Nutrient limitation in boreal rich-fen vegetation: A fertilization experiment

Abstract

Rich-fen vegetation influenced by hay-making in the Solendet Nature Reserve, Central Norway, was fertilized with N, P and K in a full-factorial fertilization experiment to investigate the nutrient limitation of plant growth at both community and species levels. Above-ground biomass, shoot density and nutrient concentration were measured in several species and groups of species at three sites after two years of fertilization. At the community level, the results indicate mul- tiple limitation by N and P in the two least productive rich-fen communities: one characterized by small sedges and herbs, and the other by high abundance of Menyanthes trifoliata and tall sedges. Increased nutrient availability had no effect on a more highly productive, tall-growing, spring-influenced com- munity, indicating no nutrient limitation. The results at the species level correspond well with those at the community level, indicating multiple limitation by N and P in most of the dominant and sub-dominant species. However, P seems to limit growth more than N in Succisa pratensis, and N seems to limit growth more than P in Carex panicea. Furthermore, Eriophorum angustifolium seems to be limited by K. The results did not show which nutrient limits the growth of Carex dioica, C. lasiocarpa and Trichophorum cespitosum. Indica- tions that growth in low-productive, boreal rich-fen communi- ties is generally limited by P was not confirmed.