Soil carbon in the boreal region under climate and land use change

Carbon cycling in boreal regions is controlled naturally by fire disturbance, climate, hydrology, snowmelt, soil heterogeneity, acidity, low nitrogen and phosphorus availability, mycorrhizal distribution, plant cover, and cryoturbation/permafrost at the northern edge. It is primarily altered by human management via and following land clearance. Each factor interacts with others in complex ways, creating a system characterized by high carbon storage and shaped by natural and anthropogenic disturbance. This paper examines boreal research to answer the question: ‘what are the primary factors controlling boreal carbon cycling?’ Though climate change threatens boreal systems, they may yet be resilient given many natural feedback loops that resist massive carbon loss. Perhaps the greatest danger is land conversion, which causes permanent losses and drastic alteration of certain carbon pools. Accordingly, it might be argued that it would be overall better to implement policies that keep these lands as forests, including managed forests, rather than convert to agriculture. Conversely, farming of marginal boreal soils might be managed to enhance carbon storage while satisfying local food security needs. However, the impact of agriculture on soil carbon storage is yet to be effectively quantified and initial results offer inconsistent assessments, reflected in the as‐yet natural sciences data‐scarce policy development. Research targeting long‐term carbon cycling, land conversion practices, agroforestry, and communication between boreal scientists and other groups (climate scientists, policymakers, public, and farmers) must be addressed through creation of long‐term experiments.