Tropical cloud forests (TCFs) are one of the world’s most species- and endemism-rich terrestrial ecosystems. TCFs are threatened by direct human pressures and climate change, yet the fate of these extraordinary ecosystems remains insufficiently quantified. With discussions of the post-2020 biodiversity framework underway, TCFs are a defining test case of the success and promise of recent policy targets and their associated mechanisms to avert the global biodiversity crisis. Here we present a global assessment of the recent status and trends of TCFs and their biodiversity and evaluate the efficacy of current protection measures. We find that cloud forests occupied 0.4% of the global land surface in 2001 and harboured ~3,700 species of birds, mammal, amphibians and tree ferns (~15% of the global diversity of those groups), with half of those species entirely restricted to cloud forests. Worldwide, ~2.4% of cloud forests (in some regions, more than 8%) were lost between 2001 and 2018, especially in readily accessible places. While protected areas have slowed this decline, a large proportion of loss in TCF cover is still occurring despite formal protection. Increased conservation efforts are needed to avert the impending regional or global demise of TCFs and their unique biodiversity.

热带云雾林 (TCF) 是世界上物种和特有性最丰富的陆地生态系统之一。TCF 受到人类直接压力和气候变化的威胁，但这些非凡生态系统的命运仍未得到充分量化。随着对 2020 年后生物多样性框架的讨论正在进行中，TCF 是近期政策目标及其相关机制在避免全球生物多样性危机方面取得成功和前景的决定性测试案例。在这里，我们对 TCF 及其生物多样性的近期状况和趋势进行了全球评估，并评估了当前保护措施的有效性。我们发现，2001 年，云雾林占全球陆地表面的 0.4%，栖息着约 3,700 种鸟类、哺乳动物、两栖动物和树蕨（约占这些群体全球多样性的 15%），这些物种中有一半完全局限于云雾林。2001 年至 2018 年间，全球约有 2.4% 的云雾林（在某些地区，超过 8%）消失，尤其是在交通便利的地方。虽然保护区减缓了这种下降，但尽管有正式的保护，TCF 覆盖面的很大一部分损失仍在发生。需要加强保护工作，以避免 TCF 及其独特的生物多样性即将在区域或全球消亡。