Multidisciplinary assessment of European aapa mire ecosystem changes

Abstract

Fens prevail in north-boreal to subarctic regions, while bogs are more common in hemiboreal to middle boreal zones. In concordance with this pattern, the expected north-ward movement of climatic ecotones theoretically includes the transformation of northern fens into bogs. Such a major ecotone shift is plausible because it conforms to the typical pattern of bog development, as most bogs have been fens in their early phases of development. Several recent case studies have suggested that critical phases of the fen-bog transition (i.e. ombrotrophication) may take place rapidly within few decades.

The main goal of SHIFTMIRE is to identify changes in main ecosystem structures during recent decades in aapa mires, an ecotone mire complex type with restricted climatic-zonal occurrence in the north-boreal zone. Ecosystem-scale structural changes can affect important functions like carbon sequestration in peat and have feedback in the climate system. The main hypothesis is that northern ecosystems are in an onset response to climate change and regionally to hydrological disturbances that may lead to ecosystem shifts, corresponding to the threshold state of the Red List assessment protocol of IUCN. We ask if aapa mire ecosystems are changing and can climate and hydrological modelling explain and predict their trends?

In aapa mires, the well-known succession pattern of fen-bog transition is the main theoretical basis of ecosystem change, a phenomenon observed to have taken place within past decades in recent case studies. We aim at testing the use of quantitative proxy results in the Red List of ecosystems protocol and connected risk analysis modelling. Aapa mires are an excellent system for developing and testing of ecosystems modelling, given the advanced understanding of ecological drivers and mire dynamics, a strong capital of ecological time series data and the threats posed by future climate and land use change.

We apply a multidisciplinary approach involving vegetation and peat sampling, remote sensing and modelling of changes in hydrology and vegetation of aapa mires over recent decades. Sampling will first focus on detailed case studies in Finland and subsequently cover a geographically representative sample of aapa mires of NW Europe. Novel methods of hyperspectral imaging of dated peat profiles will be developed for detecting plant material composition of peat. We proceed to climate-model based prediction of potential changes of aapa mires in the next 100 years and make assessment of their ecosystem Red List status.