Restoration induced long‐term vegetation change in oligotrophic peatlands

Abstract

Ecological restoration of forestry-drained peatlands is an increasingly acknowledged mean to halt the biodiversity loss, yet little is known on the long-term responses of vegetation—a key factor in judging the success of various restoration measures. In this study, we follow long-term succession in vegetation composition from a year before through 11 years after peatland rewetting by ditch filling. Tree harvesting as a part of restoration was conducted by removing the whole trees or stems only. For both restoration approaches, the restoration trajectory of vegetation was non-linear, and the recovery time differed between plant functional groups. We first observed an initial loss of species, followed by increases in species indicative of undrained peatlands and an increase in trait heterogeneity. Additionally, we observed that sedges responded to restoration faster than Sphagnum mosses. Synthesis and applications: Here we show that restoration increases the resemblance to undrained peatlands, with little differences between the tree harvesting methods. We suggest that Sphagnum moss cover could be used in monitoring the success of restoration of nutrient poor peatlands. Our results highlight the necessity of long-term monitoring. The difference between strip and near former ditch lines showed spatial variability long after the restoration, which should be accounted for in monitoring.