Fog is an important component of the coastal climate of northern Chile and southern Peru. Moisture and nutrients from fog maintain highly endemic vegetation (lomas) as well as unique ecosystems that thrive at elevations of ca. 900–1200 m asl. Although this epiphytic CAM bromeliad is well adapted to the extreme climate, declining stocks observed over the past decades question the long-term survival with ongoing climate change. Here, we aim at better understanding the hydroclimatic signal encoded in the leaf organic compounds of across the Atacama Desert's coastal mountain range (ca. 18–21°S). First, we investigate spatiotemporal patterns of fog occurrence and related moisture sources available for the plants applying a new satellite-based fog-detection approach. We then use stable carbon, oxygen and hydrogen (δC, δO, δD) isotope analysis of leaf wax -alkanes and cellulose to identify photosynthetic pathway as well as environmental and physiological processes that shape the isotopic composition in . We find that leaf wax -alkanes and cellulose reflect the balance of climatic and physiological drivers differently. While -alkane δD values more closely follow changes in precipitation δD, evaporative enrichment seems to have a dominant influence on cellulose δO values. Cellulose δD values are highly enriched compared to -alkane δD values, likely reflecting a predominant metabolic imprint on δD. δC signatures in the organic compounds are valid proxies for CAM activity. Our results prove the general applicability of the isotopic biomarkers for reconstructing environmental change in the coastal Atacama Desert. This approach can be extended globally to west-coast deserts that share fog as a major source of moisture.

中文翻译：

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评估阿塔卡马沙漠沿海依赖雾的铁兰叶子有机化合物的同位素组成：对干旱极限水文气候重建的影响

雾是智利北部和秘鲁南部沿海气候的重要组成部分。雾中的水分和养分维持着高度特有的植被（lomas）以及在海拔约 100 米处繁衍生息的独特生态系统。海拔 900–1200 米。尽管这种附生 CAM 凤梨科植物很好地适应了极端气候，但过去几十年观察到的种群数量下降对持续气候变化的长期生存提出了质疑。在这里，我们的目标是更好地了解阿塔卡马沙漠沿海山脉（约南纬 18-21°）叶子有机化合物中编码的水文气候信号。首先，我们采用新的基于卫星的雾检测方法，研究雾发生的时空模式以及植物可用的相关水分源。然后，我们使用叶蜡烷烃和纤维素的稳定碳、氧和氢（δ13C、δ18O、δD）同位素分析来识别光合作用途径以及形成同位素组成的环境和生理过程。我们发现叶蜡烷烃和纤维素以不同的方式反映了气候和生理驱动因素的平衡。虽然α-烷烃 δD 值更密切地跟随降水 δD 的变化，但蒸发富集似乎对纤维素 δO 值具有主导影响。与烷烃 δD 值相比，纤维素 δD 值高度富集，可能反映了 δD 的主要代谢印记。有机化合物中的 δ13C 特征是 CAM 活性的有效代表。我们的结果证明了同位素生物标记物在重建沿海阿塔卡马沙漠环境变化方面的普遍适用性。这种方法可以在全球范围内推广到以雾作为主要水分来源的西海岸沙漠。