Project Funding: 2015 - 2020

NRA: 2014 NASA: Terrestrial Ecology   

Funded by NASA

Abstract:
The Yukon-Kuskokwim Delta (Y-K Delta) region of western Alaska is one of the most biologically productive areas of the tundra biome and supports one of the largest indigenous human populations in the circumpolar Arctic. Most of the region's 57 Yup'ik communities are highly reliant on terrestrial subsistence resources, such as the Y-K Delta's exceptional breeding populations of migratory geese and other waterbirds. The future sustainability of community infrastructure is uncertain due to changing dynamics of climate, coasts, rivers, and permafrost. Notably, large areas of the Y-K Delta lie very near sea-level, and much of the region is underlain by relatively warm permafrost that is highly susceptible to thaw as temperatures warm. Sea-level rise, sea-ice loss, and expected changes in the frequency and intensity of storms make coastal ecosystems and infrastructure especially vulnerable. Satellite and field-based observations on land and adjacent waters of the Bering Sea indicate that the Y-K Delta has already undergone widespread environmental change in recent decades. Satellite-observed trends of the Normalized Difference Vegetation Index (NDVI) in the Y-K Delta since the mid-1990s are highly idiosyncratic relative to circumpolar trends, with coarse-scale (12.5 km) time-series indicating strong declines in the productivity of tundra vegetation ('browning'). Regional browning in the Y-K Delta contrasts starkly with widespread 'greening' trends observed in northern Alaska and elsewhere in the circumpolar Arctic. Yet, the changes to vegetation and their links to regional-scale climate drivers, and intensified landscape-scale disturbance regimes are poorly understood, despite the strong relationships between direct impacts of environmental change to ecosystem services and human well-being in the region. The multi-disciplinary work proposed here integrates remote-sensing, field-based, and sociological approaches to address environmental change and socio-ecological impacts in the Y-K Delta region. Notably, all phases of the project will be informed by quantitative, repeat sampling of vegetation, soil, hydrology, and permafrost properties across a long-term monitoring plot network that was established in the mid-1990s and is well-suited for validating multi-temporal remote-sensing datasets. Specific objectives are to (1) elucidate links between the productivity of Y-K Delta ecosystems and regional-scale atmospheric and cryospheric climate drivers; (2) resolve the spatial extent and drivers of long-term changes in vegetation and physical landscape properties related to landscape-scale disturbance processes; (3) characterize changes in the composition and structure of tundra vegetation across a network of long-term monitoring plots; and (4) relate the observed changes to local observations and concerns regarding environmental change, impacts to ecosystem services, and community sustainability. The proposed work will occur in three phases over four years. In 2015, research activities will focus on analysis of multi-decadal remote-sensing data time series, and retrospective studies of historical and contemporary high-resolution imagery. Results of the remote-sensing analysis will be used to design and implement a ground-based data collection effort focused on vegetation, soils, hydrology, and permafrost across environmental gradients near two Yup'ik population centers: the central coast region near Chevak (2017) and the Yukon Delta near Emmonak (2018). In 2018, work will focus on applying findings to address the concerns and needs for information identified by stakeholders and land managers. The project will leverage detailed long-term field datasets, as well as data products generated from recently-completed vegetation mapping and remote-sensing analysis efforts in western Alaska.

Publications:

2020. State of the Climate in 2019. Bulletin of the American Meteorological Society. 101(8), S1-S429. DOI: 10.1175/2020BAMSStateoftheClimate.1

Bartsch, A., Widhalm, B., Leibman, M., Ermokhina, K., Kumpula, T., Skarin, A., Wilcox, E. J., Jones, B. M., Frost, G. V., Hofler, A., Pointner, G. 2020. Feasibility of tundra vegetation height retrieval from Sentinel-1 and Sentinel-2 data. Remote Sensing of Environment. 237, 111515. DOI: 10.1016/j.rse.2019.111515

Beamish, A., Raynolds, M. K., Epstein, H., Frost, G. V., Macander, M. J., Bergstedt, H., Bartsch, A., Kruse, S., Miles, V., Tanis, C. M., Heim, B., Fuchs, M., Chabrillat, S., Shevtsova, I., Verdonen, M., Wagner, J. 2020. Recent trends and remaining challenges for optical remote sensing of Arctic tundra vegetation: A review and outlook. Remote Sensing of Environment. 246, 111872. DOI: 10.1016/j.rse.2020.111872

Bhatt, U. S., Walker, D. A., Raynolds, M. K., Bieniek, P. A., Epstein, H. E., Comiso, J. C., Pinzon, J. E., Tucker, C. J., Steele, M., Ermold, W., Zhang, J. 2017. Changing seasonality of panarctic tundra vegetation in relationship to climatic variables. Environmental Research Letters. 12(5), 055003. DOI: 10.1088/1748-9326/aa6b0b

Bhatt, U. S., Walker, D. A., Raynolds, M. K., Walsh, J. E., Bieniek, P. A., Cai, L., Comiso, J. C., Epstein, H. E., Frost, G. V., Gersten, R., Hendricks, A. S., Pinzon, J. E., Stock, L., Tucker, C. J. 2021. Climate drivers of Arctic tundra variability and change using an indicators framework. Environmental Research Letters. 16(5), 055019. DOI: 10.1088/1748-9326/abe676

Frost, G. V., Bhatt, U. S., Macander, M. J., Hendricks, A. S., Jorgenson, M. T. 2021. Is Alaska's Yukon-Kuskokwim Delta Greening or Browning? Resolving Mixed Signals of Tundra Vegetation Dynamics and Drivers in the Maritime Arctic. Earth Interactions. 25(1), 76-93. DOI: 10.1175/EI-D-20-0025.1

Frost, G. V., Loehman, R. A., Saperstein, L. B., Macander, M. J., Nelson, P. R., Paradis, D. P., Natali, S. M. 2020. Multi-decadal patterns of vegetation succession after tundra fire on the Yukon-Kuskokwim Delta, Alaska. Environmental Research Letters. 15(2), 025003. DOI: 10.1088/1748-9326/ab5f49

Frost, G. V., U. S. Bhatt, H. E. Epstein, D. A. Walker, M. K. Raynolds, L. T. Berner, J. W. Bjerke, A. L. Breen, B. C. Forbes, S. J. Goetz, C. M. Iversen, M. J. Lara, M. J. Macander, G. K. Phoenix, A. V. Rocha, V. G. Salmon, P. E. Thornton, H. Tømmervik, and S. D. Wullschleger. 2019. Tundra greenness. Arctic Report Card 2019, J. Richter-Menge, M. L. Druckenmiller, and M. Jeffries (Eds.). http://www.arctic.noaa.gov/Report-Card.

Frost, G. V., U. S. Bhatt, H. E. Epstein, I. Myers-Smith, G. K. Phoenix, L. T. Berner, J. W. Bjerke, B. C. Forbes, M. J. Macander, S. J. Goetz, J. T. Kerby, T. Park, M. K. Raynolds, H. Tømmervik, and D. A. Walker. 2020. Tundra greenness. Arctic Report Card 2020, J. Richter-Menge, M. L. Druckenmiller, and M. Jeffries (Eds.). DOI: 10.25923/46rm-0w23.

Hendricks, A. S., Bhatt, U. S., Frost, G. V., Walker, D. A., Bieniek, P. A., Raynolds, M. K., Lader, R. T., Epstein, H. E., Pinzon, J. E., Tucker, C. J., Comiso, J. C. 2023. Decadal variability in spring sea-ice concentration linked to summer temperature and NDVI on the Yukon-Kuskokwim Delta. Earth Interactions. DOI: 10.1175/EI-D-23-0002.1

Jorgenson, M., Frost, G., Dissing, D. 2018. Drivers of Landscape Changes in Coastal Ecosystems on the Yukon-Kuskokwim Delta, Alaska. Remote Sensing. 10(8), 1280. DOI: 10.3390/rs10081280

Raynolds, M. K., Walker, D. A., Balser, A., Bay, C., Campbell, M., Cherosov, M. M., Daniels, F. J., Eidesen, P. B., Ermokhina, K. A., Frost, G. V., Jedrzejek, B., Jorgenson, M. T., Kennedy, B. E., Kholod, S. S., Lavrinenko, I. A., Lavrinenko, O. V., Magnusson, B., Matveyeva, N. V., Metusalemsson, S., Nilsen, L., Olthof, I., Pospelov, I. N., Pospelova, E. B., Pouliot, D., Razzhivin, V., Schaepman-Strub, G., Sibik, J., Telyatnikov, M. Y., Troeva, E. 2019. A raster version of the Circumpolar Arctic Vegetation Map (CAVM). Remote Sensing of Environment. 232, 111297. DOI: 10.1016/j.rse.2019.111297

Whitley, M., Frost, G., Jorgenson, M., Macander, M., Maio, C., Winder, S. 2018. Assessment of LiDAR and Spectral Techniques for High-Resolution Mapping of Sporadic Permafrost on the Yukon-Kuskokwim Delta, Alaska. Remote Sensing. 10(2), 258. DOI: 10.3390/rs10020258

More details may be found in the following project profile(s):

• NASA Terrestrial Ecology (TE) Project Profile
• NASA Arctic-Boreal Vulnerability Experiment (ABoVE) Project Profile