Welcome to this brief reading pack of research summaries on how forest management affects soil carbon. The following concise summaries cover recent Finnish studies on nitrogen fertilization, thinning, clear‑cutting and their differing impacts on mineral soils and drained peatlands. Please note: the full original articles are available in Finnish only. These studies are part of EU-funded HoliSoils project, coordinated by Raisa Mäkipää, who is also a research professor of UNITE.
Nitrogen fertilization increases carbon storage in pine forests
A study in Finnish Scots pine forests found that nitrogen fertilization increases carbon storage in forest soils. Over several years, fertilized plots showed higher soil carbon sequestration compared with unfertilized controls, even though tree growth initially accelerated and needle litter quality changed. The results suggest that adding nitrogen can enhance long-term soil carbon accumulation in these forest ecosystems, with implications for forest management and climate mitigation strategies.
Full article: https://www.luke.fi/fi/uutiset/typpilannoitus-lisaa-hiilen-varastoitumista-maaperaan-mantymetsissa
Thinning reduced the forest’s carbon sink – on mineral soil, the effect was temporary, while in drained peatland forests, emissions continued for longer
Thinning reduced the forest carbon sink on mineral soils, but the effect was temporary. In drained peatland forests, emissions continued for longer, and thinning can prolong the recovery time for carbon stocks there. The study highlights that soil type and site conditions strongly influence how forest management affects carbon sinks.
Clear-cutting weakens forest soil carbon stocks for decades
Clear-cutting reduces soil carbon stocks for decades. After clear-cutting, soil carbon losses occur due to increased decomposition and reduced litter input; recovery is slow and can take many decades depending on site conditions. The study warns that frequent or extensive clear-cutting can significantly weaken forests’ long-term carbon storage, so management practices and landscape-level planning should account for these long-lasting soil carbon impacts.
Full article: https://www.luke.fi/fi/uutiset/avohakkuut-heikentavat-metsan-maaperan-hiilivarastoja-vuosikymmeniksi
Repeated nitrogen fertilization on nutrient-poor mineral soils could be a concrete means of promoting emission targets
Repeated nitrogen fertilization on nutrient-poor mineral soils could be a practical way to advance emission reduction targets. The study found that regular N additions increased soil carbon storage and altered forest growth and litter dynamics, suggesting targeted fertilization on low-productivity sites can enhance carbon sequestration. The authors note site-specific responses and recommend weighing benefits against potential ecological risks and management goals.