Patterns of nitrogenase activity (acetylene reduction) associated with standing, decaying shoots of Spartina alterniflora

Abstract

Samples of standing-dead cordgrass have been reported to yield consistently high rates of nitrogenase activity (as acetylene [C2H2] reduction) per unit mass of sample (up to about 2 μmol ethylene [C2H4]·g−1 dry mass·day−1). We measured rates of C2H2 reduction over a range of conditions during the decomposition of standing cordgrass shoots. The degree to which standing, decaying leaves supported C2H2 reduction was correlated with the degree of coverage of the leaves by clay films (r2 = 0·41, P 40%) had rates of 102–104 nmol C2H2 produced·g−1 organic mass·day−1, whereas decaying leaves higher up the shoots with little or no clay coverage had rates