With climate change, climatic optima are shifting poleward more rapidly than tree migration processes, resulting in a mismatch between species distributions and bioclimatic envelopes. Temperate hardwood tree species may take advantage of the release of climate constraints and forest management to migrate into the boreal forest. Here, we use the SORTIE-ND forest simulation model to determine the potential for the persistence of three temperate species (sugar maple, red maple and yellow birch) when introduced at seedling stage in typical balsam fir–paper birch (BF–PB) bioclimatic domain stands of eastern Canada, quantifying the consequences on the native species composition. SORTIE-ND is a spatially explicit, individual-based forest stand model that simulates tree growth, regeneration and mortality. We performed a novel parameterization of the SORTIE-ND tree growth equation allowing for the inclusion of climate modifiers on tree growth. After validating our model with data from permanent forest inventory plots, we modeled the dynamics of unharvested stands at different successional stages, as well as post-harvest stands, after the addition of sugar maple, red maple and yellow birch seedlings at different densities. Our results show that current BF–PB domain climate conditions do not limit growth and survival of temperate species in boreal stands. Of the temperate species introduced, sugar maple had the lowest ability to grow and survive by the end of the simulation. Species assemblages of host stands were impacted by the presence of temperate species when the addition of seedlings was above 5000 temperate seedlings per hectare at the beginning of the simulation. For stands that were recently clear cut, temperate seedlings were unable to grow due to intense competition from aspen regeneration. Our results suggest that both current climate and competitive interactions between temperate species and boreal species should not impede the ability of temperate species to grow and survive in the BF–PB domain.

中文翻译：

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当前气候下的竞争性相互作用使温带树种能够在北方混交林中生长和生存

随着气候变化，气候最佳状态向极地移动的速度比树木迁移过程更快，导致物种分布与生物气候范围之间的不匹配。温带硬木树种可能会利用气候限制的释放和森林管理迁移到北方森林。在这里，我们使用 SORTIE-ND 森林模拟模型来确定三种温带物种（糖枫、红枫和黄桦）在幼苗阶段引入典型香脂冷杉-纸桦 (BF-PB) 生物气候条件下的持久性潜力加拿大东部的域林，量化对本地物种组成的影响。SORTIE-ND 是一种空间明确的、基于个体的林分模型，可模拟树木的生长、再生和死亡率。我们对 SORTIE-ND 树木生长方程进行了新的参数化，允许在树木生长中加入气候调节剂。在使用永久性森林清查地块的数据验证我们的模型后，我们模拟了不同演替阶段未采伐林分的动态，以及在添加不同密度的糖枫、红枫和黄桦幼苗后采伐后的林分动态。我们的结果表明，目前的 BF-PB 域气候条件不会限制北方林分中温带物种的生长和生存。在引入的温带物种中，糖枫在模拟结束时的生长和存活能力最低。当模拟开始时每公顷添加的幼苗超过 5000 株温带幼苗时，寄主林分的物种组合会受到温带物种存在的影响。对于最近被砍伐的林分，由于白杨再生的激烈竞争，温带幼苗无法生长。我们的结果表明，当前的气候和温带物种与寒带物种之间的竞争相互作用不应阻碍温带物种在 BF-PB 域中生长和生存的能力。