Changes in biomass allocation buffer low CO₂ effects on tree growth during the last glaciation

Guangqi Li*, Laci M. Gerhart, Sandy P. Harrison, Joy K. Ward, John M. Harris, I. Colin Prentice

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)
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    Isotopic measurements on junipers growing in southern California during the last glacial, when the ambient atmospheric [CO₂] (cₐ) was ~180 ppm, show the leaf-internal [CO₂] (cᵢ) was approaching the modern CO₂ compensation point for C₃ plants. Despite this, stem growth rates were similar to today. Using a coupled light-use efficiency and tree growth model, we show that it is possible to maintain a stable cᵢ/cₐ ratio because both vapour pressure deficit and temperature were decreased under glacial conditions at La Brea, and these have compensating effects on the cᵢ/cₐ ratio. Reduced photorespiration at lower temperatures would partly mitigate the effect of low cᵢ on gross primary production, but maintenance of present-day radial growth also requires a ~27% reduction in the ratio of fine root mass to leaf area. Such a shift was possible due to reduced drought stress under glacial conditions at La Brea. The necessity for changes in allocation in response to changes in [CO₂] is consistent with increased below-ground allocation, and the apparent homoeostasis of radial growth, as cₐ increases today.
    Original languageEnglish
    Article number43087
    Pages (from-to)1-9
    Number of pages9
    JournalScientific Reports
    Publication statusPublished - 24 Feb 2017

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    Copyright the Author(s) 2017. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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