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This data set is part of NSF OPP – 2109946 Collaborative Research: Plant phenology, local adaptation, and growing season length in the changing Arctic tundra. ddRAD sequencing was performed on populations of Salix pulchra and Carex bigelowii across a latitudinal gradient in north central Alaska from East of Fairbanks to the North Coast near Prudhoe Bay for comparative population genomics analysis. This study was intended to better understand historical biogeography of major elements of the plant community to determine if: (1) there is comparable evidence of historical gene flow among all these taxa along the same latitudinal gradient in north central Alaska: and (2) there is evidence of genetic structure linked to adaptation for latitude or specific site of origin across lineages. 

This data set is part of NSF OPP – 2109946 Collaborative Research: Plant phenology, local adaptation, and growing season length in the changing Arctic tundra. The data includes RNAseq fasta and gene ID files for Eriophorum vaginatum originating from growth chamber experiments and field experiments for ecotypes originating from Taiga ecosystem, Coldfoot Camp (67.2631, -150.1591) or Tundra ecosystem, Sagwon (69.4244, -148.6976). Growth chambers were from 4 time points from pre-senescence to complete senescence of leaves through 4 different experimental settings including (1) constant temperature and light matching peak growing season, (2) Natural light and temperature of Sagwon through a growing season, (3) constant peak season light + natural field season temperature, (4) constant peak season temperature + natural field season light. Field data are from plants transplanted to Sagwon from Coldfoot and Sagwon with data collected weekly after plants reach the beginning of senescence. Data originates from RNA (Ribonucleic Acid) extraction collected from whole tiller leaf material followed by RNA sequencing. This study was designed to understand the genetic mechanisms underlying ecotype specific timing of senescence in relation to light and temperature. 

See also the Commentary on this article by Wilcox, 239 : 452–455 . 

Abstract The response of plant leaf and root phenology and biomass in the Arctic to global change remains unclear due to the lack of synchronous measurements of above- and belowground parts. Our objective was to determine the phenological dynamics of the above- and belowground parts of Eriophorum vaginatum in the Arctic and its response to warming. We established a common garden located at Toolik Lake Field Station; tussocks of E. vaginatum from three locations, Coldfoot, Toolik Lake and Sagwon, were transplanted into the common garden. Control and warming treatments for E. vaginatum were set up at the Toolik Lake during the growing seasons of 2016 and 2017. Digital cameras, a handheld sensor and minirhizotrons were used to simultaneously observe leaf greenness, normalized difference vegetation index and root length dynamics, respectively. Leaf and root growth rates of E. vaginatum were asynchronous such that the timing of maximal leaf growth (mid-July) was about 28 days earlier than that of root growth. Warming of air temperature by 1 °C delayed the timing of leaf senescence and thus prolonged the growing season, but the temperature increase had no significant effect on root phenology. The seasonal dynamics of leaf biomass were affected by air temperature, whereas root biomass was correlated with soil thaw depth. Therefore, we suggest that leaf and root components should be considered comprehensively when using carbon and nutrient cycle models, as above- and belowground productivity and functional traits may have a different response to climate warming. 

Global climate change has resulted in geographic range shifts of flora and fauna at a global scale. Extreme environments, like the Arctic, are seeing some of the most pronounced changes. This region covers 14% of the Earth’s land area, and while many arctic species are widespread, understanding ecotypic variation at the genomic level will be important for elucidating how range shifts will affect ecological processes. Tussock cottongrass ( Eriophorum vaginatum L.) is a foundation species of the moist acidic tundra, whose potential decline due to competition from shrubs may affect ecosystem stability in the Arctic. We used double-digest Restriction Site-Associated DNA sequencing to identify genomic variation in 273 individuals of E. vaginatum from 17 sites along a latitudinal gradient in north central Alaska. These sites have been part of 30 + years of ecological research and are inclusive of a region that was part of the Beringian refugium. The data analyses included genomic population structure, demographic models, and genotype by environment association. Genome-wide SNP investigation revealed environmentally associated variation and population structure across the sampled range of E. vaginatum , including a genetic break between populations north and south of treeline. This structure is likely the result of subrefugial isolation, contemporary isolation by resistance, and adaptation. Forty-five candidate loci were identified with genotype-environment association (GEA) analyses, with most identified genes related to abiotic stress. Our results support a hypothesis of limited gene flow based on spatial and environmental factors for E. vaginatum , which in combination with life history traits could limit range expansion of southern ecotypes northward as the tundra warms. This has implications for lower competitive attributes of northern plants of this foundation species likely resulting in changes in ecosystem productivity. 

This data set is associated with Curasi et al., 2022 (https://doi.org/10.1088/1748-9326/ac6005) it includes detailed survey data for Eriophorum vaginatum spanning sites in the Alaskan, Canadian, and Russian Arctic. The data set includes detailed surveys of tussock density and diameter, shrub basal diameter and abundance, the relationship between tussock size and mass, the relationship between shrub size and mass, tussock chemical properties, soil properties, and bulk density. It also includes outputs and projections from a tussock machine learning ecological niche model. This data was collected to characterize the distribution of this foundation species across the landscape and illustrate its role in the ecosystem. The data collection methods and subsequent analysis are described in detail in https://doi.org/10.1088/1748-9326/ac6005 

Leaf toughness is an important functional trait that confers resistance to herbivory and mechanical damage. We sought to determine how species composition, climate, seasonality, and nutrient availability influence leaf toughness in two types of tundra in northern Alaska. We measured leaf toughness as force to punch for 11 species of Arctic plants in tussock tundra and dry heath tundra at 17 sites distributed along a latitudinal gradient. Rubus chamaemorus L. and the graminoids occupied opposite ends of the leaf toughness spectrum, with Rubus chamaemorus requiring the least force to punch, whereas one of the graminoids, Eriophorum vaginatum L., required the most. Leaf toughness increased with mean summer temperature for Eriophorum vaginatum and Betula nana L., whereas it declined with warmer temperatures for the other species. Toughness of mature leaves of Eriophorum vaginatum did not vary through the growing season but declined significantly after senescence. Application of N and P fertilizer in an experimental site decreased leaf toughness in three species but had no effect on four others. Leaf toughness of four out of five species in dry heath was greater than for the same species in tussock tundra, but there was no difference in community-weighted mean toughness between tussock tundra and dry heath. 

Abstract. Empirical in-situ measurements of ecosystem carbon dioxide respiration (Reco) in high-latitude ecosystems remain limited, yet they are essential for understanding how tundra carbon cycling responds to climate warming across different environmental contexts and for reducing uncertainties in upscaled carbon budgets and carbon–climate feedbacks. Here, we present the TundraFlux Database, which to date is the most comprehensive synthesis of tundra Reco responses to experimental warming. The database compiles over 24 000 daily-aggregated in-situ Reco measurements from control and warmed plots with open-top chambers at 64 Arctic and alpine tundra sites across 12 countries. By coupling Reco measurements with extensive metadata on climate, vegetation, and soil characteristics, the TundraFlux Database enables the integration of field-scale ecological processes into large-scale models, offering new opportunities to refine global carbon budgets and test predictions of tundra ecosystem responses to warming. Open access to the TundraFlux Database will empower the research community to better quantify and predict how warming alters carbon cycling in Arctic and alpine tundra ecosystems. The data can be accessed on Zenodo (https://doi.org/10.5281/zenodo.17976235, Schwieger, 2026a). 

The phenology of Arctic plants is an important determinant of the pattern of carbon uptake and may be highly sensitive to continued rapid climate change. Eriophorum vaginatum L. (Cyperaceae) has a disproportionate influence over ecosystem processes in moist acidic tundra, but it is unclear whether its growth and phenology will remain competitive in the future. We investigated whether northern tundra ecotypes of E. vaginatum could extend their growing season in response to direct warming and transplanting into southern ecosystems. At the same time, we examined whether southern ecotypes could adjust their growth patterns in order to thrive further north, should they disperse quickly enough. Detailed phenology measurements across three reciprocal transplant gardens over a 2-year period showed that some northern ecotypes were capable of growing for longer when conditions were favourable, but their biomass and growing season length was still shorter than those of the southern ecotype. Southern ecotypes retained large leaf length when transplanted north and mirrored the growing season length better than the others, mainly owing to immediate green-up after snowmelt. All ecotypes retained the same senescence timing, regardless of environment, indicating a strong genetic control. Eriophorum vaginatum may remain competitive in a warming world if southern ecotypes can migrate north.