Wood Science and Technology

, Volume 53, Issue 2, pp 407–424 | Cite as

Water potential gradient between sapwood and heartwood as a driving force in water accumulation in wetwood in conifers

  • Ryogo NakadaEmail author
  • Naoki Okada
  • Takahisa Nakai
  • Katsushi Kuroda
  • Satoshi Nagai


Wetwood, water accumulation in the heartwood of tree trunks, is a defect of forest trees and needs to be improved for wood utilization. To understand the mechanism of wetwood formation, differences in water potential between sapwood and heartwood and their seasonal changes were investigated. The water potential of specimens sampled from tree trunks using an increment corer was measured by psychrometry at four-week intervals for 2 years in two coniferous species. A water potential gradient from sapwood to heartwood was identified that could provide a driving force of the radial water movement, and this gradient was found to fluctuate seasonally. The two species studied differed in seasonal change in water potential. The source of the water potential gradient is thought to be heartwood-accumulated potassium and water-soluble heartwood substance. The hypothesis is proposed that water movement from sapwood to heartwood during wetwood formation involves vaporous rather than liquid water and occurs over a limited season.



The authors acknowledge Drs. Ryo Funada, Youki Suzuki, Yuzo Sano, Takanori Imai and Satoshi Nakaba for assistance and discussion in this study, and Mr. Shinichi Sato for assistance in the field experiment.


This study was funded by Japan Society for the Promotion of Science, JSPS KAKENHI (JP23380105, JP26450241, 17K07882).

Compliance with ethical standard

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

226_2019_1081_MOESM1_ESM.xlsx (50 kb)
Supplementary material 1. Data in this study. Climatic data obtained from the Japan Meteorological Agency’s website and results from the measurement of water potential and DIFF (XLSX 50 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Hokkaido Regional Breeding Office, Forest Tree Breeding CenterForestry and Forest Products Research InstituteEbetsuJapan
  2. 2.Graduate School of Global Environmental StudiesKyoto UniversityKyotoJapan
  3. 3.Graduate School of BioresoursesMie UniversityTsuJapan
  4. 4.Forestry and Forest Products Research InstituteTsukubaJapan
  5. 5.Hyogo Prefectural Technology Center for Agriculture, Forestry and FisheriesShisoJapan

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