Histosol as an ecologically active constituent of peatland: a case study from Estonia

Abstract

This study clarifies the area distribution of Estonian peat soils by three factors: main peat soil groups, peat thickness and peat decomposition degree. A digital soil map (1:10,000) and supplementary database were used for summarizing the distribution of peat soils. From the combined database with 859,701 polygons the soil mapping unit code, formula of soil texture (including peat) and formula of epipedon fabric were compiled using the MapInfo software. Peat soils form altogether 10,038 km2 or 23.5% of the total Estonian soil cover. From the peat soils the fen soils form 59.0%, bog soils 21.7% and transitional bog soils 14.7%. 45% of peat soils are well, 26% moderately and 29% slightly decomposed, by the peat thickness 13% are very shallow, 21% shallow and 66% thick. The general ecological characterization of peat soils and their mutual relationship with plant cover are given for the main peat soil taxa. The dominant natural ecosystems formed on peatlands are: (1) mixed birch, alder, spruce and pine forests on thin ( 100 cm) slightly decomposed oligotrophic bog soils. The accumulation of organic carbon in peatlands soil cover (0–50 cm) totals 269.4±12.7 Tg and in epipedon layer (as superficial part of soil cover; 0–30 cm) 129.9±5.8 Tg. The former is sequestrated into 543.7 Tg of peat, which forms 22.9% of the total Estonian peat resources (2.37 Pg).