgrass (Spartina foliosa) to soil amendments in a constructed marsh. Kenyon college web page on restoration ecology. http://www2.kenyon.edu/depts/biology/projects/biol493/pages/Case%20Study%203.htm. [Accessed on 11/12/01].
Greer, P.J. 1998. Seed depth, elevation, and sedimentation effects on Spartina foliosa germination, growth and mortality. MA thesis, San Francisco State University.
Hickman, J.C. 1993. The Jepson Manual: higher plants of California. University of California Press. 1400p.
Josselyn, M.N. 1983. The ecology of San Francisco Bay tidal marshes: a community profile. Slidell, LA. U.S. Fish and Wildlife Service. 102 pp.
Josselyn, M.N.; and J.W. Bucholz. 1984. Marsh restoration in San Francisco Bay: A guide to design and planning. Technical Report #3 Tiburon Center for Environmental Studies, San Francisco State University. 104 pp.
Langis, R.; M. Zalejko; and J. Zedler. 1991. Nitrogen assessments in a constructed and a natural salt marsh of San Diego Bay. Ecological Applications. v 1. 40-51.
Larsson, B.C. 1996. A comparative investigation of accretion rates in Spartina alterniflora and Spartina foliosa. MA thesis, San Francisco State University.
Marcus, L., and A. Kondolf. 1989. The coastal wetlands of San Diego County. Report of California State Coastal Conservancy, Sacramento.
Mobberly, D.G. 1956. Taxonomy and distribution of the genus Spartina. Iowa State College Journal of Science. v 30. 471-574.
Phleger, C.F. 1971. Effect of salinity on growth of a salt marsh grass. Ecology. v 52. 908-911.
Strong, Donald R.; and C.C. Daehler. 1995. Alien cordgrasses in pacific estuaries. California Exotic Pest Plant Council 1995 Symposium Proceedings.
The CalFlora Database. CalFlora Taxon Report. Spartina folios. http://www.calflora.org/cgi/calflora_query?special=calflora&where-calrecnum=7701&one=T [Accessed on 10-9-01].
Trnka, S.; and J.B. Zedler. 2000. Site conditions, not parental phenotype, determine the height of Spartina foliosa. Estuaries. v 23. 572-582.
Trnka, S.J. 1998. Environmental and parental height form effects on the growth of Spartina foliosa in Southern California. M.S. Thesis. San Diego State University, San Diego.
USDA Natural Resources Conservation Service. Plants Profile for SPFO. http://plants.usda.gov/plants/cgi_bin/plant_profile.cgi?symbol=SPFO&rtnscr=qurymenu.html [Accessed on 10/09/01].
Zedler, J.B.; C.S. Nordby; and B.E. Kus. 1992. The ecology of Tijuana Estuary: a National Estuarine Research Reserve. Washington DC: NOAA Office of Coastal Resource Management, Sanctuaries and Research Division.
Zedler, J.B.; 1993. Canopy architecture of natural and planted cordgrass marshes: selecting habitat evaluation criteria. Ecological Applications. v 3. 123-138.
Zedler, J.B.; J.C. Callaway; J.S. Desmond; G. Vivian-Smith; G.D. Williams; G. Sullivan; A.E. Brewster; and B.K. Bradshaw. 1999. California salt marsh vegetation: an improved model of spatial pattern. Ecosystems. v 2. 19-35.