Climatic and Physiological Background of Ice Encasement Damage of Herbage Plants

Abstract

Plants encased for days or weeks in a compact ice sheet during winter are frequently killed, causing economic losses and problems in producing human food or animal feed. This occurs frequently in northern maritime areas with high winter precipitation and unstable winter temperatures. Ice is formed during short or long thaw periods in winter when snow melts and refreezes into a long-lasting ice cover. The longer the ice cover lasts the more severe the damage. The damage is most common on leveled fields as the meltwater runs off faster from sloping areas. Also the ice stays longer in depressions that have accumulated water. The first sign of cell damage is detected on the membranes. Plants encased in ice turn to anaerobic respiration and produce metabolites which become toxic to the plant itself. In addition, reactive oxygen species (ROS) may harm the cells when plants return to air in spring. In recent decades the frequency of ice encasement damage has decreased in Iceland. This has been a result of climate change, which is expected to increase the winter temperature substantially in the near future. Ice encasement damage will then disappear from the agricultural areas in the lowland, but might instead appear in highland or areas further north. This might become a threat for alpine vegetation which has not been naturally selected through the ages for this kind of stress.