Analysis of non-cellulosic polysaccharides helps to reveal the history of thick organic surface layers on calcareous Alpine soils

Background and aims

We investigated the potential of non-cellulosic polysaccharides (NCP) as biomarkers to identify the plant types that dominate present and past litter input into organic surface covers on calcareous Alpine soils and to reveal historic vegetation changes.

Methods

At two sites in the Alps, NCP monomers were quantified in different organs of site-dominating plants, the Oa horizon of four Folic Leptosols, and different sections of thick organic surface layers of four Folic Histosols on calcareous bedrock.

Results

The dominating plant types at our study sites differ markedly in their NCP composition and (galactose + mannose)/(arabinose + xylose) GM/AX] ratio (grasses and sedges: 0.2; dicots Fagus and Vaccinium: 0.2–0.6; conifers Abies, Picea, Pinus: 0.7–2.4; mosses: 5). For all except one soil, the NCP signature of the uppermost Oa horizon reflects the present vegetation. For all Histosol O horizons, NCP signatures indicate a dominance of conifer litter throughout their development (up to 1,500 years). Different NCP and GM/AX depth profiles reflect specific patterns of O layer genesis.

Conclusions

NCP and GM/AX depth profiles in organic surface covers of soils provide important information about dominating litter sources in the past and can be valuable tools to reveal historic vegetation and/or land use changes.