title: Ecophysiological variation of transpiration of pine forests: synthesis of new and published results.
abstract: Canopy transpiration (EC) is a large fraction of evapotranspiration, integrating physical and biological processes within the energy, water, and carbon cycles of forests. Quantifying ECis of both scientific and practical importance, providing information relevant to questions ranging from energy partitioning to ecosystem services, such as primary productivity and water yield. We estimated ECof four pine stands differing in age and growing on sandy soils. The stands consisted of two wide-ranging conifer species: Pinus taeda and Pinus sylvestris, in temperate and boreal zones, respectively. Combining results from these and published studies on all soil types, we derived an approach to estimate daily ECof pine forests, representing a wide range of conditions from 35° S to 64° N latitude. During the growing season and under moist soils, maximum daily EC(ECm) at day-length normalized vapor pressure deficit of 1 kPa (ECm-ref) increased by 0.55 ± 0.02 (mean ± SE) mm/d for each unit increase of leaf area index (L) up to L = ~5, showing no sign of saturation within this range of quickly rising mutual shading. The initial rise of ECmwith atmospheric demand was linearly related to ECm-ref. Both relations were unaffected by soil type. Consistent with theoretical prediction, daily ECwas sensitive to decreasing soil moisture at an earlier point of relative extractable water in loamy than sandy soils. Our finding facilitates the estimation of daily ECof wide-ranging pine forests using remotely sensed L and meteorological data. We advocate an assembly of worldwide sap flux database for further evaluation of this approach.
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, 27708, USA.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.|Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Pantana
authors.initials: P
authors.lastname: Tor-Ngern
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, 27708, USA.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.|Hydrospheric-Atmospheric Research Center, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan.
authors.forename: Ram
authors.initials: R
authors.lastname: Oren
authors.affiliation: USDA Forest Service Coweeta Hydrologic Laboratory, 3160 Coweeta Lab Road, Otto, North Carolina, 28763, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Oishi
authors.affiliation: School of Public Affairs, Arizona State University, Phoenix, Arizona, 85004, USA.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Uebelherr
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, 27708, USA.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.
authors.forename: Sari
authors.initials: S
authors.lastname: Palmroth
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.
authors.forename: Lasse
authors.initials: L
authors.lastname: Tarvainen
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.
authors.forename: Mikaell
authors.initials: M
authors.lastname: Ottosson-Löfvenius
authors.affiliation: Southern Swedish Forest Research Centre, SLU, P.O. Box 49, Alnarp, SE-230 53, Sweden.
authors.forename: Sune
authors.initials: S
authors.lastname: Linder
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, 27708, USA.|UMR 1391 ISPA INRA, Bordeaux Sciences AGRO, 1 Cours du général de Gaulle, Gradignan Cedex, 33175, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Domec
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, SE-901 83, Sweden.
authors.forename: Torgny
authors.initials: T
authors.lastname: Näsholm
mesh_terms: D000367:Age Factors; D065928:Forests; D009657:North Carolina; D041605:Pinus sylvestris / Q000502:physiology*; D041603:Pinus taeda / Q000502:physiology*; D018526:Plant Transpiration; D012987:Soil; D013548:Sweden
chemical_list: D012987:Soil
keywords: 
  Pinus sylvestris
  ; 
  Pinus taeda
  ; canopy transpiration; leaf area index; relative extractable water; soil texture; vapor pressure deficit