Tree‐ring isotope analysis of Norway spruce suffering from long‐term infection by the pathogenic white‐rot fungus Heterobasidion parviporum

Summary We report for the first time a tree-ring isotopic analysis on host trees infected with Heterobasidion parviporum. By measuring carbon and oxygen stable isotope ratios in tree rings over ca. 150 years of forest growth, we obtained evidence that stomatal conductance increases in Picea abies affected by H. parviporum. We put forward this approach as a novel way of providing an insight into plant–pathogen relationships during tree life.