THE VEGETATION OF BALLONA Robert J. Gustafson r OM THE VEGETATION OF BALLONA page Introduction and methodology 1 Wetlands definitions 2 eta Vegetation types 4 Estuarine habitats 4 Pickleweed saltmarsh 4 Mudflats and saltflats 5 OM Freshwater habitats 6 Willow community 6 Freshwater marsh 6 Terrestrial habitats 7 Coastal dune 7 Coastal scrub 7 Transitional pickleweed and salt pan 8 Coyote brush and pampas grass 8 Agricultural areas and weedy fields 8 SO Comments on plant species at Ballona 9 Unit 1 10 1St Unit 2 12 Unit 3 14 Plant species list 17 Literature cited 28 Figures 30 en Bo-1 1.1 The Vegetation of Ballona Robert J. Gustafson aso INTRODUCTION AND METHODOLOGY The vegetation of the Ballona wetlands has been carefully mapped and me discussed in previous reports (Envicom, Army Corps of Engineers, and UCLA). Apart from the plant species list prepared by Envicom and a partial list by Judith Clark for the UCLA report, an actual plant inventory had not been thoroughly undertaken with voucher specimens deposited into a credited institution. The present investigator is a taxonomist, not an ecologist, and it has been his primary purpose to collate a list of plant species over a one-year period beginning in July 1980 through August 1981. About 75 to 100 hours were spent walking over the study units on approximately 15 separate field trips. All the plants collected are deposited in the herbarium of the Natural History Museum, Los Angeles County. In addition, mo each herbarium sheet has a map of the study areas with an indication of the proximate locality where the plant was collected. No rare and endangered species were recorded from the sites, but some plants not previously found in Southern California either as escapes or adventives were discovered. In cases of uncertainty in identification, plants were sent to Tom Fuller and Doug Barbe at the Department of Food & Agriculture, Sacramento, who specialize in introduced weeds. No mapping or transects were undertaken by this investigator, although distribution of plant 4ok int Bo-2 species in the various parcels was carefully noted. WETLANDS DEFINITIONS The U. S. Fish and Wildlife Service defines wetlands as follows: "...land where the water table is at, near or above the land surface lona enough to promote the formation of hydric soils or to support the growth of hydrophytes. In certain types of wetlands, vegetation is lacking and soils are poorly developed or absent as a result of freouent and drastic fluctuations of surface-water levels, wave action, water flow, turbidity or high concentration of salts or other substances in the water or substrate. Such wetlands can be recognized by the presence of surface water or saturated substrate at some time during each year and their location within adjacent to vegetated wetlands MEI or deep-water habitats." Three parcels of land (designated as Units 1, 2 & 3, see maps) were Ong carefully surveyed by the museum team for over a one-year period. As a result, the breakdown of wetlands within each of these parcels is defined as follows. Unit 1: approximately 72 acres bounded by the Ballona Channel MIMI on the west, Culver Boulevard on the east, the dune community on the south and the Gas Co. entrance on the north. Unit 2: west of the Gas Co. road, approximately 55 acres bounded by the bluffs to the south, Culver Boulevard to the west; east of the Gas Co. road on property which is bounded by the bluffs on the south, Jefferson Boulevard on the north and Lincoln Boulevard on the east area freshwater marsh 2-3 acres in size just east of the Gas Co. facility, and a riparian community about 4 feet on each side of the Centinela Creek drainage ditch along its entire length. In the western part of the occasionally-flooded agricultural area degraded Salicornia is found. Unit 3 is the dredge spoils from the construction of the Marina in 1961-62. This 139-acre parcel contains approximately 62 acres of dry pickleweed (transitional) Bo-3 habitat. The presence of Salicornia has been used as an indicator of wetlands, but the existence of Salicornia, by itself, does not indicate conclusively that this area is a wetland biologically. Salicornia on this site is poor in quality, especially by comparison to that found in Units 1 and 2 which are subject to tidal flow. The pickleweed community of the spoils area is more or less confined to the central, lower portions of the fill which contain the salt pans. Whether or not hydric soils are present here seems to be a debatable point: the Shapiro report for the Corps maintaining there are, while the Fruit Growers Laboratory, Inc., findings indicate the exact opposite. Only further analyses will resolve the issue. Other factors that may play a IME part in the presence of Salicornia on this site are its hydrophytic as well as halophytic nature, the presence of sea water intrusion and capillary action which could provide sufficient moisture to maintain the community, or a perched water table. It would appear that the successional scrub community that is forming on the higher portions of the spoils is slowly advancing, probably because OE the winter rainfall has been leaching out the salts and washing them into the central depressions over the past 20 years. That the Salicornia IP persists is certainly an indication of its halophytic nature, although it has never been proved to be an obligate halophyte. Salt flats may be an important aspect of a salt marsh ecosystem, but this is not the case IN here because the spoils do not contain a salt marsh habitat, and there is no tidal influx. However, the land has value as open space and the opportunity to watch the development of an upland scrub community. OCCASIONALLY FLOODED ARGICULTURAL AREA In addition to the wetlands areas, there are 15 to 20 acres of occasionally flooded agricultural lands located east of the Gas Co. road in Unit 2 (see map). Bo-4 VEGETATION TYPES Three designated areas have been extensively surveyed over a one-year period and the results have been plotted on three maps (see Figures Bo-1-3 respectively). Because the boundaries between the plant communities are, or have been subject to topography, urban disturbance or soil type, one does not necessarily find a nice gradational pattern between them. The maps (legend adapted from Envicom report) indicate the major grouping of plants within each of the study areas. These maps correspond closely to the overall findings of the Shapiro report. Estuarine Habitats 1. Pickleweed Saltmarsh (Fig. 4) Pickleweed (Salicornia) is the dominant plant of this community. Two species occur at Ballona with S. virginica being the most abundant and found in all three units. S. subterminalis is locally common only in Unit 1. Salicornia is the most widespread halophyte in California saltmarshes. It forms a low-growing, dense stand south of the Ballona Channel in Unit 1, while in Unit 2 it is most prevalent west of the Gas Co. road. East of the road in the Agricultural area, Salicornia is present in limited areas where winter ponding occurs. Agricultural practices in previous years have resulted in the area being disced during the early summer months. The plants on the dredge spoils of Unit 3 are centrally located bordering the salt pans. Within the pickleweed marsh proper are areas that are or have been invaded by aggressive weedy species. Iceplant (Carpobrotus edulis) has invaded the marsh in the southern part of Units 1 & 2 where it forms an almost impenetrable ground cover. Saltgrass (Distichlis spicata) is common in these transitional areas, especially in the southwestern section of Unit 1 where the marsh abuts against the sand dune community. It is frequent in Unit 2 throughout the pickleweed community and also is present in some upland areas, especially highly disturbed situations. Po Bo-5 Sicklegrass (Parapholis incurva), an introduced European species naturalized in California saltmarshes, is relatively common in the central section of Unit 1 (also in the eastern half of Unit 2), especially along the drying edges of the pickleweed conHunity. Other aggressive weeds such as IMP Melilotus, Conyza, Rumex, Beta, Picris and Atriplex can also be found here. Introduced weedy species comprise approx. 15% of the total plant cover On of the pickleweed communities and are most abundant on the berms or along UN paths through the marsh. Since the Ballona saltmarsh lacks a low and middle marsh flora, the pickleweed occurrence is topographically lower than in other Southern California saltmarshes which have been subject to less disturbance. Many saltmarsh species are not found at Ballona,due perhaps to the restricted water-flow between the marsh proper and the channel. Although the pickleweed marsh at Ballona is considered a high marsh, several species (Monanthochloe littoralis, Limonium californicum, etc.) usually characteristic of this situation are absent. Before the advent of the flood control channel during the 1930 1 gm developeds, it periodically which restricted the flow of water to the marsh. is As it now stands, several factors such as stagnation, salinity, temperature possi fluctuations,ble etc., have kept the marsh at a low-level species density. tha t •• 2.a Mudflats and Saltflats (Fig. 5) nat - The vegetation of these areas is practically non-existent except for ura thel presence of green algae which become abundant during the spring-summer ba months.rr Since these areas are slightly lower than the pickleweed ie communities, the salt crusts associated with them undoubtedly have a r strongc influence in limiting the vegetation. A thin layer of water often o persistsu on these flats depending on the rainfall from the previous winter- gin springl months.