Snow redistribution decreases winter soil carbon loss in the Arctic dry heath tundra

• Published in: Agricultural and Forest Meteorology
• Main Authors: Liu, Yijing, Zhang, Wenxin, Danielsen, Birgitte Kortegaard, Elberling, Bo, Hansen, Birger U., Westergaard-Nielsen, Andreas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2024
• Subjects: Earth and Related Environmental Sciences; Ecology; Arctic tundra; Carbon budget; Snow redistribution; Soil temperature; Winter soil carbon dioxide efflux; Arctic; Greenland; Tundra
• Online Access: https://lup.lub.lu.se/record/457945e8-0ace-43fd-88fb-bedee50ada63; https://doi.org/10.1016/j.agrformet.2024.110158

Rapid warming increases winter soil carbon dioxide (CO2) efflux in Arctic tundra ecosystems, which can significantly offset carbon (C) uptake during growing seasons and affect the overall annual C balance. In winter, the Arctic landscape is predominantly covered with snow, which is vital for regulating ecological processes. Nevertheless, the impact of snow redistribution on the spatial distribution of winter soil CO2 efflux remains uncertain. In this study, we fitted an empirical model to quantify changes in total winter soil CO2 efflux based on accumulated snow depths, using in situ measurements from a snow manipulation experiment in a dry heath tundra ecosystem of Western Greenland. By employing a distributed snow model, we upscaled the spatial-temporal variations in winter soil CO2 efflux for a dry heath region of approx. 6 km2 during 2010–2020. We found that the total winter soil CO2 efflux increases linearly with the increasing total snow depth. In our study plots, the annual mean winter CO2 efflux ranged from 55 to 58 g C m−2 year−1 in ambient plots and 62 to 71 g C m−2 year−1 in snow addition plots (due to the snow fence) during 2013–2020. Spatially, wind-induced snow redistribution caused the annual mean winter CO2 efflux to vary from 51 to 76 g C m−2 year−1. Winter soil CO2 loss increased by 6 % if snow redistribution was not taken into account, primarily due to snow mass losses from the process of snow redistribution (such as blowing snow sublimation). Our results highlight the importance of snow redistribution on winter soil CO2 emissions, particularly when using regional land models in predictions of annual C balance in the Arctic ecosystems under a changing climate.