A 5-year study of the impact of peatland revegetation upon DOC concentrations

Abstract

Peatlands are among the largest long-term soil carbon stores on the globe, but their degradation can lead to significant carbon losses. Therefore, restoration of peatlands has received considerable attention but the impact of revegetation upon critical water quality parameters has not been assessed. In this paper we consider a 5-year study of three restored sites in comparison to both an unrestored, bare peat control and to a vegetated control that did not require restoration. The soil porewater dissolved organic carbon concentration (DOC) was measured (6 replicates) for each restoration treatment and each control. The soil water measurements were made in the context of measuring the depth to water table; soil water pH and conductivity; and DOC concentration in surface runoff for the same restored and control treatment. The study showed that the average soil porewater DOC concentration on the restored sites rose significantly over the 5. year study representing a 34% increase relative to the vegetated control and an 11% increase relative to the unrestored, bare control. Soil pore water concentrations were not significantly different from surface runoff DOC concentrations, and therefore restoration as conducted by this study would have contributed to water quality deterioration in the catchment. However, had water table restoration been conducted alongside revegetation then a significant decline in DOC concentrations could have been realised.