Net photosynthetic rate (<i>P</i>n), stomatal conductance (<i>G</i>s) and relative coverage (mean ± SE) of <i>Leymus chinensis</i> and <i>Phragmites australis</i> measured in June of 2006, 2007, 2008 and 2009.

Measurements were performed on the upper most fully expanded leaves from 9.00 to 11.00 a.m. Different letters indicate significant differences (P<0.05) among treatments with capital and small letters indicating differences between N and warming treatments, respectively. C = control; W = warming; N = N addition; WN = combined warming and N addition.