Reindeer grazing as a quiet climate stabilizer
In the vast, snow-blanketed forests of Finland’s north, a surprising ally in the fight against climate change wears antlers. A four-year research project published in Science of the Total Environment reveals that reindeer grazing helps stabilize the carbon stored in the understory and soil of northern coniferous forests. While trees are rightly celebrated as carbon sinks, this study highlights that the low-growing vegetation and soil—eaten and trampled on by reindeer—play an essential, often overlooked role in maintaining the carbon balance.
The question researchers chased
The University of Oulu team set out to understand how reindeer grazing and winter snow cover interact to shape the carbon cycle in boreal Finland. They designed experiments from 2019 to 2023 in two contrasting landscapes: a long-standing ungrazed zone at Kevo in the far north and an area at Oulanka in eastern Finland where grazing has persisted for decades. In both sites, scientists manipulated snow depth to create patches of deeper and shallower snow, then measured how much carbon escaped from the understory and soil during the following summer. The goal was to see whether reindeer presence damps or amplifies climate-driven changes in carbon release.
What the sites revealed
The study found a striking difference between areas where reindeer continue to graze and those where grazing has been halted for decades. In the Kevo region, which had not seen grazing for 55 years, shallower snow amplified carbon release from the understory and soil, while deeper snow tended to curb it. By contrast, the Oulanka site, with ongoing grazing (and the 25-year ungrazed area nearby), showed a remarkable stability in carbon release regardless of snow depth. In other words, ongoing grazing appears to buffer the ecosystem against short-term winter climate fluctuations.
Why this buffering matters
The northern coniferous forests store roughly a third of the world’s terrestrial carbon. While trees capture carbon through growth, soil organic matter and the understory’s small plants also act as crucial reservoirs. The reindeer’s grazing and trampling modify the understory structure and microclimate, influencing how warmth and moisture move between air and soil. This creates conditions that can limit carbon loss during winter and spring transitions, effectively stabilizing the carbon cycle in the face of variable winter conditions.
Interpreting the ecological mechanism
Lead author Noora Kantola explains that the “buffering effect” of grazing may stem from how reindeer keep the understory in a state that moderates soil temperature and moisture. In Kevo’s decades-long ungrazed area, lichen and other low-lying vegetation have recovered differently, potentially altering heat exchange and water movement. When snow depth and understory structure interact, they influence soil decomposers—microbes and fungi that drive carbon release. With grazing, this interplay appears to dampen abrupt shifts in carbon flux, contributing to a steadier carbon budget across winter-to-summer transitions.
What this means for climate resilience
The researchers emphasize a broader implication: reindeer, by grazing and trampling vegetation, contribute to ecosystem resilience in northern forests. While the animals may seem distant from global climate policy, their impact on carbon stabilization suggests that wildlife management and habitat continuity are relevant to planetary health. It’s a reminder that climate solutions are intricate, involving living systems across scales—from microbe to mammal to forest.
Looking ahead
The study adds a crucial piece to the puzzle of how boreal ecosystems respond to changing winter conditions. It also invites further inquiry into how changes in snow patterns, reindeer populations, and understory recovery interact over longer timescales. If reindeer grazing continues to prove a stabilizing force, land-use strategies in northern regions could increasingly consider wildlife dynamics as part of carbon management and climate adaptation efforts.
Bottom line: when reindeer graze the northern forests, they’re not just sustaining a cultural landscape; they may also support the health of the planet by helping keep carbon locked away where it matters most.
