Response of Tipulidae (Diptera) populations to grip-blocking at a low altitude blanket peatland: implications for ecosystem resilience in the context of climate change

Abstract

Grip-blocking is an extensively deployed yet understudied peatland restoration technique that involves blocking artificial drainage channels (grips) in order to raise water-table levels. Tipulids [Craneflies] represent a functionally important species of peatland ecosystems and constitute an essential prey item for breeding waders. As larvae, peatland tipulids require year-round wet peat, are many species are extremely vulnerable to desiccation in drought. Grip blocking has been identified as a potentially vital mitigation strategy for breeding wader conservation in the context of climate change by increasing tipulid abundance.

Using emergence traps, this research compared tipulid abundance within peatland soils adjacent to blocked and unblocked grips, together with soil moisture and vegetation data. Uniquely, the study also compared tipulid abundance, community composition and relative biomass at grips which have been blocked for varying lengths of time.

Significant covariations were identified between soil moisture, vegetation communities and tipulid community compositions. Larger tipulids species were positively associated with high soil moisture, which has important consequences for prey biomass for predatory birds, in addition to the potential for tipulid size to act as a potential environmental indicator.

Among-site variations attributed to topographical differences appear to over-ride any positive influences of time since restoration, which highlights the importance of site-specific management and post-restoration monitoring.

Results indicate that a heterogeneous mosaic of hummocks and pools would allow for tipulid species diversity, which may reduce risks of Tipulidae population crashes during drought.

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