Cutaway Peatland Fertilisation With Wood Ash Leads to More Than a Tenfold Increase in Plant Biomass Accumulation

Afforestation is one of the widely used methods of reclamation in cutaway peatlands where spontaneous revegetation is not feasible, but fertilization or liming is usually required to encourage the development of vegetation cover. Wood ash application increases planted tree biomass, but the role of spontaneously incoming species in early‐stage biomass accumulation is lesser known. The amount of below‐and aboveground biomass accumulation was evaluated in relation to the drainage ditch position (2 or 9 m from the ditch edge) and the amount of wood ash applied (0, 5, 10, or 15 megagrams ha −1 ) three years after fertilization. The biomass accumulation, species richness, and plant carbon and nitrogen ratio were positively impacted by wood ash treatment, but biomass allocation was species dependent: for all tree and herbaceous species with individual root systems, the proportion of biomass accumulated in roots was higher in the unfertilized group, but for Phragmites australis with a clonal root system, it was contrariwise. The application of 10 Mg ha −1 wood ash was the most productive, with an average of 485.0 g/m 2 total plant dry biomass accumulation next to and 301.3 g/m 2 further from the drainage ditch, compared to the unfertilized 36.8 g/m 2 (2 m from ditch) and 13.9 g/m 2 (9 m from ditch). During the initial vegetation establishment, herbaceous species comprised the majority of the biomass, primarily graminoids.