Unearthing the Role of Root Carbon in Liberating Nitrogen in Boreal Forest

To combat climate change, we must achieve net zero.

Boreal forests store 90×1012 kg carbon (C) in vegetation and 470×1012 kg C in soil, responsible for 20-30% of terrestrial C storage.

They can decelerate climate change if elevated CO2 enhances their productivity but only provided that sufficient soil nitrogen (N) becomes available to support their growth and soil C is not undermined.

Pressingly, stakeholders and the public have been insufficiently informed of this significant role of boreal soil.The key mechanism for linking forest productivity and soil C/N cycling is that fresh root C exudates enhance microbial decomposition of soil organic matter (SOM), increasing N availability at the expense of soil C—so-called “Priming”.

However, we do not know how priming regulates decomposition.I will perform a large-scale tree C-transport manipulation experiment in a boreal forest using the stem compression technique (which reduces root C supply) to test root C effects on soil C/N economy and communicate findings with governmental agencies, stakeholders and the public.

I will test the novel hypothesis that root C supply enhances SOM decomposition by oxidative enzymes and liberates N from C-rich, nonhydrolysable compounds.We do NOT know C cost of N mobilisation by priming, but we WILL after this project by establishing a novel theoretical framework of SOM decomposition.

This will deliver insights into targeted forest management to strategically achieve net zero.