Genetic variation in leaf traits and gas exchange responses to vapor pressure deficit in contrasting conifer species

Mechanistically predicting the evolutionary response of tree species to climate change requires an understanding genetic variation in relevant traits. Here we compared phenotypic and Leaf Economics Spectrum (LES) traits gas exchange vapour pressure deficit (VPD) lodgepole pine (Pico) white spruce (Pigl), early a late successional dominating boreal forests western Canada. We measured exchange, foliar nitrogen lamina mass area ratio 697 c. 30-year-old trees two field progeny trials. analysed rates VPD using novel quantitative model, function-valued trait approach. Pico showed greater LES photosynthetic rate than Pigl, but no significant difference their correlations between less sensitive stomatal Pigl sensitivity. In contrast, positive correlation values sensitivity conductance under low VPD. Our study region is projected see increase with change; genetically diverse could make this more vulnerable climate-change-induced droughts. A free Plain Language Summary can be found within Supporting Information article.