New insights on habitat preferences of the Northern Emerald dragonfly (Somatochlora arctica)

Abstract

Odonates are widely considered to be bioindicators of freshwater habitat quality. Somatochlora arctica (Corduliidae) are commonly found across Eurasia, predominantly North and Central Europe, but in the UK, they is listed as near threatened and currently restricted to few areas of Scotland despite a large, potential habitat availability. Across their range their larvae are commonly found in Sphagnum-filled bog pools nearby coniferous woodlands, but detailed data on their habitat preferences are limited which inhibits conservation efforts. We designed a survey targeting 3 known, but geographically distinct, S. arctica locations in Scotland: Abernethy & Loch Garten National Nature Reserve (NNR), Beinn Eighe NNR and Flanders Moss NNR to evaluate how different environmental factors (e.g. water depth and chemistry, bryophyte species and coverage, woodland distance, etc.) affect the presence and abundance of S. arctica. We found pools that were located far from woodlands (i.e. >50m) had a lower presence of S. arctica and that S. arctica was mostly found in pools with high densities of Sphagnum coverage (> 90%). Our results highlight the importance of nearby woodlands and Sphagnum quantity and potentially species type for different life stages of S. arctica. Future conservation projects should consider the proximity of woodland to current and restored S.arctica sites or promoting expansion of surrounding natural woodland patches in order to benefit S.arctica and potentially other odonates.