Abstract
The nitrous oxide (N(2)O) dynamics in boreal forests are better known at the ecosystem scale, with greater uncertainty associated with specific ecosystem compartments. We investigated the N(2)O dynamics of the lichen Platismatia glauca in boreal forests near Kuopio, North Savo, Finland. At the study sites, P. glauca is the most abundant lichen colonising Norway spruce (Picea abies). Despite their abundance, the contribution of epiphytic lichens like P. glauca to N(2)O dynamics in boreal forests has received little attention. By incubating P. glauca, we assessed the effects of moisture, temperature, and oxygen availability on its N(2)O dynamics. We observed net N(2)O consumption potential, particularly at +5°C at aerobic condition. Quantitative real-time PCR analysis targeting the N(2)O reductase gene fragment (nosZ) revealed that it was present and active in both in situ and incubated lichens. nosZ transcription was higher at +5°C. Clade I nosZ was dominant, with most sequences affiliated with the order Rhizobiales. We confirmed the presence of nosZ gene with targeted metagenomics sequencing. Our results demonstrate that P. glauca acts as a net consumer of N(2)O, with potential ranging between 0.1 and 0.4 ng N(2)O-N g DW(-1) h(-1) under aerobic conditions.