Responses of sapwood ray parenchyma and non-structural carbohydrates of Pinus sylvestris to drought and long-term irrigation

Georg von Arx, Alberto Arzac, Patrick Fonti, David Frank, Roman Zweifel, Andreas Rigling, Lucia Galiano, Arthur Gessler, José Miguel Olano

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Non-structural carbohydrates (NSC) play a crucial role in tree resistance and resilience to drought. Stem sapwood parenchyma is among the largest storage tissue for NSC in mature trees. However, there is a limited mechanistic understanding of how NSC reserves, stem parenchyma abundance and growth rates are interrelated, and how they respond to changing water availability. We quantified NSC, ray parenchyma abundance and ring width along four successive 5-year radial sapwood segments of the stem of 40 mature Pinus sylvestris trees from a 10-year irrigation experiment conducted at a xeric site in Switzerland. Percentage of ray volume (PERPAR) varied from 3·75 to 8·94% among trees, but showed low intra-individual variability. PERPAR responded positively to irrigation with a lag of several years, but was unrelated to %NSC. %NSC was lower in wider rings. However, wider rings still contained a larger NSC pool that was positively related to next year's ring growth. Our results suggest that stem ray parenchyma does not limit NSC storage capacity, but responds to long-term environmental drivers with years of delay. The observed carbon allocation patterns indicate a prioritization of storage over growth independent of growth conditions, likely as a mechanism to ensure long-term survival. Furthermore, NSC pool size proved to be a determinant for the inter-annual autocorrelation in tree-ring growth. Our study highlights the importance of long-term multi-parameter studies to better understand tree responses to environmental variability at different time-scales. A lay summary is available for this article.

Original languageEnglish (US)
Pages (from-to)1371-1382
Number of pages12
JournalFunctional Ecology
Issue number7
StatePublished - Jul 2017
Externally publishedYes


  • carbon allocation
  • drought stress
  • growth vs. storage
  • ring-width autocorrelation
  • structure–function relationships
  • tree-ring anatomy
  • xylem anatomy
  • xylem rays

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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