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. Today, on the Sanetti Plateau in the Bale Mountains of Ethiopia, onlyfragmented patches of Erica species can be found at high altitudes (between 3900and 4200 m a.s.l.). However, it is hypothesized that during the later part of the last glacial period and theearly Holocene the plateau was extensively covered by Erica shrubs. Furthermore,it is assumed that the vegetation was later heavily destroyed byhuman-induced fire and/or climate change phenomena. The objective of thisstudy is to contribute to paleovegetation reconstructions of the SanettiPlateau by evaluating the potential of stable isotopes ( δ13 Cand δ15 N) and sugar biomarkers for distinguishing the dominantplant species, including Erica, and the soils below the plants. In a companionpaper (Lemma et al., 2019a) we address the same issue by evaluatinglignin-derived phenols and leaf-wax-derived n -alkane biomarkers. The stable carbon ( δ13 C) and nitrogen ( δ15 N)isotope values of the plant samples range from −27.5   ‰ to −23.9   ‰ and −4.8   ‰ to 5.1  ‰, respectively.We found no significant δ13 C and δ15 N differencesbetween the dominant plant species. Mineral topsoils (A h  horizons)yielded more positive values than plant samples and organic layers(O layers), which reflects mineralization processes. Moreover, the δ15 N values became generally more negative at higher altitudes. Thislikely indicates that the N cycle is more closed compared to loweraltitudes. δ15 N maxima around 4000 m a.s.l. point to fire-inducedopening of the N cycle at the chosen study sites. Erica speciesyielded the lowest overall total sugar concentration (ranging from 58 to 118 mg g −1 ), dominated by galactose (G) and mannose (M). By contrast,Festuca species revealed much higher total sugar concentrations ranging from 104 to253 mg g −1 , dominated by the pentose sugars arabinose (A) andxylose (X). Although a differentiation between Erica versus Festuca, Alchemilla and Helichrysum is possible basedon (G  +  M)  ∕  (A  +  X) ratios, Erica cannot be unambiguously distinguished from allother plant species occurring on the Sanetti Plateau. In addition,plant-characteristic (G  +  M)  ∕  (A  +  X) sugar patterns change during soilorganic matter formation in the A h  horizons. This can be likelyattributed to degradation effects and soil microbial build-up of galactoseand mannose. In conclusion, soil degradation processes seem to render sugarbiomarker proxies unusable for the reconstruction of the past extent ofErica on the Sanetti Plateau, Bale Mountains, Ethiopia. This finding is ofrelevance beyond our case study.

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Chemotaxonomic patterns of vegetation and soils along altitudinal transects of the Bale Mountains, Ethiopia, and implications for paleovegetation reconstructions – Part 1: stable isotopes and sugar biomarkers