Abstract

Canopy transpiration (E-C) is a large fraction of evapotranspiration, integrating physical and biological processes within the energy, water, and carbon cycles of forests. Quantifying E-C is 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 E-C of 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 E-C of pine forests, representing a wide range of conditions from 35 degrees S to 64 degrees N latitude. During the growing season and under moist soils, maximum daily E-C (E-Cm) 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 = similar to 5, showing no sign of saturation within this range of quickly rising mutual shading. The initial rise of E-Cm with atmospheric demand was linearly related to ECm-ref. Both relations were unaffected by soil type. Consistent with theoretical prediction, daily E-C was 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 E-C of 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.

Keywords

canopy transpiration; leaf area index; Pinus sylvestris; Pinus taeda; relative extractable water; soil texture; vapor pressure deficit

Published in

Ecological Applications
2017, Volume: 27, number: 1, pages: 118-133
Publisher: WILEY-BLACKWELL

SLU Authors

• Pantana, Tor-Ngern

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Chulalongkorn University
  • Duke University

• Oren, Ram

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Duke University
  • Nagoya University

• Palmroth, Sari

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Duke University

• Tarvainen, Lasse

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Ottosson Löfvenius, Mikaell

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Linder, Sune

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

• Näsholm, Torgny

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1002/eap.1423

Permanent link to this page (URI)

https://res.slu.se/id/publ/79777