Abstract：
Species interactions such as facilitation and competition play a crucial role in driving species range shifts. However, density dependence as a key feature of these processes has received little attention in both empirical and modelling studies. Herein, we used a novel, individual-based treeline model informed by rich in situ observations to quantify the contribution of density-dependent species interactions to alpine treeline dynamics, an iconic biome boundary recognized as an indicator of global warming. We found that competition and facilitation dominate in dense versus sparse vegetation scenarios respectively. The optimal balance between these two effects was identified at an intermediate vegetation thickness where the treeline elevation was the highest. Furthermore, treeline shift rates decreased sharply with vegetation thickness and the associated transition from positive to negative species interactions. We thus postulate that vegetation density must be considered when modelling species range dynamics to avoid inadequate predictions of its responses to climate warming.
摘要：
诸如促进和竞争之类的物种相互作用在驱动物种范围变化中起着至关重要的作用。然而,密度依赖性作为这些过程的关键特征，在实证和建模研究中都很少受到关注。在这里，我们用了一本小说,基于个体的树线模型通过丰富的原位观察来量化密度依赖性物种相互作用对高山树线动力学的贡献，被认为是全球变暖指标的标志性生物群落边界。我们发现，在密集和稀疏的植被情景中，竞争和促进分别占主导地位。在树线海拔最高的中等植被厚度处确定了这两种效应之间的最佳平衡。此外，随着植被厚度以及相关的从正物种相互作用到负物种相互作用的过渡，树线移位率急剧下降。因此，我们假设在对物种范围动态进行建模时必须考虑植被密度，以避免对其对气候变暖的响应的预测不足。
