Tardigrade communities in pristine, drained and restored pine mire forests

Restoration has become one of the key measures in improving the state of biodiversity. However, restoration outcomes are in many cases not well understood, and species communities have not been monitored long enough to determine whether they can or cannot recover completely to the pristine reference state. So far, it is particularly poorly known how the communities of microscopic fauna vary within and between pristine, drained and restored peatland habitats. We collected 270 moss samples from a replicated restoration experimental set up to study whether tardigrade communities differ between pristine, drained and restored pine mire forests. In addition, we estimated the associations between tardigrade genera and the moss type they live in. We found a weak pattern of tardigrade occupancy probability being lower in drained and restored sites than in pristine sites. Furthermore, some tardigrade genera were less likely to occur at the drained and restored (11 to 16 years after restoration) sites when compared to pristine sites, although no significant differences in community compositions between treatments were found. We found notable within site variation, which is indicative of high patchiness in tardigrade distribution. We also found strong associations between some of the moss types and tardigrade occurrences. Therefore, tardigrade occurrence seems to be more linked to microhabitat changes, such as mosses, than treatment of the sites. Although the differences between treatments were small, our results show that drained and restored pine mire forests may provide less suitable habitat for tardigrades than the pristine sites do. Favorable habitat conditions for tardigrades in these ecosystems are likely to arise from combinations of large- (e.g., hydrology) and small-scale (moss type) environmental variables that are both affected by drainage and restoration.