The inventory of the terrestrial part of land-to-sea transects on Olkiluoto island in 2008 and the investigations of reedbeds surrounding Olkiluoto island carried out in 2007-2008

In 2008, six transects running from land to sea were established on Olkiluoto Island, where soil and vegetation properties were studied at the transition zone and land- and seawards from the waterline. This Working Report presents results of the inventory on the land side. The soils varied from very fine grained to stony till soils and bedrock outcrops. This variation was reflected in the vegetation. In forested areas, the least diverse field layers were met in transect sections with sandy till soils or bedrock outcrops, where the canopies were already closed. Groves were situated on fine sand soils. The transition zone between sea and land differed from line to line and depended on soil properties, topography and degree of shelter. Human actions (e.g. various construction works) have greatly affected the land cover and soils. In addition to Olkiluoto, similar methodology was applied on shorelines of two so called reference lakes (Koskeljaervi and Lutanjaervi). Furthermore, this Working Report describes reedbed inventories carried out on Olkiluoto on 2007 and 2008. Reed was met on gyttja, clay, till and stone bottoms. The extent and vitality of the reedbeds varied relatively much, depending on the soil type and degree of shelter. In water, widest reedbeds were located by the bridge connecting the island to mainland. On the terrestrial side, competitive reed was met very far from the shoreline in a few large bays with clay soil. Summer cottages and dredging had affected the natural extent of reed. (orig.)