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BNZ-LTER Metadata Catalog
| Title: | Eight Mile Lake Research Watershed, Thaw Gradient: Seasonal water table depth from 2004-2024 |
| Contacts: |
Celis, Gerardo Ledman, Justin McGroarty, Megan Rodenhizer, Heidi G Schaedel, Christina Schuur, Edward |
| Abstract: | In this larger study, we are asking the question: Is old carbon that comprises the bulk of the soil organic matter pool released in response to thawing of permafrost? We are answering this question by using a combination of field and laboratory experiments to measure radiocarbon isotope ratios in soil organic matter, soil respiration, and dissolved organic carbon, in tundra ecosystems. The objective of these proposed measurements is to develop a mechanistic understanding of the SOM sources contributing to C losses following permafrost thawing. We are making these measurements at an established tundra field site near Healy, Alaska in the foothills of the Alaska Range. Field measurements center on a natural experiment where permafrost has been observed to warm and thaw over the past several decades. This area represents a gradient of sites each with a different degree of change due to permafrost thawing. As such, this area is unique for addressing questions at the time and spatial scales relevant for change in arctic ecosystems. |
| Methods: | Water table depth in relation to the soil surface was measured once every two weeks throughout the snow-free period in water wells. Water table depth data are presented during the time period when wells were ice-free (~ mid-June through September). Water table depth in relation to the soil surface was measured once every week in 2023 throughout the snow-free period in water wells. Water table depth data are presented during the time period when wells were ice-free (~ mid-June through September). Water table depth in relation to the soil surface was measured once every week in 2024 throughout the snow-free period in water wells. Water table depth data are presented during the time period when wells were ice-free (~ mid-June through September). |
| Experimental Design: | The study site at the Eight Mile Lake watershed is located in the northern foothills of the Alaska Range. Permafrost temperature has been monitored annually on a gentle north-facing slope at this site, in a 30 m deep borehole that was installed in 1985 before the permafrost started to thaw. While permafrost thaw can sometimes result in water ponding depending on local topography, this landscape consists largely of relatively well-drained uplands. In this watershed, we monitored three sites that represented differing amounts of change as a result of permafrost thaw based on observations of ground subsidence and depth of thaw. Our minimal thaw site had the shallowest summer thaw depth and the least ground surface subsidence, and the vegetation was typical moist acidic tundra, dominated by the tussock-forming sedge, Eriophorum vaginatum, with coexisting deciduous and evergreen shrubs, and an understory of mosses and lichens. A second site, located adjacent to the borehole, had moderate summer thaw depths and increased ground subsidence. Here the vegetation composition was similar to our minimal thaw site, but with increased biomass of all plant groups. Lastly, an extensive thaw site was located in an area where permafrost degradation had occurred at least several decades prior to the establishment of the borehole; thermokarst can already be observed in air photos of the area taken in 1954. This site had the deepest summer thaw depth and the most ground subsidence, and the plant biomass has shifted to dominance by shrubs, including blueberry (Vaccinium uliginosum) and cloudberry (Rubus chamaemorus), at the expense of sedges. |
| Supplemental Documentation: | None on file. |
| Corrections: | Data processing: data were checked for outliers and missing values which were replaced with NA. Data are provided for the ice-free period (~mid-June through September); early in the season some wels contain ice after most others have thawed, these are also marked 'NA'. |
| Supplemental Acknowledgements: | The Schuur lab data provided on this site are freely available and were furnished by individual Schuur lab members who encourage their use. Please kindly email the appropriate Schuur lab scientist(s) (PI) to inform them of how you intend to use the data and of any publication plans. It is also important to contact the Schuur lab investigator to assure you are downloading the latest revision of the data and to prevent potential misuse or misinterpretation of the data. Please acknowledge the data source as a citation. If the Schuur lab (PIs) feel that they should be acknowledged or offered participation as authors, they will let you know and we assume that an agreement on such matters will be reached before publishing and/or use of the data for publication. If your work directly competes with the Schuur lab analysis they may ask that they have the opportunity to submit a manuscript before you submit one that uses unpublished data. In addition, when publishing please acknowledge the agency that supported the research. Lastly, we kindly request that those publishing papers using Schuur lab data provide reprints to the PIs. [This statement taken from The Ameriflux Network data sharing policy]. Funding Acknowledgements: This work was based in part on support provided by the following programs: U.S. Department of Energy, Office of Biological and Environmental Research, Terrestrial Ecosystem Science (TES) Program, Award #DE-SC0006982 and updated with DE-SC0014085 (2015-2018) and DE-SC0020227 (2019-2022); National Science Foundation CAREER program, Award #0747195; National Parks Inventory and Monitoring Program; National Science Foundation Bonanza Creek LTER program, Award #1026415; National Science Foundation Office of Polar Programs, Award #1203777”; NNA: LTREB: The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation (Award # 1754839). |
| Keywords: | permafrost, snowfences, thaw, thermokarst, tundra, warming, water table |
| Categories: | Biogeochemistry, Climate, Decomposition, Disturbance, Primary Production, Vegetation |
| Study Period: | 2004-06-19 to 2024-09-29 |
| Sampling Frequency: | during snow-free period, every other week |
| Bounding Box: |
West Longitude: -149.2535833° |
| Site References: |
Site ID: EML |
| Data Columns: |
Column: 1 Column: 2 Column: 3 Column: 4 Column: 5 |
| Public Release: | 2025-02-10 |
