Variation Among Genotypes and Source Habitats in Growth and Fecundity of the Wetland Invasive Plant Phalaris arundinacea L

The spread of invasive wetland plants has resulted in a number of negative impacts to wetland habitats including reductions in biodiversity, displacement of native plants, and altered water flow. Phalaris arundinacea L. (Reed canarygrass) is a highly competitive invasive plant in North American wetlands. While research has focused on growth characteristics and competitive ability of P. arundinacea in wetland habitats, little is known about how its growth in upland conditions differs from that in wetlands. To characterize differences in growth between upland and wetland habitats, we conducted a 13-month field experiment of unconstrained growth of P. arundinacea in upland and wetland conditions. A suite of traits was measured in genotypes collected from upland and wetland habitats. Although P. arundinacea most often occurs in wetlands, there was significantly higher growth and fecundity in the dry soil treatment. All of the growth traits measured varied among genotypes, a few varied between the habitats of origin, and significant interactions were found between habitat of origin and soil moisture treatment for several traits. The significant genetic variation observed suggests that there is potential for local adaptation to upland habitats. The higher growth and fecundity in upland conditions highlights the need for additional research to investigate P. arundinacea establishment capacity and competitiveness in upland habitats.