Sufficient conditions for rapid range expansion of a boreal conifer

Dial, Roman J.
Maher, Colin T.
Hewitt, Rebecca E.
Sullivan, Patrick F.
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Springer Nature
Unprecedented modern rates of warming are expected to advance boreal forest into Arctic tundra, thereby reducing albedo, altering carbon cycling and further changing climate, yet the patterns and processes of this biome shift remain unclear. Climate warming, required for previous boreal advances, is not sufficient by itself for modern range expansion of conifers forming forest–tundra ecotones. No high-latitude population of conifers, the dominant North American Arctic treeline taxon, has previously been documented advancing at rates following the last glacial maximum (LGM). Here we describe a population of white spruce (Picea glauca) advancing at post-LGM rates across an Arctic basin distant from established treelines and provide evidence of mechanisms sustaining the advance. The population doubles each decade, with exponential radial growth in the main stems of individual trees correlating positively with July air temperature. Lateral branches in adults and terminal leaders in large juveniles grow almost twice as fast as those at established treelines. We conclude that surpassing temperature thresholds, together with winter winds facilitating long-distance dispersal, deeper snowpack and increased soil nutrient availability promoting recruitment and growth, provides sufficient conditions for boreal forest advance. These observations enable forecast modelling with important insights into the environmental conditions converting tundra into forest.
© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit The Version of Scholarly Record of this Article is published in Nature, 2022, available online at: Keywords: tundra; boreal forest; white spruce; Picea glauca; climate change.
Dial, R.J., Maher, C.T., Hewitt, R.E. et al. Sufficient conditions for rapid range expansion of a boreal conifer. Nature 608, 546–551 (2022).