Journal ArticleLinking Post-fire Tree Density to Carbon Storage in High-Latitude Cajander Larch (Larix cajanderi) Forests of Far Northeastern SiberiaAlexander, H D; Paulson, A K; Loranty, M M; Mack, M C; Natali, S M; Pena, H; Davydov, S; Spektor, V; Zimov, N<title>Abstract</title> <p>With climate warming and drying, fire activity is increasing in Cajander larch (<italic>Larix cajanderi</italic>Mayr.) forests underlain by continuous permafrost in northeastern Siberia, and initial post-fire tree demographic processes could unfold to determine long-term forest carbon (C) dynamics through impacts on tree density. Here, we evaluated above- and belowground C pools across 25 even-aged larch stands of varying tree densities that established following a wildfire in ~ 1940 near Cherskiy, Russia. Total C pools increased with increased larch tree density, from ~ 9,000 g C m⁻²in low-density stands to ~ 11,000 g C m⁻²in high and very high-density stands, with increases most pronounced at tree densities < 1 stem m⁻²and driven by increased above- and belowground (that is, coarse roots) and live and dead (that is, woody debris and snags) larch biomass. Total understory vegetation and non-larch coarse root C pools declined with increased tree density due to decreased shrub C pools, but these pools were relatively small compared to larch biomass. Fine root, soil organic matter (OM), and near surface (0–30 cm) mineral soil (MS) C pools varied little with tree density, although soil C pools held most (18–28% in OM and 44–51% in MS) C stored in these stands. Thus, if changing fire regimes promote denser stands, C storage will likely increase, but whether this increase offsets C lost during fires remains unknown. Our findings highlight how post-fire tree demographic processes impact C pool distribution and stability in larch forests of Siberian permafrost regions.</p>Ecosystems2024-08-0110541881Ecosystems275655 to 6721432-9840https://doi.org/10.1007/s10021-024-00913-02100773; 2116862; 2116864National Science Foundation