The project investigates the effect of nitrogen addition on the decomposition of lignin, a major component of plant material that is highly resistant to degradation. By adding nitrogen to the soil, we aim to understand its impact on microbial activity, enzyme production, and overall decomposition rates.

Using Populus tremula (Aspen wood) clones with varying lignin content as model substrates, we conducted a 56-week incubation experiment under controlled laboratory conditions. We monitored CO2 production and employed advanced techniques like 2D HSQC NMR to analyze changes in lignin composition. Additionally, we assessed microbial community structure through sequencing of 16S rRNA and ITS markers, and measured oxidative enzyme activity.

We hypothesise that nitrogen addition will suppress overall decomposition and reduce lignin degradation. We expect that high-lignin substrates will degrade slower compared to low-lignin substrates under nitrogen treatment. The study aims to elucidate the intricate interactions between nitrogen availability, microbial community dynamics, and lignin degradation processes in boreal forest soils, providing insights into the broader implications for carbon storage and climate change.