Reindeer grazing in northern pine forests does more than change what grows above ground. A study from Finland found that grazed forests had nearly 30% less shallow-root biomass than areas fenced off from reindeer for 50 to 100 years. The biggest losses were in the top 5 cm of soil, and roots in grazed areas were shorter, thicker, and less branched. That root shift matters for carbon because roots are a main pathway for carbon entering boreal forest soils. Researchers estimate roots account for 50-70% of the carbon that reaches the soil in northern coniferous forests. Thinner lichen cover from grazing also exposed soil to colder winter temperatures, down to -10 C compared with -5 C in ungrazed areas, which may explain part of the root damage. The study was led by Umeå University with the University of Oulu and published in Oikos. It adds evidence that land management choices, including grazing pressure, can affect below-ground carbon storage in boreal ecosystems.
