Surveying the Ballona Wetlands Marsh Habitat to measure non-native plants

Invasive species have become a pernicious ecological threat in degraded wetland ecosystems.  They can competitively exclude native plants for resources, causing widespread biotic homogenization, altered nutrient cycles, and lowered biodiversity.  The objective of this investigation was to assess the percent of native and invasive plant species diversity across lower and upper salt-marsh habitats at the Ballona Wetlands, and to characterize some chemical and physical parameters that could control differences in plant diversity.  The percent cover of plant species was determined along four 30-meter transects; two transects were positioned in the low marsh areas adjacent tidal channels and inundated by water during periods of high tide, and two in the upper marsh areas seldom wetted by tidal flows.  Along each transect plants were surveyed in five randomly placed 1 m² quadrates.  Three soil samples were collected from each transect and tested for salinity (ppt), percent organic matter, and grain size (%clay, % silt, % sand).  Preliminary results indicated that no non-native plants occurred in the surveyed areas.  Soils comprised mostly fine sediments with percent silts and clays usually ranging from 46.8% to 90.87%.  Organic matter content varied, ranging from 2.3% to 30.46% while soil salinity was quite variable, ranging from 15 to 88 ppt.  Future work will census the plant assemblage in wetland areas of slightly higher elevation where non-native species become abundant, and link soil characteristics to plant diversity through multivariate analytic techniques.