Climate variability and growth competition in an arctic-alpine ecosystem: retrospective growth analyses of one deciduous and one evergreen dwarf shrub in the Norwegian Scandes

高山生态系统被认为容易受到气候变化的影响。在特定恶劣条件下进化的物种可能在变暖条件下失去竞争能力，导致物种分布范围的转移和高寒生态系统的结构变化，并在某些地区最终导致目前生长在高寒上带的物种被生长在高寒下带的物种所取代。回顾性增长分析支持对未来全球变暖下高山生态系统命运的预测。在上高寒带，木本矮灌木是生态系统的骨干。作为乔木，矮灌木形成年轮，近年来，矮灌木的树木生态学已成为一个新兴的、有发展前景的科学领域。在这里，我们的目的是分析两种物种（一种落叶和一种常绿）的生长时间、气候-生长相互作用和竞争，以挪威斯坎德斯山脉一个典型的低高山山脊为例。这将通过构建环宽年表（每个物种一个年表），并将这些生长时间序列与独特的、长期的、特定地点的微气候记录和区域气候记录进行统计比较来完成。通过回顾性生长分析，研究物种对过去和正在进行的气候变率的响应，揭示物种对当地气候包络的敏感性以及气候变率对其竞争的影响。通过这种方式，它们未来的生长对气候站点条件变化的响应可以量化，我们对北极-高山生态系统对气候变化的脆弱性的理解将会增加。

Alpine ecosystems are regarded as vulnerable to climate change. Species evolved under specific harsh conditions might lose their competitive ability under warming conditions, resulting in range shifts in the species distribution, structural alterations of alpine ecosystems, and in certain areas, ultimately, a replacement of species currently growing in the upper alpine belts with those from the lower alpine belts. Retrospective growth analyses support predictions of the fate of alpine ecosystems under future global warming. In the upper alpine belts woody dwarf shrubs species form the backbone of the ecosystem. As trees, such shrubs form annual growth rings, and in recent years dendroecology of (dwarf) shrubs has emerged as a new and promising scientific field. Here, we aim to analyze the timing of growth of, climate-growth interactions in, and competition between two species, one deciduous and one evergreen, as example of a characteristic low alpine ridge site in the Norwegian Scandes. This will be done through the construction of ring-width chronologies (one for each species) and the statistical comparison of these growth time-series with both a unique, long-term, site specific, micro-climatic record and the regional climate record. By studying the species response to past and ongoing climate variability through retrospective growth analyses, the susceptibility of the species to their local climate envelope and the influence of climate variability on their competition will be revealed. This way, their future growth response to modified climatic site conditions can be quantified and our understanding of the vulnerability of arctic-alpine ecosystems to climate change will increase.