title: The energetic and carbon economic origins of leaf thermoregulation.
abstract: Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories. Our results reveal that variation in leaf temperatures and physiological performance are tightly linked to leaf traits and carbon economics. The theory, parameterized with global averaged leaf traits and microclimate, predicts a moderate level of leaf thermoregulation across a broad air temperature gradient. These predictions are supported by independent data for diverse taxa spanning a global air temperature range of ∼60 °C. Moreover, our theory predicts that net carbon assimilation can be maximized by means of a trade-off between leaf thermal stability and photosynthetic stability. This prediction is supported by globally distributed data for leaf thermal and photosynthetic traits. Our results demonstrate that the temperatures of plant tissues, and not just air, are vital to developing more accurate Earth system models.
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, MS J495, Los Alamos, New Mexico 87545, USA.|Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Sean T
authors.identifier: 0000-0003-2158-6525
authors.initials: ST
authors.lastname: Michaletz
authors.affiliation: Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, Oklahoma 73069, USA.
authors.forename: Michael D
authors.identifier: 0000-0001-9080-0834
authors.initials: MD
authors.lastname: Weiser
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Nate G
authors.initials: NG
authors.lastname: McDowell
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, USA.|State Key Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.|Earth Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94270, USA.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, Oklahoma 73069, USA.|Smithsonian Tropical Research Institute, Balboa, Republic of Panama.
authors.forename: Michael
authors.initials: M
authors.lastname: Kaspari
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Brent R
authors.initials: BR
authors.lastname: Helliker
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.|The Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, New Mexico 87501, USA.|The iPlant Collaborative, Thomas W. Keating Bioresearch Building, 1657 East Helen Street, Tucson, Arizona 85721, USA.|Aspen Center for Environmental Studies, 100 Puppy Smith Street, Aspen, Colorado 81611, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Enquist
mesh_terms: D001833:Body Temperature Regulation; D002244:Carbon / Q000378:metabolism*; D004734:Energy Metabolism; D008954:Models, Biological; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology*; D018521:Plant Physiological Phenomena; D013696:Temperature
chemical_list: D002244:Carbon