Saturated Hydraulic Conductivity in Northern Peats Inferred From Other Measurements

Abstract

Introduction Background and RationalePeatlands are organic-rich wetlands that provide important ecosystem services at a range of spatial scales (Kimmel & Mander, 2010). Local hydrological setting is of central importance in determining the characteristics and functions of these ecosystems (Siegel & Glaser, 2006). Peatlands are characterized by waterlogged, anoxic conditions that suppress microbial decomposition, causing carbon to accumulate slowly but persistently over thousands of years in the form of partially decomposed plant detritus (Yu et al., 2010). Peatlands cover less than 3% of the Earth's land surface (Xu et al., 2018b) yet they are thought to store between approximately 500 and 600 Gt (5-6 × 10 17 g) of carbon (Müller & Joos, 2020;Page et al., 2011;Yu, 2011Yu, , 2012, equivalent to between approximately one sixth and one third of global soil carbon (Scharlemann et al., 2014). As well as being long-term carbon sinks, peatlands also emit greenhouse gases, particularly carbon dioxide (CO 2 ) and methane. Peatland greenhouse gas budgets are highly sensitive to surface wetness, and even modest changes in water-table depths can cause peatlands to switch between being net sinks and sources of greenhouse gases when measured in CO 2 -equivalent units (Evans et al., 2021;Günther et al., 2020). In some locations, water that drains from peat

Controls on Saturated Hydraulic Conductivity in a Degrading Permafrost Peatland Complex

“…The peat K sat model by Morris et al (2022) accounted for a lower proportion of the variance in log 10 (K h ) at Rensjön palsa mire (r 2 = 0.528; 𝐴𝐴 𝐴𝐴 2 𝑎𝑎𝑎𝑎𝑎𝑎 = 0.429) than our site-specific LMM (see Section 3.1, above). Setting the trophic type of the site to be unspecified resulted in model predictions that had substantial bias (ρ c = 0.604) and consistently underestimated measured log 10 (K h ), particularly for shallow peats with high log 10 (K h ) (Figure 4b).…”

“…We evaluated the ability of an existing pedotransfer function for peat K sat by Morris et al (2022), trained primarily on boreal and temperate peats, to predict our measurements of log 10 (K h ) at Rensjön palsa mire. We tested the best-performing model from Morris et al (2022), which they termed Model 1, and which requires the continuous predictors log 10 (depth), log 10 (DBD), and von Post score (all measured in this study), and the categorical predictors trophic type (e.g., bog, fen), microform (e.g., hummock, hollow), and the Kerner Oceanity Index (KOI) (Morris et al, 2022). We initially classified the trophic type and microform of our samples as the unspecified category given by Morris et al (2022), because palsa mires were not represented in the training data used to fit their model.…”

“…Measured values of peat K h for Rensjön palsa mire varied from 4.85 × 10 −7 to 3.61 × 10 −4 m s −1 . Palsa peats had a broad range of humification (H1 to H8), and had a higher average DBD (median = 0.14 g cm −3 ; range = 0.05-0.31 g cm −3 ) than the boreal and temperate peats used to train the multi-site model of peat K sat by Morris et al (2022) (median = 0.09 g cm −3 ; range = 0.01-0.30 g cm −3 ). Inspection of simple bivariate plots indicates that log 10 (K h ) is negatively related to log 10 (depth), log 10 (DBD) and von Post score (Figures 3a-3c).…”

Underground mining magnifies drought impacts in an adjacent protected raised bog

“…Mires in the Tomsk region (Dyukarev & Pologova, 2011; Kopysov et al, 2020) with thicker peat deposits have been reported to be more resistant to the vertical drainage. The hydraulic conductivity can vary by several orders of magnitude, even for the same peat type (Morris et al, 2022; Paat et al, 2022). Direct measurements and indirect estimates show that the lowest conductivity values in raised bogs of northeastern Estonia occur near the bottom of the peat column in highly decomposed ( von Post score H7‐H10) peats formed at the fen and transitional mire growth stages.…”

The dependence of evaporative efficiency of vegetated surfaces on ground cover mass fractions in vegetated soils in mesic ecosystems

“…As for now, a texture‐based pedotransfer function is used for mineral soils (Lehmann et al, 2018; Merlin et al, 2016) that has proven to work well for bare soils across the world, but for peat, it is still in progress (Chapman et al, 2017; Van Looy et al, 2017). A recent meta‐analysis on 2507 northern peat samples provided several empirical equations for predicting saturated hydraulic conductivity using site information (Morris et al, 2022), which may serve as the basis for developing a similar texture‐based pedotransfer function for peats.…”