From Haymaking to Wood Production: Past Use of Mires in Northern Sweden Affect Current Ecosystem Services and Function

Mires form a large part of the boreal Swedish landscape and are important for biodiversity and natural ecosystem processes. Historically, mires also played a key role for the expansion of agricultural practices, and later to create new forest land, but knowledge is limited on how the land use has affected the current ecosystem services and functions of mires. In this case study from northern Sweden, we have combined historical maps with remote-sensing data to analyze the use of mires over time. Here, 22% of the mire area has been used for hay harvesting, an activity that peaked in the late 1800s. Later, about 3% was reclaimed for intensive agriculture. Drainage to enhance wood production followed in the 1940s, and about 40% of the original mire area is currently forested. The most productive mires have been relatively more affected by human measures. We suggest that this past land use has legacy effects on several ecosystem services. Haymaking likely had positive effects on biodiversity, but may have negatively influenced carbon sequestration. Reclamation led to habitat loss and likely less carbon sequestration. Drainage to promote forest growth generally lowered the ground water level, which in turn enhanced peat decomposition and subsequently released CO₂. However, if tree growth outpaces peat decomposition, drainage could increase carbon sequestration. The overall carbon balance is hence influenced by past management regimes, which implies that past human use must be taken into account when considering the role of mires in providing ecosystem services.