PEAT VOLUME LOSS IN THE DITCHES OF NORTHERN MINNESOTA

Peatlands play an important role in carbon (C) storage and are estimated to contain 30% of global soil C, despite occupying only 3% of global land area. Historic management of peatlands has led to widespread degradation and loss of important ecosystem services including C- and fresh water storage. Legacy drainage features in the peatlands of northern Minnesota were studied to assess the volume of peat that has been lost in the ~100 years since drainage. Using high-resolution Light Detection and Ranging (LiDAR) data, we measured elevation changes along the margins of legacy ditches to model preditch surface areas, which were used to calculate peat volume loss. We established relationships between volume loss and site characteristics from existing Geographic Information Systems (GIS) datasets and used those relationships to scale volume loss to the length of peatland ditches in northern Minnesota. It is estimated that 165.3 ± 8.6 million m3 of peat have been lost throughout peatland ditches that extend almost 4,000 km. Peat loss on the upslope side of the ditch was significantly less than peat loss on the downslope side of the ditch (P-1 yr-1, respectively. Our framework can be used as a decision support tool to guide preliminary management decisions with the objective of protecting C on natural Minnesota landscapes.