Захист прибережних екосистем на муніципальному пляжі Морро Странд в окрузі Сан-Луїс Обіспо, Каліфорнія
Morro Strand State Beach — viewed from the Back Dunes with Morro Rock, located on Estero Bay in San Luis Obispo County, California. Taken after the Snowy Plover habitat protection fence was taken down for the season, in October 2011. Information about the area's natural history, from: www.slostateparks.com/general_park_info/resources/MSSB_Biological_Inventory.pdf Morro Strand State Beach (MSSB) comprises approximately 159.15 acres between the north parcel (Old Creek site) and south parcel (formerly called Atascadero State Beach) as well as an additional 23 acres which is to be transferred to State Parks from the Cloisters development. Morro Strand State Beach−MSSB provides a valuable remnant of the strand, dune, and dune wetland communities that were once common along our coast. This area is characterized by a Mediterranean climate which yields dry summers and wet winters. MSSB is located along the immediate coast and stretches from the town of Morro Bay, north towards the town of Cayucos. It is backed, on the eastern side, by the foothills of the Santa Lucia Range and a stretch of homes in the lower foothills along both the western and the eastern side of Highway 1. There are direct maritime influences such as thick coastal fog, constant wind and salt spray and blowing sand, as well as onshore impacts such as stormwater run-off which impact this property. Common communities at MSSB include: beach strand fore and stabilized dunes coastal dune scrub dune wetlands and swales riparian corridors anthropogenic (human influenced). These shoreline communities provide habitat for a plethora of species including, but not limited to: foraging seabirds, nesting and foraging shorebirds, sensitive plants, small mammals, and many invertebrates. History Coastal habitats have been systematically obliterated in California, particularly south of Point Conception, largely due to development. Where these habitats have been able to persist, they are largely dominated by invasive plants such as Ammophila arenaria (European beachgrass), Carpobrotus chilensis (Chilean iceplant), Carpobrotus edulis (hottentot fig), and Cakile maritima (sea rocket), and are often impacted by human activities such as off road vehicles, dogs, and various other activities.... A large mitigation pond was built near the Cloisters housing development around 2000 to offset any damage to the natural habitat caused by the building of the development itself and to control run-off. This pond fills with storm water run-off from the urban areas upslope as well as from rain water. It is not only filling with Tules which support Great-tailed Grackles, but it regularly overflows and drains to the ocean through the stabilized dunes, the dune swales and the foredunes introducing non-native species such as Gambusia sp., Crayfish and Carp to the ephemeral ponds.” Terrestrial Plant Communities Strand While not vegetated by plants, the Strand is an important community that provides habitat and food for many species. The Strand is the area of the beach between the supralittoral zone and the foredunes. It is characterized by salt spray, fog water inundation, high winds, blowing sand, and accumulations of uprooted marine algae, driftwood and other debris. Common wrack-line seaweeds on the Strand include: Macrocystis spp. (giant kelps), Nerocystis spp. (bull kelps), Fucus spp. (rock kelps), Egregia spp. (feather boas), and Uva spp. (sea lettuce). The mounds of washed-up seaweed provide food and habitat for many invertebrate species and food for vertebrates such as birds. Above the high tide line the sand begins to accumulate at the foredunes. Coastal Dune Communities According to Orme (1990), coastal dune creation and mobility are favored by abundant beach sand and onshore winds above the threshold velocity for sand entrainment and the primary stabilizing factor is the effectiveness of sand-binding vegetation. MSSB is part of the Morro Dune Complex which stretches from Montana de Oro State Park (MDO) to the south and north to Cayucos and Villa Creek. MSSB is, however, significantly less diverse than the dune communities found at MDO, presumably from direct human impacts and the spread of Ammophila arenaria. Native species not found at MSSB but present at MDO include: Leymus mollis (native dunegrass), Eriastrum densiflora (woolly gilia), Dithyrea maritima (beach spectacle pod), Malacothrix incana (dune-delion) and Dudleya caespitosa (dudleya). Many of these native species are being re-introduced as part of our restoration efforts. Fore/Pioneer Dunes The fore or pioneer dunes are those dunes located nearest to the shoreline. They are characterized by a high rate of sand movement which exceeds the rate of colonization by vegetation. This region of the sand dunes is subject to extremely harsh environmental factors which greatly reduces plant life and diversity as well as provides uniquely adapted assemblages of plants. Such conditions include: desiccation from wind and salt spray, salt and sand abrasion, high reflectivity and surface temperatures, constant fog, fluctuating tides, high salt content in the soils, low soil fertility and water holding capacity, and constant burial, excavation, and re-burial of root systems. The plants that grow on the foredunes are often called dune stabilizers and are very tolerant of the above mentioned environmental pressures. Foredune plant species are often prostrate or creeping along the soil surface, have small succulent leaves with pubescence, are light in color, and have a small surface to volume ratio. They also typically have a large tap root, a complex shallow or surface root system and generally root at the nodes. Common native dune stabilizers at MSSB include: Ambrosia chamissonis (beach bursage), Abronia latifolia (yellow sand-verbena), Abronia maritima (beach sandverbena), Abronia umbellata (purple sand-verbena), Camissonia cheiranthifolia (dune evening-primrose), Artiplex leucophylla (beach salt-wort), and Croton californicus (croton). Common non-native dune stabilizers at MSSB include: Cakile maritima (sea-rocket), Carpobrotus chilensis (sea-fig), Carpobrotus edulis (hottentot-fig), and Ammophila arenaria (European beach grass). The non-native species that invade the foredunes are of particular concern as they readily displace the few native species that are capable of living in this harsh environment. Stabilized Dunes Stabilized or back dunes occur inland of the pioneer dunes at MSSB where there is enough vegetation present to reduce or stop the rate of air movement along the sand surface. Stabilized dunes are considered to be older dune communities and are classified by their increase in plant species diversity and composition. These species are, however, less tolerant of the harsh environmental variables that affect species in the pioneer dunes and are therefore restricted to the more sheltered regions of the dune ecosystem. There are many different plant communities that occur on stabilized dunes. Those present at MSSB include: coastal dune scrub, coastal dune swale, Riparian, and Ammophila arenaria dominated dunes. Coastal Dune Scrub The primary native plant community on the stabilized dunes at MSSB is coastal dune scrub. Successionally older than the pioneer dunes, it is largely dominated by shrubby species although forbs are present. Coastal dune scrub has much more stable and fertile soils than the pioneer dunes, with greater organic matter content and water holding capacity and a much lower salt content. Species composition in coastal dune scrub communities differs from other coastal scrub communities; these differences are, in a large part, attributed to edaphic factors and proximity to the shoreline. There are a few plants that share co-dominance throughout the coastal dune scrub although dominance of these species shifts from north to south along the dune system. The most common shrub species in this community include: Lupinus chamissonis (silver dune lupine), Baccharis pilularis (coyote brush), Artemisia californica (California sage-brush), Eriogonum parvifolium (coastal buckwheat), Ericameria ericoides (mock heather), Hazardia squarrosa (sawtoothed goldenbush), and Eriophyllum staechadifolium (coastal golden yarrow). Common sub-shrubs and forbs include: Lotus scoparius (Deerweed), Erigeron blochmaniae (Blochman’s leaf-daisy), Heliotropium curassavicum (heliotrope), Lessingia filaginifolia (California aster), Croton californicus (croton), Achillea millifolium (common yarrow), and Horkelia cuneata (horkelia). Coastal Dune Wetlands Coastal dune wetlands comprise a large percentage of the stabilized dunes at MSSB. They occur in low-laying areas and depressions between the back dunes where the surface of the dunes are at or near the water table. Many of these depressions are created by wind erosion of the dunes and filling in of old stream channels that meandered through the dune system. While many of the species in these areas are phreatophytes, having high moisture requirements and roots that reach the water table, the coastal dune wetlands are at the dry end of wetland communities and are intermediate in moisture content. Common plant communities in the dune wetlands of MSSB include: fresh water coastal dune swales, alkaline coastal dune swales and isolated pockets of riparian zones. Fresh Water Coastal Dune Swale:The coastal dune swales at MSSB occur in long continuous expanses that run north to south between stabilized dune chains. At MSSB they are typically dominated by fresh water species such as Juncus acutus (spiny rush), Juncus phaeocephalus (brown-headed rush), Juncus patens (spreading rush), Scirpus americanus (bulrush), Scirpus pungens (common three-square), Carex obnupta (sedge), Carex praegracilis (sedge), Potentilla anserina (coastal silverleaf), Baccharis douglasii (marsh baccharis), and various other species of Scirpus, Carex and Juncus. While most of the wetlands are ephemeral, there are a few that seem to persist year-round. Alkaline Coastal Dune Swale:Alkali coastal dune swales occur in the stabilized dunes of MSSB as discontinuous pockets. They have much a higher soil salt content and are characterized by species such as Salicornia virginica (pickleweed), Jaumea carnosa (fleshy jaumea), Frankenia salina (alkali heath), Atriplex leucophylla (beach saltwort), and Atriplex triangularis (spearscale). While they are a minor component of the dune system they often occur on the coastal fringes of the large fresh water swales and are concentrated at the north end of MSSB south. Riparian:There are very few riparian areas at MSSB. At the north parcel, Old Creek forms a riparian area that is dominated by Salix lasieolepis (arroyo willow). Other common species there include Rubus ursinus (California wild blackberry), Scirpus pungens (common three-square), and Carex spp. (sedges). There are three main creeks that flow into the southern parcel of the park; an un-named creek that flows from Del Mar Park (at the north end of the southern parcel), Alva Paul Creek at the southern end of the campground which provides bird foraging and bathing habitat, and an un-named creek that runs between the Cloisters development and Morro Bay High School which was created by channelization. A forth, seasonal creek in the campground is intermittent, but often pools, forming a small lagoon. If present, the dominant canopy cover is Salix lasiolepis (arroyo willow). Populus fremontii (cottonwood) is also present at the MSSB southern property but is uncommon. The shrub component is generally absent and the understory forbs are predominately Stachys bullata, Potentilla anserina, and various Juncus, Carex, and Scirpus species. Seral Dune Communities There are large patches of seral dunes that run in discontinuous bands the length of Morro Strand State Beach. Many of these areas are a result of exotic plant removal projects. Where Carpobrotus spp. and Ammophila arenaria have been removed, successional natives such as Heterotheca grandiflora are coming in as volunteers as well as native dune stabilizers including Ambrosia chamissonis and Camissonia cheiranthifolia, and Lotus scoparius at the burn plot. Many of these areas are successional to foredune communities while the inland slopes are successional to coastal dune scrub. Another area of succession is located in and around the arson fire acreage and will result in various stages of dune community succession where many common native species are already recolonizing. Also, just north of the boardwalk, there is a large, open area with compacted alkaline soils. Dwarfed Salix lasioelepis occurs in patches and club mosses and ground lichens cover the soil while Heterothecea grandifolia is the dominant forb covering most of the area. There was clearly a disturbance here, presumable from a time when vehicles could access the dunes before the Cloisters development. Anthropogenic Large sections of dunes have been colonized by Ammophila arenaria (European beach grass), forming a monoculture where it occurs, displacing virtually all native plant species. An Ammophila removal/native restoration plan is in progress; see the section on exotic species for more information. Other ruderal species include Raphinus sativa, Erharta calcynia, Melilotus alba, Cortedaria jubata, and Lobularia maritima (See Exotic section below). A main source for these non-native species is the housing developments that border MSSB north and south parcels and the empty lots between them.