Soil pH, salinity, thaw depth, and respiration during summer 2023 in small plots near Old Chevak, Alaska that were either flooded, not flooded, or contained fine debris deposited by Typhoon Merbok

In September 2022, a typhoon struck western Alaska with a storm surge exceeding 4 meters (m). Coastal portions of the Yukon-Kuskokwim (Y-K) Delta, the second largest river delta in North America, were submerged under water from the Bering Sea for many hours. The Y-K Delta is composed of seaward ecosystems characterized by tidal flooding and contain mesohaline soils, and inland permafrost plateaus with oligohaline soils flooded only by storm surge. The highest elevation ecosystems are low Arctic tundra with plant species intolerant of flooding and saltwater intrusion. Fine debris was observed on the permafrost plateau, with tundra vegetation on either side of the debris line suggesting extensive areas of tundra were flooded. At each of six sites near Old Chevak, Alaska, we established plots on flooded and non-flooded tundra, and on the fine debris line as an indication of the high-water mark associated with the typhoon. We measured thaw depth, soil salinity, pH, and soil respiration to quantify flood impacts on soils. We also collected fine debris from these plots and other debris deposits in the region and analyzed the debris for carbon (C) and nitrogen (N) content. Here we share soil data from 9 July 2023, soil respiration and methane emissions data from eight days between the end of June and the beginning of August 2023, and analysis of debris collected at various times during summer 2023.