Uncertainty in paired-catchment studies – does nitrogen export increase after forest drainage?

Ari Laurén, Harri Koivusalo, Sakari Sarkkola, Erkki Ahti, Sirkka Tattari, Tuija Mattsson, Samuli Joensuu and Leena Finér

After Wise Use – The Future of Peatlands, Proceedings of the 13th International Peat Congress: Peatland Forestry

ditching, nitrogen, paired-catchment, water-protection

Lauren et al. 2008: Uncertainty in paired-catchment studies


Paired-catchment studies are used to quantify the effect of land management on nutrient export to water bodies. In these studies, a treatment effect is represented as a difference between the observed and estimated ‘natural state’ exports. The ‘natural state’ export is calculated using a regression model between the nutrient exports from control and from treatment catchments for the pre-treatment dataset. The uncertainty in the pre-treatment regression is usually ignored. We examined how this uncertainty was reflected in the treatment effects of forest drainage on nitrogen export in two paired catchments in eastern Finland. The results indicate that uncertainty in the paired-catchment analysis has important implications to the interpretation of the result.