Impact of climate warming on plant growth varied according to the season

Climate changes will promote the growth of invasive aquatic macrophytes. The aim of our study was to analyse the responses of three invasive plants (Elodea canadensis, Egeria densa and Lagarosiphon major) to a temperature increase of 3 °C in spring, summer and winter. At each season we measured four functional traits: the Relative Growth Rate ‘RGR’, Relative Leaf surface area Growth Rate, number of lateral branches and roots. E. canadensis showed the highest growth and vigour in spring and in summer. The Relative Growth Rate was enhanced by an elevation of temperature for E. canadensis and for E. densa. A 3 °C temperature increase stimulated root production for all species in summer, whereas the number of lateral branches was favoured in spring for E. canadensis. Climate warming had a greater impact on plant growth in spring than in summer and late winter. The response of species to climate warming was species-specific and so an increase in temperature should favour the spread of E. canadensis.