Sourcing the water that makes up tree biomass

Area of Science:

• Plant Physiology
• Isotope Hydrology
• Forest Ecology

Background:

• Traditionally, tree water uptake was attributed solely to root absorption from soil and subsurface sources.
• Stable isotope analysis of water has been crucial in tracing water sources for tree biomass.
• Recent evidence suggests non-root water uptake pathways are increasingly significant.

Discussion:

• This commentary reviews the evidence for direct water uptake by tree leaves and stems.
• It highlights the potential for foliar water uptake to be a dominant source for biomass synthesis.
• The role of stable isotopes in differentiating water sources is discussed.

Key Insights:

• Foliar water uptake, direct absorption by leaves and stems, can be a primary water source for tree biomass.
• This challenges the long-held view of exclusive root water uptake.
• A new experimental method by Kagawa provides strong evidence for foliar water uptake's significance.

Outlook:

• Further research is needed to quantify the contribution of foliar water uptake across different species and environments.
• Understanding these water pathways is critical for accurate tree water-use modeling.
• This discovery has implications for forest management and climate change adaptation strategies.