From leaf to soil: n-alkane signal preservation, despite degradation along an environmental gradient in the tropical Andes

Teunissen van Manen, Milan L.; Jansen, Boris; Cuesta, Francisco; León-Yánez, Susana; Gosling, William D.

The relative abundance of inline-formulan-alkanes of different chain lengths obtained from ancient soils and sediments have been used to reconstruct past environmental changes. However, interpretation of ancient inline-formulan-alkane patterns relies primarily on modern plant wax inline-formulan-alkane patterns measured from leaves. Little is still known about how inline-formulan-alkane patterns, and environmental information therein, might be altered during the process of transfer from leaves into soil. We studied the inline-formulan-alkane patterns extracted from leaves, necromass, and soil samples from an altitudinal gradient in the tropical Andes to clarify if the inline-formulan-alkane pattern, and the local environmental information reflected, is altered as the plant source material degrades. We considered the (dis)similarity between inline-formulan-alkane patterns in soil, necromass, and leaves and specifically explored whether a temperature and/or precipitation signal is reflected in their inline-formulan-alkane patterns. The inline-formulan-alkane patterns showed degradation in soil as reflected by a reduced carbon preference index (CPI). The lower CPI in soils as compared to leaves and necromass was significantly correlated with temperature and precipitation along the transect, most likely because of increased microbial activity under warmer and wetter conditions. Despite degradation, all sample types showed a systematic shift in longer vs. shorter inline-formulan-alkanes when moving up the transect. Further examination revealed the systematic shift correlated with transect temperature and precipitation. Since transect vegetation is constant along the transect, this would appear to indicate the recording of a climatic signal within the inline-formulan-alkane patterns that is preserved in the soil, albeit that the correlation was weaker there. The study results warrant further research into a possible underlying causal relationship that may lead to the development of inline-formulan-alkane patterns as a novel palaeoecological proxy.

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Teunissen van Manen, Milan L. / Jansen, Boris / Cuesta, Francisco / et al: From leaf to soil: n-alkane signal preservation, despite degradation along an environmental gradient in the tropical Andes. 2020. Copernicus Publications.

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Rechteinhaber: Milan L. Teunissen van Manen et al.

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