Effect of rhizome exposure to contrasting abiotic conditions on the performance of the invasive macrophyte Hedychium coronarium J. Koenig (Zingiberaceae)

Abstract

Although invasive species are often better competitors than native species, broad environmental tolerance may also drive invasion success. Tolerance to abiotic heterogeneity in riparian ecosystems tends to favour the establishment of alien clonal species, as well as their dispersion by vegetative fragments. Hedychium coronarium J. Koenig is a rhizomatous emergent macrophyte native to Asia and has invaded Neotropical riparian ecosystems. We assessed the effect of H. coronarium rhizome exposure to distinct abiotic conditions on ramet growth. We exposed rhizomes to different desiccation periods (1–90 days), temperatures (15, 25 and 35 °C), and light regimes (0, 12, 16 h) and then assessed the effect of each of these variables on subsequent clonal growth (aboveground biomass production per plant and per ramet, and number and height of ramets) under ambient conditions. While no rhizome survived desiccation periods longer than 30 days, ramet growth among surviving rhizomes was not affected by the period of desiccation. Biomass production per rhizome, ramet biomass, and ramet height were significantly lower at 35 °C than at 25 °C. Constant darkness increased rhizome survival, but decreased ramet growth. Although rhizome exposure to extremes of each abiotic variable may hinder the invasion success of H. coronarium, the subsequent aboveground biomass production of surviving rhizomes did not decrease strongly in response to any treatment. This resilience may contribute to successful establishment of H. coronarium after dispersal through rhizome fragments and to varying abiotic conditions.