Photosynthesis, nitrogen allocation and specific leaf area in invasive Eupatorium adenophorum and native Eupatorium japonicum grown at different irradiances

Feng, Yu-Long

PHYSIOLOGIA PLANTARUM

2008

133

2

Feng, YL

The mechanisms underlying biological invasions are still not well elucidated. In this study, ecophysiological traits of invasive Eupatorium adenophorum and native E. japonicum were compared at 10 irradiances in field. I hypothesized that the invader may allocate a higher fraction of leaf nitrogen (N) to photosynthesis and have higher light-saturated photosynthetic rate (P-max) and specific leaf area (SLA) than E. japonicum. The invader had a significantly higher ability to acclimate to high irradiance than E. japonicum, while it showed a similar shade-tolerant ability. The invader indeed allocated a higher fraction of leaf N to photosynthesis than E. japonicum, which, with its high leaf N content (N-A), resulted in a higher N content in photosynthesis (N-P), contributing to its higher biochemical capacity for photosynthesis and P-max. However, the invader had a significantly lower SLA than E. japonicum, contributing to its higher P-max but increasing its area-based leaf construction cost. The abilities to acclimate to a wider range of irradiance and to allocate a higher fraction of leaf N to photosynthesis, and the higher P-max, N-A, N-P and leaf area ratio may contribute to the invasion of the invader. High SLA is not always necessary for invasive species.