Biochemical evidence for minimal vegetation change in peatlands of the West Siberian Lowland during the Medieval Climate Anomaly and Little Ice Age

Abstract

Peatland vegetation is controlled primarily by the depth of the water table, making peat paleovegetation a useful climate archive. We applied a biochemical approach to quantitatively estimate the plant sources of peat carbon based on (1) neutral sugar compositions of Sphagnum, vascular plants, and lichens and (2) lignin phenol compositions of vascular plants. We used these biochemical indices to characterize vegetation change over the last 2000 years in four peat cores from the West Siberian Lowland (Russia) to investigate climate change during the Medieval Climate Anomaly and Little Ice Age. The vegetation was dominated by Sphagnum in all four cores, but was punctuated by several rapid but transient transitions to vascular plant dominance in the two cores from the southern West Siberian Lowland (<60°N latitude). Lichen contributions were evident at the end of the Medieval Climate Anomaly and during the Little Ice Age in the two cores from northern West Siberian Lowland (>60°N), possibly indicating permafrost development. However, there was no evidence for sustained vegetation change in response to either climatic event in cores from southern West Siberian Lowland. This suggests that these climatic events were relatively mild in the southern West Siberian Lowland, although the sensitivity of bog plant communities to climate change remains poorly understood.

Predicting Dissolved Lignin Phenol Concentrations in the Coastal Ocean from Chromophoric Dissolved Organic Matter (CDOM) Absorption Coefficients

“…Only samples from the Ob estuary deviated significantly from the general relationship, and were enriched in P phenols relative to a g (285). However, this enrichment in P phenols was apparent and most likely originated from elevated levels of peatderived sphagnum acid typically found in the Ob watershed, and their subsequent conversion into P phenols during the oxidation of lignin (Amon et al, 2012;Philben et al, 2014). The relationship became progressively less robust with V phenols (R 2 > 0.925) and S phenols (R 2 > 0.893).…”

“…The positive residuals in the Chukchi Sea (all collected in summer) were potentially related to a higher background of autochthonous CDOM in these productive waters (Shen et al, 2012a), whereas those of the Ob estuary are consistent with significant contribution of non-lignin CDOM from Sphagnum sp. peats (Amon et al, 2012;Philben et al, 2014). The positive residuals in the South Carolina coast samples are likely related to contributions from the tidal marshes, which have been shown to have distinctive CDOM chemical and optical properties (Tzortziou et al, 2008).…”

Temperature, oxygen, and vegetation controls on decomposition in a James Bay peatland

“…Relationship between the botanical composition and extent of decomposition in JBL7 (this study) and SIB06, a core from West Siberian Lowland, Russia (data from Philben et al . []). The plant community was calculated in both cores as the mean of results from the neutral sugar and lignin phenol methods (section 2.3).…”

“…This index was converted to a quantitative estimate of the Sphagnum contribution to total peat carbon using the equation: where SI Carb is the carbohydrate Sphagnum index and f Sphagnum is the fractional contribution of Sphagnum to the peat carbon [ Philben et al ., ]. The vascular plant contribution was calculated by difference.…”

“…Lignin phenols were used as an independent estimate of the paleovegetation according to the equation: where f Vascular is the fraction of carbon from vascular plants, VPI Phenol is the phenol vascular plant index (nmol V + S phenols mg C −1 ), and 220 nmol mg C −1 is the average VPI Phenol in fresh vascular plants [ Philben et al ., ]. The Sphagnum contribution was calculated by difference.…”