Grant: Collaborative Research and Development Grants

Elevated levels of heavy metals close to mines, smelters and refineries, such as found around Sudbury, Ontario, reduce the growth of plants and can even be lethal for them. The resulting soil exposure leads to erosion and emissions of metal-containing dust in the surroundings. Phytoremediation, i.e., planting vegetation on the affected area is a cost-effective means to mitigate the environmental effects of metal-contaminated sites, but the used plants have to be able to tolerate heavy metals, and frequently also drought, as metal-contaminated sites tend to have poor soils. Effects of low levels of metals on plants under field conditions are not well known, but it has been shown that physiological changes occur, possibly interfering with the plant's ability to tolerate other stresses such as drought. In the current project the effect of low levels of heavy metals on plants' ability to cope with drought will be investigated, using plants with contrasting metal tolerances. Metals are known to influence physiological and morphological traits associated with water uptake and water regulation, but experiments directly testing the interactions of these two stresses are rare. In this project the effects of mixtures of heavy metals as found in Sudbury area soils on water uptake and regulation in white birch and red maple under different watering regimes will be tested. As water use of plants is an important factor affecting soil moisture, the feedback of metal effects on soil water will be investigated at ecosystem level. The investigation will be conducted using trees, as they are important for sustainable long-term restoration of ecosystem functions, for stabilizing the soil and for reducing wind speeds and dust development. The study will deliver information about the interactions between phenotypic and genetic responses to heavy metal stress, and drought, and information to what extent observed problems of deciduous trees in restored areas are related to metal-drought interaction. The results will help long-term planning of mitigating environmental effects of mining industry and possibly help finding tolerant genotypes useful for restoration activities.