Wood‐Based Carbon Storage in the Mackenzie River Delta: The World's Largest Mapped Riverine Wood Deposit

Abstract

Carbon-rich organic matter associated with large wood (LW, pieces >10 cm in diameter and 1 m in length) transported by rivers has remained an unconstrained component of carbon cycling estimates, in terms of its stock in the landscape, residence time, and flux . Arctic rivers account for ∼15% of global drainage area and, although much of this area is not forested, there is evidence for long-term wood storage in Arctic environments (Müller, 1962) and supply of driftwood to coastal and marine environments. For example, recent work demonstrates widespread transport of wood supplied by rivers across the Arctic Ocean (Hole et al., 2021). Across the Arctic, permafrost regions currently contain more stored carbon than is in the atmosphere (Schuur et al., 2015), with Arctic deltas containing 91 × 10 15 g-C stored in permafrost soils (Hugelius et al., 2014). With climate change expected to increase rates of permafrost thaw that will increase erosion rates (Lininger & Wohl, 2019), modifying delta channel networks, floodplains, and carbon fluxes and ultimately releasing legacy carbon stored in deltas (Schuur et al., 2015), previous work on carbon cycling by Arctic rivers has only focused on characterizing the source, age, and transfer of dissolved carbon species (