Reforestation is a feasible option for the eventual restoration of biodiversity and ecosystem services on deforested oil‐sands mining sites. The associations between plant diversity and productivity spanning the different strata of restoration forests, in conjunction with specific factors that may impact these relationships, remain uncertain. We sampled 94 sites that encompassed conifer, mixed‐wood, and broadleaved overstory types as three exemplar substrates following the reforestation of oil‐sands mining sites in Alberta, Canada. We employed structural equation modeling to investigate the correlations between species diversity and aboveground biomass production spanning forest vegetation strata, while concurrently accounting for the effects of overstory composition, functional diversity/identity, soil fertility, and restoration age. We found that the relationships between species diversity and biomass were negative, or inconsequential across restoration forest strata. Overstory biomass was linked to the coniferous tree proportion and community‐weighted mean of leaf nitrogen, rather than the species and functional diversity of overstory trees. Further, overstory composition, diversity, and biomass were the key features involved in the diversity and biomass of understory strata. Our results demonstrated the importance of overstory tree species composition and selection effects toward driving overstory and understory productivity in restoration forests at post‐oil sands mining sites. Coniferous trees were observed to have lower leaf nutrient levels and negative impacts on the productivity and diversity of overstory and shrub layers. Therefore, it was recommended that a greater proportion of broadleaved trees should be incorporated to promote productivity and species diversity in restoration forests through the enhancement and utilization of available resources.

中文翻译：

---

树木种类的组成和选择效应驱动着重新造林的油砂矿开采区的林下和林下生产力

为了最终恢复被砍伐的油砂矿产地的生物多样性和生态系统服务，重新造林是一个可行的选择。跨越恢复森林不同层次的植物多样性与生产力之间的关联，以及可能影响这些关系的特定因素，仍然不确定。在加拿大艾伯塔省的油砂开采场重新造林之后，我们对94个包含针叶树，混合木材和阔叶表皮类型的场所进行了采样，作为三个典型的基质。我们采用结构方程模型来研究物种多样性与跨越森林植被地层的地上生物量生产之间的相关性，同时兼顾了超构成分，功能多样性/同一性，土壤肥力和恢复年龄的影响。我们发现，在恢复森林地层中，物种多样性与生物量之间的关系为负，或无关紧要。乔木的生物量与针叶树的比例和叶氮的社区加权平均值有关，而不与乔木的种类和功能多样性有关。此外，地层的组成，多样性和生物量是下层地层的多样性和生物量的关键特征。我们的结果表明，在油砂开采后的恢复森林中，过高的树种组成和选择效应对于提高过高和过低生产力的重要性。观察到针叶树的叶片养分含量较低，并且对过高的灌木层和灌木层的生产力和多样性产生负面影响。因此，