title: Responses of tree species to heat waves and extreme heat events.
abstract: The number and intensity of heat waves has increased, and this trend is likely to continue throughout the 21st century. Often, heat waves are accompanied by drought conditions. It is projected that the global land area experiencing heat waves will double by 2020, and quadruple by 2040. Extreme heat events can impact a wide variety of tree functions. At the leaf level, photosynthesis is reduced, photooxidative stress increases, leaves abscise and the growth rate of remaining leaves decreases. In some species, stomatal conductance increases at high temperatures, which may be a mechanism for leaf cooling. At the whole plant level, heat stress can decrease growth and shift biomass allocation. When drought stress accompanies heat waves, the negative effects of heat stress are exacerbated and can lead to tree mortality. However, some species exhibit remarkable tolerance to thermal stress. Responses include changes that minimize stress on photosynthesis and reductions in dark respiration. Although there have been few studies to date, there is evidence of within-species genetic variation in thermal tolerance, which could be important to exploit in production forestry systems. Understanding the mechanisms of differing tree responses to extreme temperature events may be critically important for understanding how tree species will be affected by climate change.
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA.
authors: Robert
authors: R
authors: Teskey
authors: Institute for Genomic Biology, University of Illinois, Urbana, IL, 61801, USA.
authors: Timothy
authors: T
authors: Wertin
authors: Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, B-9000, Belgium.
authors: Ingvar
authors: I
authors: Bauweraerts
authors: Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, B-9000, Belgium.
authors: Maarten
authors: M
authors: Ameye
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA.
authors: Mary Anne
authors: MA
authors: McGuire
authors: Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, B-9000, Belgium.
authors: Kathy
authors: K
authors: Steppe
mesh_terms: D018533:Biomass; D055864:Droughts; D005818:Genetic Engineering; D006358:Hot Temperature; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D013312:Stress, Physiological; D014197:Trees / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
keywords: drought; genotype; growth; heat stress; photosynthesis; respiration; stomatal conductance