2007 Annual Monitoring Report (pdf 16MB) - Bolsa Chica Lowlands ...

Bolsa Chica Lowlands Restoration Monitoring2007 Annual ReportDecaying/Transitional VegetationThis habitat was used to describe transitionalvegetation communities exhibiting theeffects of exposure to regular tidal influencefollowing long periods of freshwaterinfluence or intermittent inundation. Thisincluded the many dead eucalyptus trees thatring the Muted Pocket Marsh and presentlyprovide roosting and perching habitat for avariety of birds. These trees will eventuallydecay and begin to fall into the marsh. Thiscategory was also used to describe nearly allDecaying marsh vegetation at Rabbit Island.of Rabbit Island. Prior to the opening of theFTB to the ocean, Rabbit Island supported upland species at the highest elevations and was ringed bycoastal salt marsh. Following the introduction of tidal influence, which at extreme tide submergesmuch of Rabbit Island, both the upland and salt marsh vegetation began to die. The majority of RabbitIsland is now covered with the standing dead woody stalks of past marsh and upland vegetation. It isanticipated that coastal salt marsh will become established at the mid- to high salt marsh elevations andcordgrass (Spartina foliosa) and mudflats will dominate at the lower marsh elevations.Non-Native VegetationNon-native vegetation was mapped primarily on the eastern boundaries of the study area in associationwith various construction activities and staging areas, as well as residential areas that contributeescaped landscape plantings. Common species include: radish, black mustard, castor-bean (Ricinuscommunis), myoporum (Myoporum laetum), hottentot fig(Carpobrotus edulis), and tumbleweed (Amaranthus albus).Notably, there is little to no occurrence of the highlyinvasive non-natives giant reed (Arundo donax) or pampasgrass (Cortaderia selloana) within the study area.Non-native vegetation and urban/developed areasadjacent to Freeman Creek.The areas immediately adjacent to the levee roadsbordering the marshes often supported a narrow mix ofroadside weeds and a few native species such asgoldenbush (Isocoma menziesii). These areas were notcalled out as a distinct habitat, rather included in either thecoastal salt marsh they were mixed with or theurban/developed road, as appropriate.Salt PanneBroad areas in much of the coastal salt marsh are unvegetated salt panne, particularly in the seasonalpond and future full tidal areas. These areas were historically inundated by seawater management onthe subsided marsh plain. These areas, however, are currently inundated intermittently by freshwater.These low permeability areas collect water during rainy months and dry though evaporation asconditions warm during spring and summer months. This leaves hypersaline conditions that areinhospitable to most marsh plants. Although pickleweed has colonized much of the salt panne areas,the areas lowest in elevation that pool water for long periods, remain unvegetated.Merkel & Associates, Inc. 22