More Like this

1. Decoupling of redox processes from soil saturation in Arctic tundra

   https://doi.org/10.1038/s43247-024-01927-1  

   Rooney, Erin_C; VanderJeugdt, Erin; Avasarala, Sumant; Miah, Imtiaz; Berens, Matthew_J; Kinsman-Costello, Lauren; Weintraub, Michael_N; Herndon, Elizabeth_M (November 2024, Communications Earth & Environment)
2. Soil resources vs. physicochemical soil properties as drivers of abundance and diversity of low Arctic soil mesofauna communities

   https://doi.org/10.1007/s00300-024-03254-9  

   Klein, R R; Ball, B A (June 2024, Polar Biology)

   Soil mesofauna play pertinent roles in soil processes. For example, microarthropods strongly influence rates of microbial decomposition. The relationship between mesofauna and their environment are understudied in low Arctic ecosystems compared to other regions. A more detailed grasp of these soil assemblages is necessary for understanding the current functioning of these ecosystems. We characterized the soil mesofauna community across different low Arctic habitats to determine which soil properties commonly correlated with soil fauna would best explain their distribution, abundance, and diversity. Samples were taken near five different lakes in northern Finland, in both alpine meadows and sub-alpine birch forests, across a span of available soil habitats (measured by pH, salinity, organic and nitrogen content, soil moisture). Total abundance of the mesofauna community was influenced by a combination of soil factors, but most individual taxa, as well as measures of diversity were best explained by models of one or two influential soil parameters. Poduromorpha springtails and Oribatid mites were best modeled by measures of resource availability, although only Oribatids were significantly, positively related to these resources. All mites and Entomobryomorphid springtails were positively influenced by physicochemical soil moisture and/or salinity. Salinity, in particular, had a strong influence on overall mesofauna community composition. Our results provide further insight into soil fauna assemblages in Northern Finland and further, more extensive research would contribute to a more comprehensive foundation. This will allow for better monitoring of community changes and responses in the face of climate change in the low Arctic. 

   more » « less
3. Methane production in laboratory incubations of Arctic soil at three temperatures, 2018

   https://doi.org/10.18739/A2M32NB59  

   Lipson, David (January 2021, NSF Arctic Data Center)

   When wet Arctic tundra soils begin to freeze in the fall, an unfrozen layer remains between the frozen surface and deeper permafrost layers. This period is known as the zero curtain, as liquid water keeps the temperature of this soil layer near 0 Celsius (C) while latent heat is gradually dissipated. This experiment compares the temperature response of the methanogenic community in the zero curtain period with that of the summer community to test whether the zero curtain methanogenic community is especially cold adapted. This dataset includes methane production rates measured in anaerobic laboratory incubations of soils collected from two dates (July and Nov 2018) at temperatures around 0, 4 and 10C. 

   more » « less
4. Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems

   https://doi.org/10.1029/2019JG005242  

   Arndt, Kyle A.; Oechel, Walter C.; Goodrich, Jordan P.; Bailey, Barbara A.; Kalhori, Aram; Hashemi, Josh; Sweeney, Colm; Zona, Donatella (August 2019, Journal of Geophysical Research: Biogeosciences)

   Abstract The atmospheric methane (CH₄) concentration, a potent greenhouse gas, is on the rise once again, making it critical to understand the controls on CH₄emissions. In Arctic tundra ecosystems, a substantial part of the CH₄budget originates from the cold season, particularly during the “zero curtain” (ZC), when soil remains unfrozen around 0 °C. Due to the sparse data available at this time, the controls on cold season CH₄emissions are poorly understood. This study investigates the relationship between the fall ZC and CH₄emissions using long‐term soil temperature measurements and CH₄fluxes from four eddy covariance (EC) towers in northern Alaska. To identify the large‐scale implication of the EC results, we investigated the temporal change of terrestrial CH₄enhancements from the National Oceanic and Atmospheric Administration monitoring station in Utqiaġvik, AK, from 2001 to 2017 and their association with the ZC. We found that the ZC is extending later into winter (2.6 ± 0.5 days/year from 2001 to 2017) and that terrestrial fall CH₄enhancements are correlated with later soil freezing (0.79 ± 0.18‐ppb CH₄day⁻¹unfrozen soil). ZC conditions were associated with consistently higher CH₄fluxes than after soil freezing across all EC towers during the measuring period (2013–2017). Unfrozen soil persisted after air temperature was well below 0 °C suggesting that air temperature has poor predictive power on CH₄fluxes relative to soil temperature. These results imply that later soil freezing can increase CH₄loss and that soil temperature should be used to model CH₄emissions during the fall. 

   more » « less
5. Soil enzymes illustrate the effects of alder nitrogen fixation on soil carbon processes in arctic and boreal ecosystems

   https://doi.org/10.1002/ecs2.3818  

   Heslop, Calvin B.; Ruess, Roger W.; Kielland, Knut; Bret‐Harte, M. Syndonia (November 2021, Ecosphere)

   Abstract As tall shrubs increase in extent and abundance in response to a changing climate, they have the potential to substantially alter Arctic and boreal ecosystem nutrient cycling and carbon (C) balance. Siberian alder (Alnus viridisssp.fruticosa), a nitrogen (N) fixing shrub, is among the species responding to climate warming in both the Arctic and boreal forests. By relieving N limitation of microbial activity, alder‐fixed N has the potential to increase decomposition of labile soil C. Simultaneously, it may also decrease decomposition of recalcitrant soil C by downregulating microbial N mining. The microbial response to N additions is influenced by differences in the soil organic matter (SOM) chemistry and could ultimately determine whether alder N additions result in a net sink or source of C to the atmosphere. We measured the activities of three extracellular enzymes in bulk organic soils under and away from alder canopies in stands differing in SOM chemistry in both the arctic and boreal forest regions of Alaska, USA. In the Arctic, samples taken from under alder had higher activities of both recalcitrant and labile C‐degrading enzymes than samples taken away, regardless of SOM chemistry. In the boreal forest, enzyme activities did not differ with alder proximity nor stand SOM chemistry, possibly due to long legacies of alder N inputs in these stands. As arctic and boreal forest ecosystems experience shifts in the distribution and abundance of this N‐fixing shrub, alders' influence on soil decomposition could have significant consequences for high latitude soil C budgets. 

   more » « less