Soil formation and weathering in a permafrost environment of the Swiss Alps: a multi‐parameter and non‐steady‐state approach

Abstract

Spatially discontinuous permafrost conditions frequently occur in the European Alps. How soils under such conditions have evolved and how they may react to climate warming is largely unknown. This study focuses on the comparison of nearby soils that are characterised by the presence or absence of permafrost (active‐layer thickness: 2–3 m) in the alpine (tundra) and subalpine (forest) range of the Eastern Swiss Alps using a multi‐method (geochemical and mineralogical) approach. Moreover, a new non‐steady‐state concept was applied to determine rates of chemical weathering, soil erosion, soil formation, soil denudation, and soil production. Long‐term chemical weathering rates, soil formation and erosion rates were assessed by using immobile elements, fine‐earth stocks and meteoric 10Be. In addition, the weathering index (K + Ca)/Ti, the amount of Fe‐ and Al‐oxyhydroxides and clay minerals characteristics were considered. All methods indicated that the differences between permafrost‐affected and non‐permafrost‐affected soils were small. Furthermore, the soils did not uniformly differ in their weathering behaviour. A tendency towards less intense weathering in soils that were affected by permafrost was noted: at most sites, weathering rates, the proportion of oxyhydroxides and the weathering stage of clay minerals were lower in permafrost soils. In part, erosion rates were higher at the permafrost sites and accounted for 79–97% of the denudation rates. In general, soil formation rates (8.8–86.7 t/km2/yr) were in the expected range for Alpine soils. Independent of permafrost conditions, it seems that the local microenvironment (particularly vegetation and subsequently soil organic matter) has strongly influenced denudation rates. As the climate has varied since the beginning of soil evolution, the conditions for soil formation and weathering were not stable over time. Soil evolution in high Alpine settings is complex owing to, among others, spatio‐temporal variations of permafrost conditions and thus climate. This makes predictions of future behaviour very difficult. Copyright © 2016 John Wiley & Sons, Ltd.

Tracing the temporal evolution of soil redistribution rates in an agricultural landscape using 239+240Pu and 10Be

“…Lal, 2001;Balco et al, 2008). The approaches of Lal (2001) and Zollinger et al (2017) achieve quite similar results. Due to pedogenic processes or human impact, the distribution pattern along the profile may be disturbed and, particularly in relatively young soils, far from a state of equilibrium.…”

“…Soil erosion rates calculated using meteoric and in situ 10 Be were moderately comparable when employing the approach according to Hidy et al (2010) or that of Zollinger et al (2017). Considering only the buried soil, the erosion rates were slightly higher compared to the rates of the whole VAMOS profile using the approaches of Lal (2001), Zollinger et al (2017) and also MODERN. At the site LP12N, relatively high long-term erosion rates of 1.6 t ha -1 yr -1 (Hidy et al, 2010) to 2.1 t ha -1 yr -1 (Zollinger et al, 2017) were measured whereas the foot-slope site (or lower slope position) exhibited smaller erosion rates when considering the whole soil profile VAMOS; however, this profile however has a buried soil.…”

“…Due to the fact that LP4 is considered as the reference site, soil redistribution rates are assumed to be zero for the short-term rates. At the site LP12N, relatively high long-term erosion rates of 1.6 t ha -1 yr -1 (Hidy et al, 2010) to 2.1 t ha -1 yr -1 (Zollinger et al, 2017) were measured whereas the foot-slope site (or lower slope position) exhibited smaller erosion rates when considering the whole soil profile VAMOS; however, this profile however has a buried soil. Soil erosion rates calculated using meteoric and in situ 10 Be were moderately comparable when employing the approach according to Hidy et al (2010) or that of Zollinger et al (2017).…”

“…As reported in Egli et al (2010), the 10 Be deposition rates are mostly unknown for a specific area and have to be estimated. With soil erosion, Equation (1) is extended to the following non-steady-state approach (Zollinger et al, 2017): With soil erosion, Equation (1) is extended to the following non-steady-state approach (Zollinger et al, 2017):…”

“…Another problem is that often steady-state conditions are assumed to calculate denudation or soil production rates; an assumption that may lead to unrealistic representations of the dynamics of pedogenesis and weathering profile evolution (Phillips, 2010) if the requirements for a steadystate are not fulfilled. With known surface ages, denudation rates can also be calculated using meteoric 10 Be (Zollinger et al, 2017) even under a non-steady-state situation. Schaller et al, 2010;Hidy et al, 2010).…”