New recruit at the tree line

New needles emerge from a year‐old Larix laricina seedling at the alpine tree line in Newfoundland, Canada, following its first winter. This boreal conifer is widely distributed across North America, often occurring as a co‐dominant species at boreal forest range limits. The treeline ecotone – the transition between forest and alpine or tundra ecosystems – is commonly recognized as a thermal boundary and represents the uppermost altitudinal and greatest latitudinal conditions that can support tree growth, survival, and reproduction. Treeline populations of L laricina, and other treeline‐forming boreal conifers, are expected to advance upslope and to greater latitudes in response to increasing atmospheric temperatures. Treeline advance must initially depend on increased recruitment, the production or dispersal of viable seeds followed by seedling establishment and survival at or beyond current range limits. Although there has been no ubiquitous response to atmospheric warming among other boreal conifer tree genera, evidence suggests that recruitment of Larix spp at the tree line has increased. Differential responses between co‐dominant tree species will result in the formation of novel treeline communities, which will likely have critical implications for treeline ecotone structure and function. Will these changes promote or inhibit climate‐change effects on boreal tree distribution