Hay crop of boreal rich fen communities traditionally used for haymaking

Abstract

The traditional use of fen areas for hay production had been extensive in boreal Europe, but few studies have investigated the hay crop of different fen plant communities. We studied the hay crop from upper boreal (sub-alpine) rich fens using data from 81 permanent plots over more than 30 years in one coastal (oceanic) area and one inland (continental) area in central Norway. Permanent 12.5 m2 plots were mown with a scythe every year, every 2nd year or every 4th year. A large majority of the plots under study were lawn and open margin communities classified within or related to the phytogeographical order Caricetalia davallianae. There was no difference in the hay crop between the study areas in these communities, indicating that biomass production is about the same in ecologically similar rich fens that share the same dominant species. The first hay crop (including litter) from lawn communities was about 160 g/m2 after 20–30 years of abandonment. Regular mowing every second year reduced the hay crop by more than 30 %, and stabilized it after three mowings. The hay crop decreased with increasing mowing frequency; in lawn and open margin communities, mowing every 4th, every 2nd and every year yielded on average 140, 113 and 65 g/m2, respectively. In earlier times, it used to take farmers about 10 days’ work to harvest one hectare. Thus, the traditional practice of mowing every 2nd year was efficient in terms of the hay crop and labour input, and the quality of the hay was improved due to a lower litter fraction. Keywords Biomass · Boreal brown-moss fen · Caricion davallianae · Long-term experiment · Mowing · Permanent plot · Semi-natural vegetation