Peatland restoration in Norway – evaluation of ongoing monitoring and identification of plant indicators of restoration success

Norway launched a national action plan on wetland restoration in 2016. So far, 90% of the restoration effort has been on peatland restoration, with about 140 mires restored so far. There are three main restoration goals stated in the action plan: 1) Limit greenhouse gas (GHG) emissions, 2) climate adaptation, and 3) improve ecological condition. Quantifying the outcome of the restoration actions is necessary to evaluate whether the goals of the action plan are met. A vegetation monitoring protocol was suggested before restoration started and has been implemented at five restoration sites. As the peatland restoration effort in Norway is increasing, it is timely to evaluate if the data currently collected can measure peatland restoration outcomes. We evaluate the monitoring protocol based on statistical analyses of the data collected at two sites, describe how indicator species can be identified using generalized composition data used as the basis for classifying habitats in Norway (EcoSyst framework), and suggest the way forward for peatland restoration monitoring in Norway. Data collected according to the monitoring protocol can document changes in species composition at restoration sites but has limitations when the ecological complexity at the sites increases and reference sites are unavailable. We argue that adjusting the monitoring protocol will: 1) Facilitate alignment with existing peatland research; 2) connect better with monitoring programs where data is collected applying EcoSyst framework principles; and 3) enable upscaling to cover the wide variation emerging in peatland restoration.

Methods
Data was collected at two sites: Kaldvassmyra and Hildremsvatnet, both in Trøndela, Norway. A pinpoint intercept method was used to collect data along permanent transects. Transects at Kaldvassmyra were 50–80 m long, with the midpoint placed in a former ditch and the far ends of the transects reaching intact parts of the peatland. At Hildremsvatnet all transects were 50 meters long and they cross multiple, parallel ditches. Four transects were established before restoration at both sites, and a fifth transect (reference) was established at Kaldvassmyra in 2021. At Hildremsvatnet, all mires had been ditched and no reference area was available for establishing a reference transect. Data was collected before and after restoration at both sites, and a third time at Kaldvassmyra, as the site was restored prior to Hildremsvatnet.

Species data was recorded in 2.5 m segments (hereafter called species lines) spaced by 10 m intervals laterally along the transects, with the first species line starting at meter 0. We used a point intercept method to record data every 10 cm: A rod was held vertical to the ground and all species touching the rod were recorded. A species was only recorded once at each point, even if it touched the rod at several places. Species names follow the Species Nomenclature Database of the Norwegian Biodiversity Information Center.

Scripts of statistical analyses are available from GitHub: https://github.com/marijokerud/Peatland-restoration-in-Norway.git