An Overview of North Coast Grasses: Diversity and Distribution Across the
The North Coast of California, praised for its majestic forests and spectacular coastline, is less well known for its diversity of grasses. Numerous interesting native grasses are found in all of the region's varied habitats from coastal dunes to tidal marshes to redwood forests. Over a hundred grass taxa occur on the North Coast, several of which are rare or endemic to the area. This article offers an overview of North Coast grasses through the exploration of the region's distinctive natural communities.
Coastal dunes once were widespread all along the west coast, but through the combined impacts of development, off-highway vehicles, and the invasion of non-native species, only relatively small, fragmented patches of intact coastal dune habitat remain today. Although much of northern California's dunes have been degraded, the North Coast is home to arguably the most pristine coastal dune ecosystem remaining in the Pacific northwest: the Lanphere Dunes Unit of the Humboldt Bay National Wildlife Refuge. Located west of Arcata on the north spit of Humboldt Bay, approximately 475 acres of coastal dunes and estuary are protected in this area, which The Nature Conservancy managed for over 20 years prior to its transfer to the U.S. Fish and Wildlife Service in 1998. On this distinctively undisturbed stretch of coastline, along a beach that is remarkably free of the ubiquitous European beachgrass (Ammophila arenaria), here occurs one of the last remaining intact stands of Northern foredune grassland on the west coast (USFWS 1998).
Characterized by native dunegrass (Leymus mollis ssp. mollis) as the sole or dominant species in this vegetation series (Sawyer & Keeler-Wolf 1995), Northern foredune grassland is ranked by the California Department of Fish and Game as extremely rare at both the global (G1) and state (S1.1) levels (CDFG 2000). Restricted to the coast on the seaward edge of coastal dunes, stands of native dunegrass grow in the same habitat as European beachgrass, which has reduced and replaced this series all along the west coast (Sawyer & Keeler-Wolf 1995). European beachgrass was heavily planted on the North Coast in the 1960's for sand stabilization.
Native dunegrass is a beautiful member of the wheat tribe that occurs as far south as California's Central Coast and as far north as Alaska and over to Asia. When not growing in pure stands on the primary foredune, native dunegrass can be associated with species of the dune mat vegetation such as beach bursage (Ambrosia chamissonis), beach morning glory (Calystegia soldanella), European beachgrass, sand-verbena (Abronia spp.), sea-rocket (Cakile spp.), and large-flowered sand-dune bluegrass (Poa macrantha) (Sawyer & Keeler-Wolf 1995).
In addition to the native dunegrass a few other native grasses also occur on the coastal dunes of this region. Coastline bluegrass (Poa confinis), like large-flowered sand-dune bluegrass, is a dioecious Poa species of ocean bluffs and sand dunes. Both of these bluegrass species are at the southern extent of their range on the North Coast, occurring as far north as British Columbia. Red fescue (Festuca rubra) often can be found growing atop old relictual dunes that have not received fresh sand input for some time (K. Wear, pers. comm.). Red fescue is relatively widespread across California in a diversity of habitat types, but distinct forms of the species occur on the North Coast on sand dunes, ocean bluffs, and in salt marshes (Hickman 1993). In the hollows between dune ridges awned bent grass (Agrostis microphylla) can be found. This species is at the northern extent of its range on the North Coast, occurring as far south as Baja California. Awned bent grass prefers thin soils, sometimes growing on serpentine substrates and sometimes in vernal pools (hence its occurrence in the seasonal wetland hollows).
In addition to European beachgrass, a number of other weedy non-native grasses also invade coastal dune habitat. Silver European hair grass (Aira caryophyllea and A. praecox), quaking grass (Briza maxima), ripgut grass (Bromus diandrus), soft chess (B. hordeaceus), and annual fescue (Vulpia bromoides) are common invasives that occur not just on coastal dunes, but roadsides, grasslands, and other disturbed habitats. The invasion of coastal dunes by non-native annual grasses has been facilitated by the invasion of another non-native species in the North Coast region: yellow bush lupine (Lupinus arboreus). Like European beachgrass, yellow bush lupine, which is native to California as far north as the Bodega Bay area, was heavily planted on the North Coast by lumber companies and the Division of Highways for sand-stabilization. As a member of the legume family yellow-bush lupine has the ability to fix nitrogen in the soil, helping to make a normally inhospitable growing environment suitable for these invasive annuals.
Fortunately, weed eradication efforts targeting yellow bush lupine, European beachgrass, the annual grasses, and other non-native species of the coastal dunes have been successful. Native species naturally recolonize weed-free dunes, and much of the natural coastal dune habitat on the north spit has been restored. Maintenance of the North Coast's pristine coastal dunes is a never-ending battle, however, in the midst of a sea of encroaching invasives.
Coastal Salt Marsh
Most of the North Coast's salt marsh habitat is centered around Humboldt Bay (approximately 900 acres) with another 20 or so acres around the mouth of the Eel River. Salt marshes in the Humboldt Bay and Eel River estuaries have been reduced by 90% in the last hundred years, a trend that parallels salt marsh loss all along the west coast. On the North Coast the majority of the area that a hundred years ago was tidal marsh has since been converted to agricultural pastureland (Pickart 2001).
In addition to the direct loss of salt marsh habitat through diking, draining, and filling, this area's salt marshes have further been degraded by the invasion of an aggressive, non-native weed: dense-flowered cordgrass (Spartina densiflora). Unlike the salt marshes of the Central and South Coast which harbor California cordgrass (S. foliosa), the Humboldt Bay and Eel River estuaries originally had no cordgrass component (Pickart 2001). Dense-flowered cordgrass was most likely introduced in ship ballast in the mid 1800s during the lumber trade with Chile.
Dense-flowered cordgrass is capable of reproducing both vegetatively and by seed, and unlike most native salt marsh species, it does not go completely dormant during the winter months. Because of its year-round growth and relatively tall height and dense growth form, dense-flowered cordgrass has a competitive advantage over many of the native salt marsh species (Pickart 2001). It primarily inhabits the low to mid tidal elevations where it occurs in dense stands with common pickleweed (Salicornia virginica) (Sawyer & Keeler-Wolf 1995; USFWS 1998). Where openings in these stands occur other salt marsh species, including tufted hair grass (Deschampsia caespitosa), can also be found (Pickart 2001). Unfortunately, dense-flowered cordgrass can occur at higher tidal elevations as well, and it has been steadily increasing in these intact salt marsh areas (USFWS 1998; Pickart 2001).
Saltgrass (Distichilis spicata) is a common native salt marsh species that occurs at low to high tidal elevations. The only species of the genus in the state, saltgrass is widespread across California, the United States, and throughout southern Canada in salt marshes and moist alkaline areas. Like many other salt marsh species saltgrass has special adaptations for dealing with saline toxicity. In addition to C4 photosynthesis, which helps to reduce water loss, this species possesses specialized excretory glands that collect and concentrate salts, releasing them as brine to the outside of the plant body (Barbour et al. 1993). Other species often associated with saltgrass include pickleweed, jaumea (Jaumea carnosa), marsh rosemary (Limonium californicum), and arrow-grass (Triglochin maritima) (USFWS 1998).
Sicklegrass (Parapholis spp.) is another type of salt marsh grass occurring around Humboldt Bay. There are two species of sicklegrass in California, P. incurva and P. strigosa. Both are of European origin, and both occur along the North Coast. As with saltgrass, sicklegrass species also possess specialized glands for isolating and excreting salts.
A number of rare plant taxa (not necessarily of the Gramineae) occur in salt marsh communities of the North Coast. Dwarf alkali grass (Puccinellia pumila) is a rare salt marsh grass of limited distribution in California. It is known from only three occurrences in Humboldt and Mendocino Counties, but it is more common in Oregon, Washington, and northeastern North America (CNPS 2000; Hickman 1993). The Humboldt Bay owl's clover (Castilleja ambigua ssp. humboldtiensis) and the Point Reyes bird's beak (Cordylanthus maritimus ssp. palustris) are two rare hemiparasitic annuals of the snapdragon family endemic to the North Coast. Both are rare and endangered in California and elsewhere. Annual plants are rare in salt marshes because they generally lack the adaptations necessary for tolerating salinity (Barbour et al. 1993). Any discussion of salt marsh restoration must take into consideration these and other invaluable components of the ecologically-unique salt marsh community.
One relatively common native grass found in coastal prairies of the North Coast is Pacific reed grass (Calamagrostis nutkaensis). Ranging as far south as the San Francisco Bay area and as far north as Alaska, Pacific reed grass often is found growing in mesic to wet areas on beaches, dunes, and coastal woodlands. On the North Coast it is commonly associated with the coastal prairie-Sitka spruce forest interface.
Various other reed grass species also occur in the North Coast region, though they are not necessarily restricted to coastal prairie habitats. Bolander's reed grass (Calamagrostis bolanderi), endemic to the North Coast, is found on mesic woodland sites, especially in the Bishop pine-Redwood forest transition areas of Sonoma, Mendocino, and Humboldt Counties. It is listed by the California Native Plant Society (CNPS) as rare in California and elsewhere (see below). Leafy reed grass (C. foliosa), also endemic to the North Coast, is listed by the state as rare and by CNPS as a plant of limited distribution. The species has a number of occurrences on bluffs, cliffs, and coastal scrub in the King Range of southwestern Humboldt County. Thurber's reed grass (C. crassiglumis), listed by CNPS as rare in California but more common elsewhere, is known from fewer than ten occurrences in the state (CNPS 2000). It occurs in mesic coastal scrub and freshwater marshes and swamps. Finally, serpentine reed grass (C. ophitidis), true to its name, grows on serpentine substrates in Marin, Napa, Sonoma, and Lake Counties (CNPS 2000).
One other rare grass that occurs in mesic coastal prairies of the North Coast is vanilla grass (Hierochloe odorata). Listed by CNPS as rare in California (known from only three occurrences) but more common elsewhere, vanilla grass is known on the North Coast from only a single site near Crescent City. The next closest occurrence of the species is on Mt. Shasta at over 5,000 feet! Its presence in this mesic coastal prairie is somewhat of an anomaly. This particular coastal prairie, however, is indeed special it that it harbors several other rare taxa including the federally endangered western lily (Lilium occidentale), the marsh pea (Lathyrus palustris), great burnet (Sanguisorba officinalis), arctic star flower (Trientalis arctica), and marsh violet (Viola palustris).
The fog belt that envelopes the North Coast throughout the year has allowed for the predominance of redwood forest across the landscape. Typically dense with ferns, shrubs, and decaying woody debris, the redwood forest understory does not harbor a strong grass component. One species that is relatively common in the understory, however, is California sweet grass (Hierochloe occidentalis). Known for its showy flowers and sweet-smelling leaves, California sweet grass ranges as far south as southern California and as far north as Washington. Native Americans traditionally burned fresh sweet grass leaves as incense.
Other native redwood forest grass species that occur sporadically in the understory include onion grass (Melica spp.), crinkle-awn fescue (Festuca subuliflora), bearded fescue (F. subulata), and nodding trisetum (Trisetum cernuum). Mannagrasses (Glyceria spp.) can occasionally be found in mesic to wet partial openings or along watercourse margins. American mannagrass (Glyceria grandis), which occurs from the North Coast to British Columbia and also in the eastern United States, is listed by CNPS as rare in California but more common elsewhere. More commonly encountered in this region are fowl mannagrass (G. elata), western mannagrass (G. occidentalis), and weak mannagrass (Torreyochloa pallida var. pauciflora).
The beautiful semaphore grasses (Pleuropogon spp.) are special to this region because four out of the five species in the genus occur in temperate western North America (the fifth occurs in eastern Asia), and three are found along the North Coast. The rare North Coast semaphore grass (P. hooverianus) is endemic to the central and northern California coast, while the uncommon nodding semaphore grass (P. refractus) occurs as far north as British Columbia. The more common California semaphore grass (P. californicus) extends inland to the foothills of the Cascade and Sierra Nevada ranges.
Unfortunately, an overview of grasses of the redwood forest would not be complete without a mention of Pampas grass (Cortaderia jubata), a noxious weed along California's coast and outer ranges. One of the effects of timber management activities on the species composition of redwood forests is an increasing dominance of cut-over areas by wind-dispersed, invasive, non-native species. Pampas grass is an especially aggressive weed that is ubiquitous in clearcuts, along logging roads, and in various other disturbed habitats. The plants are pistillate only and produce fruit asexually (Hickman 1993). They form giant tufts of basal leaves with razor-sharp edges (the genus is named for the Argentinean term for `cutting'), and inflorescences can stand over seven meters tall. Pampas grass is often found growing with other invasive, wind-dispersed species such as thistles (Cirsium spp.), European annual grasses, and hairy cat's ear (Hypochaeris radicata).
Rare Grasses of the North Coast
Because grasses are so diverse and ubiquitous across the landscape, grass species, like all species in general, will inevitably be affected by land management practices, development, and habitat conversion---some species being more sensitive to impacts than others. The California Native Plant Society (CNPS) maintains an inventory of rare, threatened, and endangered vascular plants for the state, and 64 grass taxa are included in the latest edition (CNPS 2000). Each taxon is assigned a listing code, defined as follows:
CNPS List 1A: plants presumed extinct in California
CNPS List 1B: rare, threatened, or endangered in California and elsewhere
CNPS List 2: rare, threatened, or endangered in California, but more common elsewhere
CNPS List 3: plants about which more information is needed; a review list
CNPS List 4: plants of limited distribution; a watch list
In addition to the CNPS list, taxa are also rated according to their rarity (which addresses the extent of the plant, both in terms of numbers of individuals and the nature and extent of distribution), endangerment (which embodies the perception of the plant's vulnerability to extinction for any reason), and distribution (which focuses on the overall range of the plant) (CNPS 2000). This so-called R-E-D Code assigns a ranking of 1, 2, or 3 for each component; a higher number indicates greater concern. The scoring of each of these complementary elements independently for each listed taxon allows for a deeper understanding of a plant's rarity and endangerment throughout its range.
A total of 16 listed grass taxa are known to occur in the North Coast region (Table 1). Half of these have highly restricted occurrences, half are endemic to California, and several are endangered throughout their entire range (refer to CNPS 2000 for more details).
Table 1. Rare grass taxa of the North Coast (as far south as Sonoma Co.) as listed in the CNPS Inventory of Rare and Endangered Vascular Plants of California (6th edition, 2000).
*R-E-D Code system is summarized as follows (CNPS 2000):R (Rarity)
This article has presented an overview of some of the North Coast region's diverse and interesting grass taxa. A unique assemblage of native grasses occur in the varied and distinctive natural communities that characterize the region, many of which have been impacted and degraded due to development, non-native species (especially weedy grasses!), altered hydrology, grazing, trampling, and other disturbances. By working to protect and restore the remaining intact coastal and forest habitats of the region, ecological integrity and biological diversity on the North Coast will be sustained.
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California Department of Fish & Game. 2000. California's Natural Diversity Data Base RareFind 2 computer application. CDFG. Sacramento, CA.
California Native Plant Society. 2000. Inventory of rare and endangered vascular plants of California, 6th edition (electronic version). CNPS. Sacramento, CA.
Hickman, J. C. (ed.). 1993. The Jepson manual: higher plants of California. University of California Press. Berkeley, CA.
Pickart, A. 2001. Humboldt County's salt marshes, http://www.northcoast.com/~cnps/saltmars.htm
Sawyer, J. O. & T. Keeler-Wolf. 1995. A manual of California vegetation. CNPS. Sacramento, CA.
U.S. Fish & Wildlife Service. 1998. Vascular plants and vegetation types of the Lanphere Dunes Unit, Humboldt Bay National Wildlife Refuge. USFWS. Arcata, CA.Melissa Brooks
Last modified 05/24/01 13:24 EDT