2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
Decaying/Transitional Vegetation
This habitat was used to describe transitional vegetation communities exhibiting the effects of
exposure to or inundation by regular tidal influence following long periods of freshwater influence or
intermittent inundation. This included rampikes of dead eucalyptus and Myoporum trees that ring the
Muted Pocket Marsh and presently provide roosting and perching habitat for a variety of birds. These
trees will eventually decay and begin to fall into the marsh. This category was also used to describe
large areas of Rabbit Island. Prior to the opening of the FTB to the ocean, Rabbit Island supported
mostly non-native upland species at the highest elevations and was ringed by coastal salt marsh.
Following the introduction of tidal influence, which at extreme tide submerges much of Rabbit Island,
both the upland and salt marsh vegetation began to die. Much of Rabbit Island is now covered with the
standing dead woody stalks of past marsh and upland vegetation, including broad expanses of dead
hottentot fig (Carpobrotus edulis). It is anticipated that as the decaying vegetation decomposes,
coastal salt marsh will gradually become established at the mid- to high salt marsh elevations and
cordgrass and mudflats will dominate the lower marsh elevations.
Decaying marsh and hottentot fig on Rabbit Island (left/center), dead salt marsh transitioning to mud flat following inundation of the west MTB (right).
Small losses to salt marsh in the MTBs and Seasonal Ponds were mapped as decaying vegetation as
well, due to prolonged inundation by tidal waters or seasonal freshwater ponding. This process had
only begun in the MTBs and is expected to results in greater losses of marsh in the coming years as the
MTBs are all opened to tidal influence.
Non-Native Vegetation
Non-native vegetation was mapped primarily on the eastern boundaries of the study area in association
with various oil filed operations and staging areas, as well as residential areas that contribute escaped
landscape plantings. Common species include: radish, black mustard, castor-bean (Ricinus communis),
myoporum (Myoporum laetum), hottentot fig, and tumbleweed (Amaranthus albus). Notably, there is
little to no occurrence of the highly invasive non-natives giant reed (Arundo donax) or pampas grass
(Cortaderia selloana) within the study area. By May 2008 non-native vegetation, primarily hottentot
fig and slender-leaved iceplant (Mesembryanthemum nodiflorum), had begun to colonize the created
nest sites. Only areas that were infested to a high enough degree as to preclude nesting were mapped
as non-native vegetation, however there was a regular scattering of these and some native species on
the surface of all three nest sites.
The areas immediately adjacent to the roads bordering the marshes often supported a narrow mix of
roadside weeds and a few native species such as goldenbush (Isocoma menziesii). Unless these weed
bands were more than about 3 m wide and monotypically non-native, these roadside areas were not
called out as a distinct habitat, rather included in either the coastal salt marsh they were mixed with or
the urban/developed road, as appropriate.
Merkel & Associates, Inc. 27