Vegetation Composition and Carbon Dioxide Fluxes on Rewetted Milled Peatlands — Comparison with Undisturbed Bogs
2021
Purre, Anna-Helena | Ilomets, M.
Rewetting is the most common restoration approach for milled peatlands in Europe, with the aim of creating suitable conditions for the development of peatland specific plant cover and carbon accumulation. Therefore, it is important to determine if milled peatlands become functionally and structurally similar to their undisturbed counterparts. We measured plant functional type (PFT) cover and biomass, bryophyte production and CO₂ fluxes on three rewetted peatlands in Estonia restored 4, 15, and 35 years before the measurements and compared observations at rewetted sites to two nearby reference bogs. We hoped to better understand whether structure and function return at rewetted sites over time. Differences in vegetation composition and CO₂ fluxes between the sites were greater for rewetted than undisturbed sites. The most recently rewetted site was mainly covered in bare peat and Eriophorum vaginatum and was a CO₂ source. On the rewetted site of 15 years, Sphagnum was present in addition to ombrotrophic sedges, and in the rewetted site of 35 years, lawn-hollow microtopography is starting to develop with various PFTs. Both of these sites were CO₂ sinks. Lawn Sphagnum was abundant on the two older rewetted sites, and was connected with CO₂ sink functioning in the rewetted sites. Still, hummock Sphagnum species, which were present in undisturbed bogs, were absent from all of the rewetted sites. With time, CO₂ fluxes, microtopography and vegetation develop after rewetting in the direction of undisturbed bogs, while vegetation composition still differs from the reference sites even 35 years after rewetting.
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