Increased Cold Damage to Plants With Warmer Springs?


Plant ecologists have long been concerned that global warming (caused in large part by energy production from fossil fuels) may actually increase the risk of plant frost damage. The underlying hypothesis is that mild winters and warm, early springs, which are expected to occur as warming continues, may induce “premature” leaf growth in many ecosystems, resulting in exposure of young leaves to subsequent late-spring frosts. The 2007 spring freeze in the eastern United States provided an excellent opportunity to evaluate this hypothesis and assess its potential consequences. A group of BER-sponsored researchers at Oak Ridge National Laboratory (collaborating with NASA, NOAA, and university scientists) analyzed the course of events over a period of early spring leaf growth, caused by unusually warm conditions, followed by a dramatic (and unusual) regional-scale late-spring freeze. The freeze resulted in regional-scale leaf damage and death, with extensive defoliation at many locations, which was observed from the ground and in satellite data. The researchers concluded that the possibility of future increased fluctuations in spring temperatures pose a real threat to some plants in temperate climates. The results were published in the March issue of BioScience.