Temperature and water potential co-limit stem cambial activity along a steep elevational gradient.

Area of Science:

• Forest ecology
• Plant physiology
• Dendrochronology

Background:

• Tree growth models struggle to differentiate between carbon assimilation and biophysical limitations.
• Understanding the drivers of wood formation is crucial for predicting tree responses to environmental change.

Purpose of the Study:

• To assess the biophysical effects of temperature and water potential on conifer wood formation.
• To develop a model simulating these effects on cambial activity and tracheid production.

Main Methods:

• Multiannual, weekly wood formation monitoring of Larix decidua and Picea abies in the Swiss Alps.
• Development of a model linking water potential (turgor) and temperature (enzymatic activity) to cambial division.
• Validation of the model against observed tracheid production data.

Main Results:

• The model accurately reproduced observed tracheid production phenology and dynamics within years.
• Temperature primarily determined the onset of tracheid production.
• Water potential was essential for predicting the cessation of production and annual tracheid yield.

Conclusions:

• Intra-annual tree cambial activity is significantly constrained by temperature and water potential, irrespective of carbon assimilation.
• These biophysical factors are key drivers of wood formation at various elevations.
• Interannual variations in tree growth may involve interactions between biophysical constraints and other environmental factors.