Construction cost and invasive potential: comparing Lythrum salicaria (Lythraceae) with co-occurring native species along pond banks

Lythrum salicaria (purple loosestrife) is a nonindigenous invasive species characterized by prolific growth and abundance in marshy and riparian habitats across North America. Given its invasive success, we hypothesized this species may require less energy and/or use energy more efficiently for biomass construction than co-occurring noninvasive plant species. We measured leaf construction cost (CC), leaf mass per unit area (LMA), and leaf organic nitrogen and carbon content of L. salicaria and the five most abundant co-occurring species, Parthenocissus quinquefolia, Erigeron philadelphicus, Asclepias syriaca, Spiraea latifolia, and Solidago graminifolia, along dammed ponds in the Black Rock Forest, Cornwall, New York, USA. Lythrum salicaria, which was highly abundant (2.52 individuals/m2), exhibited significantly lower area-based leaf CC (44.47 ± 4.24 g glucose/m2 leaf) than relatively less abundant species, suggesting energetics may influence its invasive success. Conversely, least abundant Solidago graminifolia (0.67 individuals/m2) exhibited the significantly highest leaf CC per unit leaf area (141.87 ± 39.21 g glucose/m2 leaf). Overall, a negative correlation between species abundance and area-based leaf CC (r2 = 0.73) indicated low energy requirements and/or high energy efficiency may influence relative abundance in the plant species studied. As it correlates with species abundance in this study, CC may be a useful tool for evaluating invasive potential.