The human dimension of pedogenesis and soil organic matter accumulation at grazed and pristine sites in the High Andes

点击翻译按钮获取中文摘要

Human impact on the environment by land use has globally induced major changes in soil development and caused severe losses of carbon from terrestrial ecosystems. Besides slow net changes, soil organic matter is one of the most important ecosystem carbon reservoirs due to the high stocks. Current evidence suggests that the size of the source or sink of soil for atmospheric carbon dioxide is linked to soil properties, which evolve from pedogenetic processes. However, land use and carbon sequestration have not yet been properly linked with pedogenesis. One reason is the lack of suitable reference sites that can clearly be assigned as pristine, but offer conditions comparable to sites used by humans. We have identified such pristine sites in the Cusco region of the Peruvian Andes on remote mountain ledges. These are only accessible with mountaineering equipment but are close to sites which have been under extensive grazing management for several millennia. We hypothesise that (a) Land use and associated vegetation change affected soil genesis, leading to different classification units of pristine and disturbed soils and (b) land use and altered soil genesis changed the relative importance of the particular mechanisms stabilising soil organic matter. To address these hypotheses, soil classification and soil development indices will be used and linked to the distribution of soil organic matter among fractions that are stabilised by different mechanisms. Linking aspects of soil genesis with soil organic matter stabilisation will enhance our understanding of the human impact on carbon sequestration and may help to enhance mitigation strategies for land use change induced losses of carbon to the atmosphere.