A survey of nitrogen fixation (acetylene reduction) associated with Typha in Minnesota

In 20 cattail stands sampled in 1985, Typha angustifolia showed a tendency for lower acetylene-reduction activity per ramet, with an average of 2.9μmol.ramet^-1.d^-1, than T. latifolia and T. × glauca, with averages of 6.5 and 7.1μmol.ramet^-1.d^-1, respectively. Regression analysis showed no significant differences in these values due to the variability within as well as between stands, and fixation rates were uncorrelated with the pH, soil percent carbon, and soil moisture of the study stands. In 1986, in situ assays of soil-root cores of ramets from adjacent monospecific stands produced average acetylene-reduction rate of 1.4 for T. angustifolia and 1.8μmol.ramet^-1.d^-1 for T. latifolia, with a substantial reduction in variability within stands over the 1985 data. Typha may receive as little as 1-2% of their annual N requirement from N-fixation. -from Authors