Plant foliar nutrient response to active layer and water table depth in warming permafrost soils

Abstract

1. Thawing permafrost in northern latitudes has led to deepening active soil layers and fluctuating water tables. This could increase plant access to permafrostderived nitrogen (N), phosphorus (P) and other nutrients such as calcium (Ca) and magnesium (Mg), and subsequently increase plant productivity and ecosystem carbon storage and nutrient cycling. We hypothesized that deepening permafrost thaw and water table fluctuations would alter species-specific foliar N:P ratios. Since there is often more P, Ca and Mg available in the deeper mineral soil layers and more N available in the shallow organic layers, we expected that deeply rooted species would decrease foliar N:P ratios due to root proximity to thawing mineral soil, and plants with shallower rooting systems mostly in the organic layer would increase foliar N:P ratios.2. We assessed foliar and canopy nutrient responses of seven vascular plant species in moist acidic tussock tundra vegetation in the northern foothills of the Alaska Range to variable soil thaw depths and water table levels induced by either a natural thermokarst gradient or a winter warming snow fence experiment.3. In both the natural thermokarst gradient and the warming experiment, wet or deeply thawed areas generally led to an increase in foliar nutrient concentrations and greater canopy mass and canopy nutrients. For the majority of species, foliar N:P ratios remained proportional or decreased in deciduous species in wet sites, with the exception of one shallowly rooted species that increased foliar N:P ratio in deeply thawed sites. Overall, plant acquisition of P was more related to water table level than to thaw depth, and water table modulated the canopy biomass response of the species at the warming experiment. 4. Synthesis. Foliar N:P ratios suggest that plant species in this tussock tundra ecosystem are either remaining or becoming more N-limited as thaw depth deepens and water table level rises, indicating that P is not likely to become the primary limiting nutrient with the progression of permafrost thaw. However, the amount of deeply thawed, wet areas that develop on the landscape as permafrost thaws will be important contributors in the total movement of nutrients above-ground.

Changing sub-Arctic tundra vegetation upon permafrost degradation: impact on foliar mineral element cycling

“…The sampling was performed between mid-August and early September 2019 (i.e., at the late-season period). For both sites, leaf samples were dried at 60 • C and ground (Jasinski et al, 2022;Natali et al, 2011;Schuur et al, 2007).…”

“…Since the beginning of the monitoring (in 1990), the Minimal thaw area showed less ground subsidence and little-disturbed moist acidic tundra and is dominated by the sedge E. vaginatum and Sphagnum spp. mosses, coexisting with evergreen and deciduous shrubs (Jasinski et al, 2022;Schuur et al, 2007). The Moderate thaw area displays isolated areas of ground subsidence (Schuur et al, 2007) and remains dominated by the sedge E. vaginatum, with a lower moss cover than the Minimal thaw area (Jasinski et al, 2018).…”

Short-term effects of hurricanes on nitrate-nitrogen runoff loading: a case study of Hurricane Ida using E3SM land model (v2.1)

“…Because groundwater depths can significantly influence soil nutrient concentrations in various ecosystems (Hefting et al, 2004;Miao et al, 2013;Jasinski et al, 2022;Zhang et al, 2022), we first calibrated ELM based on the groundwater table depth (WTD) simulated by ELM-170 ParFlow (Fang et al, 2022;Tran et al, 2024) in which lateral hydrological flow was simulated…”

Soil microenvironmental variation drives below‐ground trait variation and interacts with macroclimate to structure above‐ground trait variation of arctic shrubs

“…Recent investigations support this, indicating that intraspecific trait variation of several tundra plant species is strongly related to microclimate, including local temperature, soil moisture content and snow conditions (Kemppinen et al., 2021; Kemppinen & Niittynen, 2022). Studies have also found that changes in local thaw depth can lead to variation in plant chemistry by altering nutrient availability and plant uptake (Blume‐Werry et al., 2019; Jasinski et al., 2022). At the same time, broad‐scale studies show consistent relationships between intraspecific trait variation and macroclimate across the tundra biome (Bjorkman et al., 2018; Kudo et al., 2001).…”