Reindeer and the carbon cycle in Finland’s north
Not all climate heroes wear capes. Some sport antlers. A recent study published in Science of the Total Environment shows that reindeer grazing in Finland’s northern forests may help stabilise the carbon stored in soil and understory vegetation. By grazing through snow-covered undergrowth, these arctic herbivores influence how much carbon is released or retained during the growing season.
Northern forests store a significant portion of the world’s terrestrial carbon. While trees are the most visible carbon sinks, soil, lichens, mosses, and other low-growing plants also play a crucial role. In this context, researchers from the University of Oulu sought to understand how reindeer activity interacts with winter snow cover to shape the carbon balance in these fragile ecosystems.
The study setup: long-term experiments in two Finnish sites
Between 2019 and 2023, scientists carried out experiments in areas where reindeer graze and in sites where grazing has been excluded for decades: 25 years at Oulanka in eastern Finland and 55 years at Kevo in the far north. In both locations, researchers manipulated snow depth to create patches of deeper and shallower snow. They then monitored carbon release during the subsequent summer to see how grazing and snow interact to influence the carbon cycle.
What the results suggest about grazing and carbon stability
The findings reveal a striking contrast between ungrazed and grazed areas. In the 55-year ungrazed zone, shallow snow led to higher carbon release from both the understory and soil, while deeper snow reduced emissions. Conversely, in areas where grazing continued— including the 25-year Oulanka site—carbon release remained more stable regardless of snow depth changes. This buffering effect suggests that ongoing reindeer activity can dampen the carbon responses to winter climate variability.
Lead author Noora Kantola notes that this pattern may indicate northern coniferous forests could exhibit a degree of resilience to short-term winter climate fluctuations, thanks to the presence of reindeer and their grazing behavior. In other words, the herbivores’ foraging and trampling help maintain a steadier carbon balance than might be expected in a changing climate.
Why the understory matters
The study points to the understory as a key player in the carbon story. In long-ungrazed areas, lichen and other low-lying vegetation recover over time, altering how warmth and moisture move between air and soil. Changes in these microclimates can influence soil temperature and moisture, which in turn affect soil decomposers and the rate at which carbon is released back into the atmosphere. Kantola explains that in Kevo— where lichen cover has substantially recovered—these shifted conditions may interact with snow depth to shape carbon dynamics in the soil.
Implications for forest health and climate policy
While this research does not imply that reindeer grazing is a panacea for climate change, it underscores a nuanced role for wildlife in carbon cycling. Active grazing and trampling in northern forests appear to contribute to a more stable carbon store over the studied timescales. This highlights the interconnectedness of wildlife management, forest health, and climate outcomes, suggesting that policies supporting balanced grazing regimes could have climate benefits alongside ecological ones.
Conclusion: a reminder that some climate solutions are found in the wild
The take-home message is clear: when reindeer graze as they have for generations, they do more than support their populations and the forests they inhabit. They may also contribute to the stability of the planet’s carbon reservoir by moderating how much carbon is released during variable winter conditions. As Northern forests continue to be a pivotal part of the global carbon puzzle, the humble reindeer stands as a reminder that natural processes often work in concert with climate science to shape a more resilient future.
