Changes in satellite‐derived spectral variables and their linkages with vegetation changes after peatland restoration

Remote sensing (RS) can be an efficient monitoring method to assess the ecological impacts of restoration. Yet, it has been used relatively little to monitor post‐restoration changes in boreal forestry‐drained peatlands, and particularly the linkages between changes in RS and plant species remain vague. To understand this gap, we utilize data from the Finnish peatland restoration monitoring network spanning 150 sites and a 10‐year post‐restoration monitoring period. We employ Bayesian joint species distribution models (Hierarchical Modeling of Species Communities) to study (1) the changes in optical Sentinel‐2 and Landsat satellite spectral signatures, (2) whether the RS variables improve predictions of vascular plant and moss species and functional type occurrence and cover, and (3) what kinds of associations exist between RS variables and plant species or functional types. Our results show that peatland restoration increases the reflectance of red and near‐infrared (NIR) bands in sparsely treed pine mire forests and open mires but not in densely treed spruce mire forests. Impacts on other tested RS variables consisting of moisture and greenness indices are less clear. Additionally, RS variables increase species‐ or functional type‐specific predictive power only modestly, and there are few clear links between the changes in RS variables and species or functional‐type occurrence and cover. We suggest that red and NIR reflectance can be used as satellite‐based indicators for peatland restoration success and further studies are required to develop usable methods for detecting species‐specific changes with RS.