Phyto‐ and necromass above and below ground in a fen

Abstract

Few investigations deal with the subterranean phytomass in fens (minerotrophic peatlands), their results differing widely. This study was carried out in a “rich fen” in central Sweden, and involved excavation of peat monoliths, depth‐sectioning and hand‐sorting as to species, type of organ, and living or dead condition. The below‐ground living phytomass was large, over 4 kg m−2 in each of two sample plots, being no <97–96% in the dominants, Carex limosa and C. lasiocarpa, 89% on average in Menyanthes trifoliata, and c. 93% for all species. Carex limosa had its rhizome maximum slightly higher than C. lasiocarpa, but a greater part of its roots penetrated deeper. For Menyanthes, also net annual production above and below ground was estimated. The subterranean phytomass decreased with depth, but living roots were found even at 42 cm. The recognizable necromass did not decrease with depth. These recent constituents would render a very unequal age to the peat. The imbalance between the small green aerial phytomass and the much greater subterranean phytomass was emphasized. It could be related to a relatively very great translocation of photosynthates from above to below ground, and/or to longevity of below‐ground organs, the latter at least in Menyanthes.