Global climatic change indicates that some climate systems have passed tipping points, e.g. the inner East Asia; however it's still uncertain when the tipping point of forest mortality could be triggered. Absent rings are early warnings of irreversible mortality. They widely exist in Northern Hemisphere forests, but they're locally rare and under-discussed in previous studies. We reported a tree ring network, including 17 collections among the extensive distribution of Pinus tabuliformis in North China. Locally absent rings (LAR) were counted and logistic models were built to determine biotic and abiotic driving forcings of LAR. Pinus tabuliformis suffered increasing LAR frequency in recent decades, and the highest LAR frequency occurred at the driest distributional margin. At the semi-arid region, LAR frequency increased along with increasing age, decreasing previous September moisture, and decreasing May moisture. LAR risk would gradually increase, and older trees would suffer quite high LAR risk in the future. We highlight the connection between frequent LAR and extreme droughts in semi-arid pine forests, and propose that LAR can be a proxy of the potential tipping points of forest systems.

全球气候变化表明一些气候系统已经过了临界点，例如东亚内陆地区；然而，何时会触发森林死亡率的临界点仍不确定。没有戒指是不可逆转死亡的早期警告。它们广泛存在于北半球的森林中，但它们在当地很少见，并且在以前的研究中讨论不足。我们报告了一个年轮网络，包括华北油松广泛分布的 17 个集合。计算局部缺失环 (LAR) 并建立逻辑模型以确定 LAR 的生物和非生物驱动力。油松近几十年来 LAR 频率不断增加，最高的 LAR 频率发生在最干燥的分布边缘。在半干旱地区，LAR 频率随着年龄的增加而增加，9 月水分减少，5 月水分减少。LAR 风险会逐渐增加，老树将来会遭受相当高的 LAR 风险。我们强调了半干旱松林中频繁的 LAR 与极端干旱之间的联系，并建议 LAR 可以代表森林系统的潜在临界点。