Carbon concentrations and stocks in forest soils of Europe

This study presents the results of a series of evaluations of a continent-wide soil database (EU/UN-ECE Level I) with the aim to estimate baseline soil carbon concentrations and stocks The methodology Included the biogeographic stratification of soil carbon measurements throughout Europe using climatic zones derived from the Soil Regions Map of Europe. The presented stock estimates range from 1.3 to 70.8 t C/ha for the O-layer, and from 11 3 to 126.3 t C/ha for the mineral soil 0-20 cm (Germany. 0-30 cm) (5 and 95 percentiles) Histosols were excluded because of methodological differences and data gaps. When looking at the median values of the strata investigated, relationships were found For example, carbon stocks in the O-layer of sandy soils are distinctly higher than those of fine-textured soils. However, the variability is so high that some of these relationships disappear. For example in western and central Europe. the level of carbon stocks in the mineral soil between shallow soils (Leptosols) and more deeply developed soils (Podzols and Cambisols) do not differ very much It was also found that just the investigation of topsoils is not sufficient to understand the regional pattern of organic matter in forest soils - unless the subsoil becomes Included as well It is hypothesized that for Europe, the Impact of site factors such as climate, texture and relief are difficult to extract from such a database if the data are only stratified according to macro-climatic areas It has to be considered that the effect of systematic error in the database is quite large (but cannot be identified on the level of the current data availability) In order to receive a first impression of the landscape-level distribution of carbon, a map of carbon concentrations in the topsoil was generated. The results support the relationships found between carbon stocks and site factors, such as climatic zones and soil type. Compared to the much lower carbon concentrations of agricultural soils, the results demonstrate clearly the importance of forest soils for the terrestrial carbon cycling in Europe (C) 2010 Elsevier B.V All rights reserved