Search for: All records

PREMISEBiological invasions increasingly threaten native biodiversity and ecosystem services. One notable example is the common reed,Phragmites australis, which aggressively invades North American salt marshes. Elevated atmospheric CO₂and nitrogen pollution enhance its growth and facilitate invasion becauseP. australisresponds more strongly to these enrichments than do native species. We investigated how modifications to stomatal features contribute to strong photosynthetic responses to CO₂and nitrogen enrichment inP. australisby evaluating stomatal shifts under experimental conditions and relating them to maximal stomatal conductance (g_wmax) and photosynthetic rates. METHODSPlants were grownin situin open‐top chambers under ambient and elevated atmospheric CO₂(eCO₂) and porewater nitrogen (N_enr) in a Chesapeake Bay tidal marsh. We measured light‐saturated carbon assimilation rates (A_sat) and stomatal characteristics, from which we calculatedg_wmaxand determined whether CO₂and N_enraltered the relationship betweeng_wmaxandA_sat. RESULTSeCO₂and N_enrenhanced bothg_wmaxandA_sat, but to differing degrees;g_wmaxwas more strongly influenced by N_enrthrough increases in stomatal density whileA_satwas more strongly stimulated by eCO₂. There was a positive relationship betweeng_wmaxandA_satthat was not modified by eCO₂or N_enr, individually or in combination. CONCLUSIONSChanges in stomatal features co‐occur with previously described responses ofP. australisto eCO₂and N_enr. Complementary responses of stomatal length and density to these global change factors may facilitate greater stomatal conductance and carbon gain, contributing to the invasiveness of the introduced lineage.