Recent changes in boreal aapa mires indicated by CPIsnow model and Landsat time series

Patterned fens (aapa mires) are important part of boreal landscape. Their distribution is controlled by climate and local hydrological conditions. In order to assess the changes and stresses climate change and land use may cause in these ecosystems, we modelled the past and future hydrology of twelve aapa mires in different parts of Finland. The study area extends from the southern to northern boreal zone.

Mire catchments were delineated with the help of a digital elevation model. Wet minerotrophic areas (flarks) in the centers of aapa mires were traced from aerial images with numerical methods. Runoff modelling was done for the period 1962–2099 with a conceptual model ‘CPI snow’ using gridded temperature and precipitation data from historical weather records as well as predicted values based on climate scenarios.

The results clearly indicate changes in hydrological conditions of aapa mires. In particular, timing and volume of spring peak runoff after snowmelt are affected. It is probable that the changes influence aapa mire wetness, vegetation, and eventually survival and distribution. We search for evidence of these changes from remote sensing time series (Landsat) from 1980s to present. Possible implications of changes in northern peatlands include loss of biodiversity and changes in carbon cycle.