AbstractsBiology & Animal Science

Drainage to increase timber production has drastically decreased the area of undrained spruce swamp forests in northern Europe. In restoration by rewetting, drainage ditches are blocked to restore the original hydrology and, ultimately, the structure, function and ecosystem services of undrained boreal spruce swamp forests. This study quantifies the restoration success of rewetting regarding plant community composition, moss community carbon assimilation potential, Sphagnum biomass production and surface peat biogeochemistry, and aims to determine the main controls of success. The study sites comprised 18 rewetted, nine undrained and nine drained spruce swamp forests in southern Finland, complemented by sites in the umava Mountains, Czech Republic. Drainage had taken place decades prior; the rewetted sites varied in their rewetting age from 1 to 15 years. The results show that rewetting has to raise the water table above a threshold to initiate any changes in the drained ecosystem. If the threshold is crossed, the changes that occur will be rapid. Two strands of development emerged throughout the different components of the ecosystem: development towards the undrained reference state and development towards a new direction, different from both the undrained and the drained state. Rewetting created favourable conditions for Sphagnum photosynthesis. Sphagnum mosses recovered in cover and biomass production rapidly. The new growth started the accumulation of the porous surface organic matter layer characteristic of mires, which increased microbial decomposition activity in the surface organic layer towards undrained levels. Meanwhile, rewetting applied on the compacted, physicochemically altered peat created wet, unstable hydrological conditions, which increased the cover of opportunistic plant species in the understory and caused high NH4 mobilization and CH4 production in the surface organic layer. Demanding spruce swamp forest species were lacking at the rewetted sites, but rewetting was successful in restoring the common species and directing the ecosystem towards mire-like functioning. Korvet ovat puustoisia, kuusivaltaisia soita. Luonnontilaiset boreaaliset korvet ovat arvokkaita luonnon monimuotoisuuden keskittymiä, hiilen varastoja ja hyödyllisiä orgaanisen aineksen suodattajia valuma-alueen vesistä ennen niiden päätymistä vesistöihin. Aiemmin yleisten korpien määrä on Pohjois-Euroopassa vähentynyt rajusti viime vuosikymmeninä, pääasiassa metsätaloudellisten ojitusten vuoksi. Ennallistamisessa vedenpinta nostetaan uudelleen tukkimalla kuivatusojat. Tavoite on palauttaa luonnontilaisen korven rakenne ja toiminta ja sitä kautta korven tarjoamat hyödyt. Tämä tutkimus mittaa rakenteen ja toiminnan palautumista ekosysteemin eri osa-alueilla ja palautumiseen vaikuttavia tekijöitä. Tutkittavina ovat korven pohjan kasviyhteisörakenne, rahkasammalten yhteyttäminen ja kasvu sekä pintaturpeen biogeokemia. Tutkimuskohteina toimivat 18 ennallistettua korpea, joissa ojat on tukittu 1−15 vuotta aiemmin, sekä yhdeksän…