Project Funding: 2015 - 2022

NRA: 2014 NASA: Terrestrial Ecology   

Funded by NASA

Abstract:
2019 Augmentation SOW Background Carbon stored in northern high latitude soils, including those within the NASA Arctic Boreal Vulnerability Experiment (ABoVE) domain, is increasingly vulnerable to microbial mineralization and transfer to the atmosphere as CO2. Climate warming at high latitudes is expected to be most pronounced during shoulder and winter seasons over the next century (Pithan & Mauritsen 2014). The amount of CO2 released from northern soils is not well understood, particularly for shoulder (autumn, spring) and winter seasons. This lack of understanding remains problematic for assessments of net ecosystem carbon budgets within the pan-Arctic domain, which may be underestimating soil CO2 emissions. Recent field studies indicate that CO2 release from warming northern soils can offset growing season carbon (C) gains and shift ecosystem carbon budgets from a net sink to a net source (Natali et al., 2014). Regional analyses, including a study examining flux observations from tower and aircraft at Utqiaġvik (Barrow), Alaska, report that CO2 emission rates have increased by 73% during the early winter (October through December) period since 1975 (Commane et al., 2017). Another study found that current satellite remote sensing detection of atmospheric CO2 does not provide sufficient detection in the Alaska cold season, and that airborne surveys lack the spatial coverage necessary to quantify regional CO2 emissions (Parazoo et al., 2016). Attempts to use Earth System Models (ESMs) to quantify northern cold season emissions have produced inconclusive, and often conflicting, results. A model intercomparison for the ABoVE region reported that the ESMs showed considerable variability in estimates of CO2 loss during the winter season (Fisher et al., 2014). A more recent study for the pan-Arctic (Natali et al., In Revision) also found that most ESMs underestimated soil CO2 loss in shoulder and winter seasons. Another model-based study (Liu et al., In Review) for Alaska reported that a critical knowledge gap in northern carbon cycle science was the ability to understand and attribute seasonal changes in component carbon fluxes (e.g., vegetation productivity vs. soil respiration) and how the magnitudes of these sources change over time and space in response to key environmental drivers (e.g., temperature, moisture, and vegetation). Improving our understanding of these emissions is extremely important to: 1) diagnose terrestrial carbon sink/source activity in the ABoVE region; 2) identify the underlying ecosystem conditions enhancing or mitigating soil CO2 loss; 3) understand the role of fire disturbance on soil CO2 emissions; 4) improve temperature response functions for cold temperature conditions in ESMs. Overcoming this knowledge gap requires in situ observations of warm and cold season CO2 emissions within the ABoVE domain across gradients of permafrost, vegetation, soil moisture and disturbance conditions. Original Abstract: This proposal addresses the Tier 2 Science Question (3.6) of the Terrestrial Ecology solicitation (A.4): 'How are the magnitudes, fates, and land-atmosphere exchanges of carbon pools responding to environmental change, and what are the biogeochemical mechanisms driving these changes?' Over the past decades, surface air temperatures in the Arctic have increased at approximately twice the global rate, and climate models project that this rate of warming will continue through the century, with the greatest warming occurring during the winter months. An increase in wintertime temperature may reduce belowground carbon storage due to enhanced microbial respiration during the snow-covered period. Carbon dioxide (CO2) emissions during the winter and shoulder seasons (fall and spring) are an important component of annual respiratory loss, yet there is large uncertainty in local and regional estimates of CO2 emissions during the non-growing season. Carbon losses during the snow covered period can be as great as or equal to net growing season carbon uptake, shifting tundra ecosystems from carbon sinks during the growing season to sources on an annual basis. Therefore, refining winter respiration estimates and understanding the drivers of winter respiration are critical for understanding current and future carbon emissions from the Arctic. The objectives of this proposal are to 1.) measure winter respiration continuously at sites across the permafrost region, 2) examine the drivers of winter respiration, and 3) combine field measurements with remotely sensed data sets and products to estimate regional CO2 emissions during the non-growing season. We will instrument sites across the ABoVE study domain with newly-developed forced diffusion soil efflux sensors (FDs), a low-power technique with high temporal resolution and high reliability for harsh deployment environments. We will also collect continuous automated measurements of key environmental drivers (e.g., air temperature, snow cover, soil moisture, soil temperature) and measure vegetation and soil characteristics at the plot level, and we will extend plot-level measurements of respiration drivers to larger spatial scales consistent with satellite remote sensing data retrievals. Sites will be selected to span the range of permafrost regions from continuous to sporadic to allow us to address questions about winter respiration under different thaw regimes, including those influenced by fire disturbance and related thermal erosion, changes in active layer depth, and thermokarst. The site-level flux measurements will be used with a range of existing multi-scale satellite data sets and products, as well as newly generated products where needed (particularly outside the growing season), to scale the field measurements spatially and temporally, thereby estimating CO2 emissions from winter respiration across the landscape. Linking to satellite data sets will be done primarily via indirect proxies such as vegetation properties (cover, density, composition) and land surface temperature. Additional landscape variables such as topography, soil properties and surficial geology will also be used as predictor variables in spatially explicit statistical ensemble models (i.e. RandomForest). Image segmentation approaches will also be used as a means to associate field measurements with spatial data and scale to the landscape.

Publications:

Liu, Z., Kimball, J. S., Ballantyne, A. P., Parazoo, N. C., Wang, W. J., Bastos, A., Madani, N., Natali, S. M., Watts, J. D., Rogers, B. M., Ciais, P., Yu, K., Virkkala, A., Chevallier, F., Peters, W., Patra, P. K., Chandra, N. 2022. Respiratory loss during late-growing season determines the net carbon dioxide sink in northern permafrost regions. Nature Communications. 13(1). DOI: 10.1038/s41467-022-33293-x

Natali, S. M., Watts, J. D., Rogers, B. M., Potter, S., Ludwig, S. M., Selbmann, A., Sullivan, P. F., Abbott, B. W., Arndt, K. A., Birch, L., Bjorkman, M. P., Bloom, A. A., Celis, G., Christensen, T. R., Christiansen, C. T., Commane, R., Cooper, E. J., Crill, P., Czimczik, C., Davydov, S., Du, J., Egan, J. E., Elberling, B., Euskirchen, E. S., Friborg, T., Genet, H., Gockede, M., Goodrich, J. P., Grogan, P., Helbig, M., Jafarov, E. E., Jastrow, J. D., Kalhori, A. A. M., Kim, Y., Kimball, J. S., Kutzbach, L., Lara, M. J., Larsen, K. S., Lee, B., Liu, Z., Loranty, M. M., Lund, M., Lupascu, M., Madani, N., Malhotra, A., Matamala, R., McFarland, J., McGuire, A. D., Michelsen, A., Minions, C., Oechel, W. C., Olefeldt, D., Parmentier, F. W., Pirk, N., Poulter, B., Quinton, W., Rezanezhad, F., Risk, D., Sachs, T., Schaefer, K., Schmidt, N. M., Schuur, E. A. G., Semenchuk, P. R., Shaver, G., Sonnentag, O., Starr, G., Treat, C. C., Waldrop, M. P., Wang, Y., Welker, J., Wille, C., Xu, X., Zhang, Z., Zhuang, Q., Zona, D. 2019. Large loss of CO2 in winter observed across the northern permafrost region. Nature Climate Change. 9(11), 852-857. DOI: 10.1038/s41558-019-0592-8

Schiferl, L. D., Watts, J. D., Larson, E. J. L., Arndt, K. A., Biraud, S. C., Euskirchen, E. S., Henderson, J. M., McKain, K., Mountain, M. E., Munger, J. W., Oechel, W. C., Sweeney, C., Yi, Y., Zona, D., Commane, R. Using atmospheric observations to quantify annual biogenic carbon dioxide fluxes on the Alaska North Slope DOI: 10.5194/bg-2022-167

Virkkala , A., Natali, S. M., Rogers, B. M., Watts, J. D., Savage, K., Connon, S. J., Mauritz, M., Schuur, E. A. G., Peter, D., Minions, C., Nojeim, J., Commane, R., Emmerton, C. A., Goeckede, M., Helbig, M., Holl, D., Iwata, H., Kobayashi, H., Kolari, P., Lopez-Blanco, E., Marushchak, M. E., Mastepanov, M., Merbold, L., Parmentier, F. W., Peichl, M., Sachs, T., Sonnentag, O., Ueyama, M., Voigt, C., Aurela, M., Boike, J., Celis, G., Chae, N., Christensen, T. R., Bret-Harte, M. S., Dengel, S., Dolman, H., Edgar, C. W., Elberling, B., Euskirchen, E., Grelle, A., Hatakka, J., Humphreys, E., Jarveoja, J., Kotani, A., Kutzbach, L., Laurila, T., Lohila, A., Mammarella, I., Matsuura, Y., Meyer, G., Nilsson, M. B., Oberbauer, S. F., Park, S., Petrov, R., Prokushkin, A. S., Schulze, C., St. Louis, V. L., Tuittila, E., Tuovinen, J., Quinton, W., Varlagin, A., Zona, D., Zyryanov, V. I. 2022. The ABCflux database: Arctic-boreal CO<sub>2</sub> flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems. Earth System Science Data. 14(1), 179-208. DOI: 10.5194/essd-14-179-2022

Watts, J. D., Natali, S. M., Minions, C., Risk, D., Arndt, K., Zona, D., Euskirchen, E. S., Rocha, A. V., Sonnentag, O., Helbig, M., Kalhori, A., Oechel, W., Ikawa, H., Ueyama, M., Suzuki, R., Kobayashi, H., Celis, G., Schuur, E. A. G., Humphreys, E., Kim, Y., Lee, B., Goetz, S., Madani, N., Schiferl, L. D., Commane, R., Kimball, J. S., Liu, Z., Torn, M. S., Potter, S., Wang, J. A., Jorgenson, M. T., Xiao, J., Li, X., Edgar, C. 2021. Soil respiration strongly offsets carbon uptake in Alaska and Northwest Canada. Environmental Research Letters. 16(8), 084051. DOI: 10.1088/1748-9326/ac1222

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

• NASA Terrestrial Ecology (TE) Project Profile
• North American Carbon Program (NACP) Project Profile
• NASA Arctic-Boreal Vulnerability Experiment (ABoVE) Project Profile