Diatom-based water-table reconstruction in Sphagnum peatlands of northeastern China

Abstract

Peatlands are important ecosystems for biodiversity conservation, global carbon cycling and water storage. Hydrological changes due to climate variability have accelerated the degradation of global and regional ecosystem services of peatlands.Diatoms are important producers and bioindicators in wetlands, but comprehensive diatom-based inference models for palaeoenvironmental reconstruction in peatlands are scarce. To explore the use of diatoms for investigating peatland hydrological change, this study established a training set consisting of diatom composition and twelve environmental factors from 105 surface samples collected from five Sphagnum peatlands in northeastern China. Diatom communities were dominated by Eunotia species. Ordination analyses showed that depth to the water table (DWT) was the most important factor influencing diatom distribution, independently accounting for 4.99% of total variance in diatom data. Accordingly, a diatom-based DWT transfer function was developed and thoroughly tested. The results revealed that the best-performing model was based on weighted averaging with inverse deshrinking (R 2 = 0.66, RMSEP = 8.8 cm with leave-one-out cross validation). Quantitative reconstruction of DWT on a short peat core collected from the Aershan Peatland (Inner Mongolia) recorded climate-mediated hydrological changes over the last two centuries. This study presents the first diatom-water table transfer function in Sphagnum peatlands, and highlights the potential of diatoms as a powerful tool to assess the magnitude of past hydrological changes in peatlands of northeastern China, as well as similar peat environments worldwide.

Effects of climate change on a subtropical montane peatland over the last two centuries: Evidence from diatom records

“…Most of the 197 species identified in surface samples have been previously observed in peatlands (Buczkó and Wojtal, 2005; Chen et al, 2020; Mutinová et al, 2017; Poulíčková et al, 2004). Diatom communities were closely associated with physical (i.e.…”

“…Besides temperature, precipitation was one potential driving force for changes in diatom communities. In SHH core, the wet period between AD 1750 and 1780 was characterized by taxa preferring wet and acid-neutral habitats, including Caloneis species and Pinnularia gibba Ehrenberg (Chen et al, 2020; Hargan et al, 2015; Ma et al, 2018). Continuous and plentiful rainfall during the wet period (AD 1750–1780) would raise the water table (Figure 9), subsequently decreasing organic matter decomposition rates by creating anoxic conditions (Ise et al, 2008).…”

“…Therefore, the peak activity of 137 Cs could not be used to identify the 1963 fallout maximum that arose from the atmospheric testing of high-yield thermonuclear weapons (Appleby, 2001). 210 Pb total reached a radioactive equilibrium value that was higher than 226 Ra (Figure 5), probably due to the level of efficiency calibration error of the gamma spectrometer (Chen et al, 2020). Supported 210 Pb activity was calculated from the mean activity in the bottom layers (i.e.…”

“…Diatoms, one group of ubiquitous and diverse algae, are known to be ecosystem engineers in wetlands, since they have high productivity, regulate nutrient cycling and form the basis for complex food webs (Gaiser and Rühland, 2010; Kokfelt et al, 2009). Although diatom communities are less frequently investigated in peatlands than other types of wetlands, increasing evidence has demonstrated that diatoms are barometers of peatland environmental changes (Carballeira and Pontevedra-Pombal, 2020; Gaiser and Rühland, 2010), such as anthropogenic disturbances (Poulíčková et al, 2013) and hydrosere succession (Brugam and Swain, 2000; Chen et al, 2020; Fukumotoet al, 2014; Hargan et al, 2015; Li et al, 2020; Ma et al, 2018; Rühland et al, 2006). For example, dominant diatom species shifted from Pinnularia to Eunotia species in a boreal peatland of Northern Sweden, indicating the succession from a bog to a sedge peatland (Kokfelt et al, 2009).…”

“…Paleoclimate data from eastern China have demonstrated a rising temperature trend since the early 20th century, concurrent with high rainfall variability (Liu et al, 2005). It can be expected that climate warming will enhance peat decomposition and increase nutrient availability (Bragazza et al, 2013; Laiho, 2006), while rainfall variability can alter moisture conditions (Chen et al, 2020; Li et al, 2020). In these subtropical montane peatlands, diverse diatom species have been found in surface samples (Chen et al, 2017).…”