Tree species effects on soil organic carbon stocks and chemical properties of the topsoil in the arboretum of Tervuren
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- In the context of climate changes, forest management can improve the long-term storage of soil organic carbon by tree species selection. In literature, it is often reported that coniferous species are more likely to store a high quantity of SOC in the forest floor compared to broadleaves species. However, there is a lack of data about the impact of species on SOC stocks in the mineral soil. In the context of this master thesis, soil samples were collected in the arboretum of Tervuren in stands of 22 different species. The aim of the study was to identify a potential difference of SOC stocks in mineral topsoil between broadleaves and conifers. A second objective was to determine in which soil conditions SOC stocks were higher, and to relate these soil chemical properties to species traits. The results show higher SOC stocks in the forest floor and in the uppermost topsoil layer in conifers, due to OM accumulation. Besides, a relationship is established between high carbon contents and high contents of exchangeable Al, and by extend acidic conditions. By contrast, we observed no substantial impact of species on SOC stocks in the mineral topsoil below 5 cm. An explanation to this unexpected observation may rely on acidic conditions in the topsoil. Indeed, we suggest that topsoil conditions in the study area are unfavorable for earthworm activity and that might have an impact on SOC fluxes between the forest floor and the mineral topsoil, independently from species effect. This hypothesis needs to be confirmed by further investigation. It may be in line with the assumption in literature that conifers are more efficient to accumulate SOC than broadleaves species under unfavorable conditions, but not necessary in SOC stable pools.