Arctic vegetation change driven by water tables and soil nitrogen in a thawing permafrost tundra

Kadej, Stephanie (2023) Arctic vegetation change driven by water tables and soil nitrogen in a thawing permafrost tundra. Masters thesis, Northern Arizona University.

Text Kadej_2023_arctic_vegetation_change_driven_by_water_tables_soil_nitrog.pdf - Published Version Download (1MB)

Abstract

High-latitude ecosystems are experiencing rapid change due to climate warming, with temperatures rising up to 4 times faster than the global average. The magnitude of carbon(C) stored in these perennially frozen soils, known as permafrost, is nearly 3 times that of the atmosphere with the potential for release as warming leaves these soils vulnerable to thaw and microbial decomposition. Arctic vegetation has the potential to offset C release from permafrost soils because deepening of the active layer releases previously unavailable nutrients for plant uptake. This study investigated changes in productivity and species composition in the Carbon in Permafrost Experimental Heating Research project (CiPEHR) located in moist acidic tundra underlain by permafrost. Direct biomass measurements collected in 2022 were compared across Air and/or Soil warming treatments and plant functional types. Measurements of plant community composition, collected between 2009-2021, using the point-intercept method, were used to analyze changes in species composition over time. Changes in biomass were related to environmental variables such as water table and active layer depth, etc. collected over the course of the experiment. After 14 years, plot trajectories diverged and created environmental gradients. Soil warming led to higher overall species composition change over time, resulting in higher deciduous shrub biomass, while reducing graminoid and non-vascular species biomass. These changes were largely driven by increasing water tables, thaw depths, and the interaction of water tables and soil nitrogen availability. This suggests heterogeneity in soil moisture and soil nitrogen as an increasingly important drivers of vegetation change.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Arctic; biogeochemistry; carbon cycling; community composition; permafrost; vegetation
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited:	23 Jul 2026 21:53
Last Modified:	23 Jul 2026 21:53
URI:	https://openknowledge.nau.edu/id/eprint/6300

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