Climate warming suits water hyacinth

Posted on December 16, 2014

Water hyacinth (Eichhornia crassipes) is one of the most invasive and damaging aquatic plants. It’s a species of the tropics and subtropics, with a range that seems to be limited by low winter temperatures. Scientists in Hubei, southeast China, set up greenhouse experiments to examine the effects of temperature on the survival and growth of water hyacinth. To assess the likely impacts of climate warming, greenhouse temperatures (4.8 – 8.2 oC) were high relative to current winter mean temperatures in Hubei (3-7 oC). The experiments, with floating and bottom-rooted forms of water hyacinth, ran for three months. Plant survival was significantly affected by both temperature and the size of the stem: all floating plants with large stems survived, but in those with small stems, survival increased with temperature. Because the stem base is where carbohydrates are stored as energy reserves in autumn, a larger stem improves the chance of overwintering survival. In the case of the rooted plants, which were kept in moist sediment without surface water, survival was much higher when the stem base was buried in the sediment and insulated from the cooler air. As with survival, plant growth increased with temperature and with the size of the stem base. As temperature increased, relatively more biomass was allocated to shoots and less to stems. Therefore it seems that rising winter temperatures will probably have a strong positive effect on the survival and growth of water hyacinth, its ability to shade out competing aquatic plants, and its capacity to expand its geographical distribution.

Reference: You, W., Yu, D. Xie, D. & Yu, L. 2013. Overwintering survival and regrowth of the invasive plant Eichhornia crassipes are enhanced by experimental warming in winter. Aquatic Biology 19, 45–53.