Since its introduction to North America, Lythrum salicaria (L.) (purple loosestrife) has become invasive in marshy and riparian habitats. We compared gas-exchange responses to external CO2 partial pressure and light, as well as related leaf structural and biochemical characteristics, of L. salicaria with those of co-occurring native Asclepias syriaca (common milkweed) and Solidago graminifolia (lance-leaved goldenrod) along a pond bank in the Black Rock Forest, Cornwall, New York, USA to examine if the invasive success of L. salicaria may be influenced by robust leaf gas-exchange characteristics, including relatively high rates of photosynthesis and low rates of respiration, compared with those of less successful co-occurring native plant species. Neither the mean rate of net photosynthesis measured at ambient CO2 and saturating photon flux density (A) nor the mean dark respiration rate (R-D) differed significantly between L. salicaria and either of the native species, while both the mean maximum rate of photosynthesis at saturating CO2 concentration and photon flux density (A(max)) and the mean rate of respiration measured in light (R-L) were significantly higher in L. salicaria than A. syriaca, but no different between L. salicaria and S. graminifolia. Likewise, photosynthetic nitrogen-use efficiency was greater in L. salicaria than A. syriaca only, while photo synthetic water-use efficiency was significantly less in both L. salicaria and S. graminifolia than in A. syriaca. Despite limited interspecific differences in leaf photosynthesis, respiration, and resource-use efficiency, particularly between L. salicaria and S. grainin folio, we found that L. salicaria assimilated 208% more carbon per unit of energy invested in leaf biomass than either of the co-occurring native species, suggesting that increased photosynthetic energy-use efficiency may influence its observed invasive success.
814HNTimes Cited:10Cited References Count:48