Journal
GEODERMA
Volume 421, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.geoderma.2022.115915
Keywords
sub-Arctic tundra; permafrost degradation; shrubification; topsoil; mineral elements; vegetation change
Categories
Funding
- European Research Council (ERC) under the European Union [714617]
- Fonds National de la Recherche Scientifique (FNRS, Belgium) [FC69480]
- National Science Foundation Long Term Research in Environmental Biology (LTREB Award) [1754839]
- Department of Energy NICCR Program
- Department of Energy Terrestrial Ecosystem Processes
- National Science Foundation CAREER Program
- National Parks Inventory and Monitoring Program
- National Science Foundation Bonanza Creek LTER program
- National Science Foundation Office of Polar Programs
- Arctic Natural Sciences Program
- Division Of Environmental Biology
- Direct For Biological Sciences [1754839] Funding Source: National Science Foundation
- European Research Council (ERC) [714617] Funding Source: European Research Council (ERC)
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Climate change affects the Arctic and sub-Arctic regions by thawing previously frozen permafrost, which has implications for plant growth and soil composition. This study investigated the changes in vegetation and soil mineral element composition during permafrost degradation and found differences between plant species. Increased shrubification resulted in decreased concentrations of certain elements in the soil, while other elements remained relatively stable.
Climate change affects the Arctic and sub-Arctic regions by exposing previously frozen permafrost to thaw, unlocking soil nutrients, changing hydrological processes, and boosting plant growth. As a result, sub-Arctic tundra is subject to a shrub expansion, called shrubification, at the expense of sedge species. Depending on the intrinsic foliar properties of these plant species, changes in foliar mineral element fluxes with shrubification in the context of permafrost degradation may influence topsoil mineral element composition. Despite the potential implications of changes in topsoil mineral element concentrations for the fate of organic carbon, this remains poorly quantified. Here, we investigate vegetation foliar and topsoil mineral element composition (Si, K, Ca, P, Mn, Zn, Cu, Mo, V) across a natural gradient of permafrost degradation at a typical sub-Arctic tundra at Eight Mile Lake (Alaska, USA). Results show that foliar mineral element concentrations are higher (up to 9 times; Si, K, Mo for all species, and for some species Zn) or lower (up to 2 times; Ca, P, Mn, Cu, V for all species, and for some species Zn) in sedge than in shrub species. As a result, a vegetation shift over similar to 40 years has resulted in lower topsoil concentrations in Si, K, Zn, and Mo (respectively of 52, 24, 20, and 51%) in highly degraded permafrost sites compared to poorly degraded permafrost sites due to lower foliar fluxes of these elements. For other elements (Ca, P, Mn, Cu, and V), the vegetation shift has not induced a marked change in topsoil concentrations at this current stage of permafrost degradation. A modeled amplified shrubification associated with a further permafrost degradation is expected to increase foliar Ca, P, Mn, Cu, and V fluxes, which will likely change these element concentrations in topsoil. These data can serve as a first estimate to assess the influence of other shifts in vegetation in Arctic and sub-Arctic tundra such as sedge expansion under wetter soil conditions.
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