Patterned fen development in northern Scotland: Hypothesis testing and comparison with ombrotrophic blanket peats

Patterned fens are part of the diverse Holocene peatland landscape of the Flow Country, northern Scotland. Their present vegetation and morphology allies them with boreal systems in Scandinavia and North America. However, previous work has shown that their mode of formation is rather different and has suggested a developmental model in which the poor fens have formed only recently and have arisen as a result of local hydrological change. These ideas are tested here by morphological, stratigraphical and macrofossil studies on three additional patterned fens covering a wider geographical and ecological range. Two sites corroborate the hypotheses of the earlier study, and one site which refutes the earlier findings can be shown to be dependent on different topographic controls. A comparison of two patterned fens with an ombrotrophic mire site in the same area shows that hydroseral processes dominate the early development of individual components of the mire complex. The time of initiation of patterned fens coincides with increasing surface wetness on the ombrotrophic mire. This may be due to climatic change and/or the coalescence of the constituent parts of the present integrated blanket mire system. The hydrological changes arising from this led to the emergence of the springs that currently supply the patterned fens with their water and elevated nutrient levels. The study supports the idea that landscape-scale research and conservation are essential for the understanding and hydrological integrity of blanket mire landscapes such as the Flow Country.