Hagner, M, Manninen, O, Peltola, R, Ranta, K, Hietanen, J & Uusitalo, M 2026, 'Circular economy side streams accelerate ecosystem recovery on mine tailings in northern conditions', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-11, https://doi.org/10.36487/ACG_repo/2615_65
(https://papers.acg.uwa.edu.au/p/2615_65_Hagner/)
Abstract: Ecosystem restoration on mine tailings in northern conditions is constrained by limited availability of suitable cover materials, short growing seasons, cold winters and nutrient-poor substrates. Estimates indicate that natural till resources are insufficient to meet the cover structure needs of existing and closed mines, highlighting the need for alternative materials.
In summer 2024, a 1,200 m² restoration experiment was established on the Pahtavaara mine tailings area in Sodankylä, northern Finland. The study investigates whether circular economy side streams can replace part of the mineral cover material while accelerating vegetation establishment, improving water management, and supporting long-term ecosystem recovery in mine tailings.
Twelve 25 × 5 m strips were established in a randomised design. Growth media treatments included composted sewage sludge (CSS), CSS mixed with biochar, CSS mixed with sewage sludge ash (3 replicates each), and untreated control strips. Vegetation representing dry meadow, fresh meadow, flood meadow and willow shrub zones was introduced using container-grown seedlings and seed mixtures of local Nordic species. Additional strips with identical growth media were covered with locally sourced meadow cuttings. Stones and deadwood were added to create microtopography and microhabitats.
The first vegetation survey conducted in summer 2025 recorded plant survival, growth and flowering of planted individuals, as well as seedling emergence in permanent plots. Results showed unexpectedly high seedling survival, vigorous growth and successful germination across organic growth media treatments. After only one growing season, the site had developed into a local biodiversity hotspot, attracting a diverse range of pollinators and amphibians. Notably, larvae of the rare Lapland species Saturnia pavonia were observed.
The results demonstrate that circular bioeconomy side streams can significantly accelerate ecosystem recovery on mine tailings in northern environments while reducing reliance on natural till.