High northern latitudes are increasingly exposed to the combination of extreme winter climate and deposition of long-distance dispersed nitrogen pollution. The nature in the north is vulnerable, and these combined pressures may over time drive changes in plant composition and carbon uptake, according to Bioforsk.
We have found that unstable winters can have very negative effects on overwintering of cultivated grassland with large repercussion on forage yields the following summer, says Marit Jørgensen, researcher at Bioforsk. Especially conditions leading to accumulation of ground ice have detrimental impacts on plant survival in such agro-ecosystems. But there is a large variation both between species and cultivars in how they cope with such unstable winter conditions, and probably even more variation in species of natural ecosystems, says Jørgensen.