Arbuscular mycorrhizal trees expanded their dominance across the Japanese archipelago over a 15-year period, driven by climate warming and the spread of tree diseases, according to research published in Nature Communications. The broad-scale transition alters nutrient dynamics in temperate forest ecosystems faster than earlier ecological models anticipated.
Researchers evaluated tree species and genera across more than 13,000 forest plots throughout temperate East Asia. By measuring basal area proportions, the team tracked how tree symbioses changed across the archipelago. The findings show that arbuscular mycorrhizal trees gained ground significantly over the 15-year monitoring window, diminishing the relative presence of other fungal symbioses in those forest stands.
The shift directly alters forest soil chemistry. Field data showed that arbuscular mycorrhizal tree dominance holds a negative relationship with the ratio of soil carbon to nitrogen stocks. This dynamic suggests that changes in tree symbiosis will alter how temperate forest soils retain and release nitrogen.
Biotic disturbances played a central role in driving the recorded change. Rising temperatures combined with pest and disease pressures accelerated the replacement of existing trees, prompting the authors to stress forest pest and disease control as a mechanism to slow symbiosis shifts and protect ecosystem functions.
The study was conducted by researchers from Japan's Forestry and Forest Products Research Institute, the University of Tokyo, the National Institute for Environmental Studies, and Osaka University. The Japan Society for the Promotion of Science supported the research under KAKENHI grant numbers JP25K18272 and JP24K01817.
