Effect on different climate on N2O metabolism in forest tree tisssues

This study explores how climate and tree species influence nitrous oxide (N2O) metabolism in forest trees across a transect from temperate to subarctic regions. Using incubation experiments on shoot material and internal gas measurements from stem wood, along with targeted metagenomics, we assessed N2O production, consumption, and microbial gene abundance in four tree species: Fagus sylvatica (European beech), Carpinus betulus (European hornbeam), Betula sp. (birch), and Picea abies (Norway spruce). Results showed spruce shoots in boreal regions showed high N2O production; beech shoots in temperate regions showed high consumption. Birch stems had the highest N2O concentration; spruce stems had the lowest. Metagenomic analysis revealed high relative abundance of the nitrous oxide reductase gene (nosZ) in spruce shoots and birch and beech wood cores, indicating active microbial N2O reduction. Additionally, shoots generally had higher nitrite content than wood cores, suggesting tissue-specific microbial activity. These findings highlight the complex interactions between climate, tree species, and microbial communities in regulating N2O dynamics, with implications for understanding forest contributions to greenhouse gas fluxes.