TML> Rickey, Marcia* and Roger Anderson. Phragmites australis is an invasive grass that has dramatically increased its distribution and abundance within its geographic range in the past fifty years. Sequence data show that Phragmites native haplotypes “E” and “S” and invasive haplotype “M” exist in North America. Three Illinois type M Phragmites sites and populations were characterized by soil analysis and photosynthetic measurements in this study: Banner, Lincoln, and Herrin. It was hypothesized that there will be differences in soil variables among sites and differences in maximum photosynthetic rates (PMAX) rates among populations. MANOVA yielded significant results (Wilks’ Lambda, F=5.67, p>F=0.0006) and univariate ANOVAs indicated significant differences among sites for total nitrogen, nitrate-nitrogen, organic matter, potassium, magnesium, and phosphorus. The Ryan-Einot-Gabriel-Welsch (REGW) multiple range test revealed that Banner Marsh was significantly lower than Lincoln and Herrin for log K, P, SqRt total N, and log NO3-N. Photosynthetic light response curves and PMAX, and light saturation values were determined for plants from the three populations. Plants had maximum photosynthetic rates of about 16 µmol CO2 m-2s-1 and achieved light saturation between 1200-1400 µmol m-2s-1 PPFD (photosynthetically active photon flux density). ANOVA revealed significant differences in PMAX rates among sites (F=38.14, p<0.0001) and that Lincoln had the highest mean PMAX of 20.88.

Key words: photosynthesis, Phragmites australis, soil analysis