Abstract

Large‐scale peat extraction, in Finland and elsewhere, typically takes place on rather small extraction sites but has major impacts on surrounding aquatic and terrestrial ecosystems. The environmental conditions prior to drainage (baseline conditions) must be quantified in a statutory environmental impact assessment (EIA), but this is generally difficult due to lack of historical data. In this study, we developed and tested a method for EIA based on a reference area approach and remote sensing. The method calculates the normalized difference vegetation index in preextraction and postextraction periods using Landsat images of affected areas and reference surrounding areas. In a case study, we applied the method to assess changes after peat extraction at a site in northern Finland. The peat extraction area showed significant transformation from peatland vegetation to bare soil. Adjacent areas downstream and upstream were also affected by extraction. These results indicate that our method is a useful tool for EIA of peatland drainage.