Estimating the soil subsidence and carbon losses from long term anthropogenic use of peatlands: A case study on a Danish raised bog

Abstract

Upon drainage, peatlands subside and release stored carbon (C) into the atmosphere. However, little is known about the magnitude of the total, physical and oxidative subsidence (TS, PS and OS) over long historical periods and the past contribution of humans to the degradation observed in contemporary times. Lack of historical subsidence data may hinder contemporary restoration efforts, highlighting the need for insights into past degradation to inform current management practices. Therefore, the present study aims to assess the effect of human activities on the degradation of a raised bog in Denmark in terms of the TS, PS, OS and the C lost between 1880 and 2010 using legacy datasets. The results indicate that 84 % of the bog had been drained by 1997. The TS was 1.6 m on average with a rate of 1.8 cm y-1. A total of 117 million m3 of peat was lost in the 130-year period. The PS was most important shortly after the start of drainage while OS gained importance in the long term. Up to 540 t ha-1 of C-stock was lost at a rate of 6 t ha-1 y-1, translating to 22 t ha-1 y-1 in carbon dioxide equivalents. Therefore, the bog represents a C source in contemporary times, which necessitates targeted and positive management interventions that favour peat growth and C accumulation.

Keywords

• co2
• drainage
• human impacts
• peatland cultivation
• peatland degradation
• store vildmose