Appendix B. A canonical correspondence analysis (CCA) multivariate ordination diagram relating plant community structure to environmental variables in the BMR salt marsh.
FIG. B1. Canonical correspondence analysis ordination diagram relating plant community structure to environmental variables along the intertidal gradient in the Bodega Marine Reserve salt marsh. Symbols indicate plant species (+), releves , and environmental variables (arrows), first axis is horizontal and second axis is vertical. Four letter species code abbreviations are ATCA = Atriplex californicus, ATPR = Atriplex prostrata; COMA = Cordylanthus maritimus ssp. palustris; CUSA = Cuscuta salina; DISP= Distichlis spicata; FRSA = Frankenia salina; JACA= Jaumea carnosa; LICA = Limonium californicum; PAIN = Parapholis incurva; PLMA = Plantago maritima, POMA = Polygonum marinense PUNU = Puccinellia nutkaensis ; SAPA = Sarcocornia pacifica; ISCE = Isolepis cernuus; BOMA = Bolboschoenus maritimus; SCPU = Schoenoplectus pungens; SPMA = Spergularia macrotheca; TRCO = Triglochin concinna; and TRMA = Triglochin maritima. Environmental variables are BIOMASS = above ground plant biomass, CANOPY = maximum plant canopy height, C = total soil carbon, N = total soil nitrogen; LOI = soil organic matter (loss on ignition), SBD = soil bulk density, SSC = soil saturated conductivity, SWC = soil water content, SF = below canopy sunfleck fraction; and PAR = below canopy photosynthetically active radiation. See Grewell (2004) for analytical methods. Soil phosphorus was measured but is not shown as it was eliminated during forward selection of significant variables (P< 0.5).The relationship between plant community and environmental data was highly significant (F = 8.134, P = 0.002, Monte Carlo test), and the first three canonical axes explained 38.6%, 29.5%, and 15.2% response of the variance in plant species abundance distribution. Cuscuta salina is restricted to the high intertidal zone that is regularly, but infrequently inundated by tides, and has the highest levels of incoming PAR and sediment salinity, and the lowest levels of total sediment nitrogen and carbon (Grewell 2004).
Grewell, B. J. 2004. Species diversity in northern California salt marshes: functional significance of parasitic plant interactions. Ph.D. Dissertation. Graduate Group in Ecology, University of California, Davis, California, USA.