Abstract

Previous leaf-scale studies of carbon assimilation describe short-term resource-use efficiency (RUE) trade-offs where high use efficiency of one resource requires low RUE of another. However, varying resource availabilities may cause long-term RUE trade-offs to differ from the short-term patterns. This may have important implications for understanding canopy-scale resource use and allocation. We used continuous gas exchange measurements collected at five levels within a Norway spruce, Picea abies (L.) karst., canopy over 3 years to assess seasonal differences in the interactions between shoot-scale resource availability (light, water and nitrogen), net photosynthesis (A(n)) and the use efficiencies of light (LUE), water (WUE) and nitrogen (NUE) for carbon assimilation. The continuous data set was used to develop and evaluate multiple regression models for predicting monthly shoot-scale A(n). These models showed that shoot-scale A(n) was strongly dependent on light availability and was generally well described with simple one- or two-parameter models. WUE peaked in spring, NUE in summer and LUE in autumn. However, the relative importance of LUE for carbon assimilation increased with canopy depth at all times. Our results suggest that accounting for seasonal and within-canopy trade-offs may be important for RUE-based modelling of canopy carbon uptake.Resource use efficiency (RUE) is a key trait in determining the ability of plants to assimilate carbon. We demonstrate that the use efficiencies of light, water and nitrogen in determining the shoot-scale carbon uptake peak at different times of the year in a Norway spruce canopy, but also that the RUE interaction becomes increasingly dominated by light use efficiency with canopy depth at all times of the year. These temporal and spatial patterns in RUE interactions may have important implications for within-canopy resource allocation and for RUE-based modelling of canopy-scale carbon uptake. The study was based on continuous half-hourly gas exchange measurements conducted over a period of three years along a vertical canopy gradient in a mature Norway spruce stand.

Keywords

Picea abies; light-use efficiency; nitrogen-use efficiency; photosynthesis; stomatal conductance; transpiration; water-use efficiency

Published in

Plant, Cell and Environment
2015, Volume: 38, number: 11, pages: 2487-2496
Publisher: WILEY-BLACKWELL

SLU Authors

• Tarvainen, Lasse

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

Sustainable Development Goals

SDG15 Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1111/pce.12565

Permanent link to this page (URI)

https://res.slu.se/id/publ/68881