Stable oxygen isotopes records (δO) in tree-rings are commonly used to assess the response of trees to environmental variability being a valuable tool for studying past climate at different temporal and spatial scales. This is particularly relevant in semi-arid regions like the southern Tropical Andes, where ongoing environmental changes coincide with a rapidly increasing demand for hydrological resources, presenting a challenge for ecosystem dynamics and water resource management. In this study, we aim to determine the main spatio-temporal variability of a new network of δO chronologies during the last century, and their relationships with hydroclimate and tropical circulation at local to subcontinental scales throughout the Tropical Andes. For this purpose, we develop six δO tree-ring chronologies across a 450 km latitudinal moisture gradient in the southern Tropical Andes adjacent to the Atacama Desert, covering the period 1900–2007. Results show a clear latitudinal gradient in the δO values across the network and significant relationships are observed with other δO tree-ring chronologies in Tropical South America, demonstrating clear regional climate influences at a subcontinental scale. A principal component analysis of the δO tree-ring chronologies demonstrate a strong regional environmental signal contained in the network, exhibiting a main temporal pattern (PC1 δO) that explains 63% of the total variance during the period 1900–2007. Comparisons between PC1 δO and environmental variables showed significant negative relationships with precipitation and soil moisture, and positive relationships with temperature and vapor pressure deficit (VPD) during summer when the South American monsoon occurs. The main δO tree-ring network signal clearly records tropical atmospheric and circulation patterns across South America. The easterly wind flux conditions from the Amazon basin favor lower δO values, and the PC1 δO exhibit significant positive correlations with VPD across the entire Tropical Andes and the northern portion of the Amazon basin, and as well as outgoing longwave radiation across the southern Tropical Andes and part of the Amazon basin. The close relationships between the regional signals from our δO tree-ring network with the previously mentioned parameters, highlight the potential to develop future hydroclimatic-related reconstructions with these δO records to assess climate variability and change across the Tropical Andes.

中文翻译：

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由新的 Polylepis tarapacana 树轮网络的 δ18O 同位素记录的热带安第斯山脉的水文气候变化


树木年轮中的稳定氧同位素记录 (δ18O) 通常用于评估树木对环境变化的响应，是研究不同时空尺度过去气候的宝贵工具。这对于热带安第斯山脉南部等半干旱地区尤其重要，这些地区持续的环境变化与对水文资源的需求迅速增加同时发生，对生态系统动态和水资源管理提出了挑战。在这项研究中，我们的目标是确定上个世纪新的 δ18O 年代学网络的主要时空变化，及其与整个热带安第斯山脉局部到次大陆尺度的水文气候和热带环流的关系。为此，我们在毗邻阿塔卡马沙漠的热带安第斯山脉南部地区 450 公里的纬度湿度梯度上开发了 6 个 δ18O 树木年表，涵盖 1900 年至 2007 年期间。结果显示，整个网络的 δ18O 值存在明显的纬度梯度，并且与热带南美洲的其他 δ18O 树轮年表观察到显着关系，证明了次大陆尺度上明显的区域气候影响。 δ18O树轮年表的主成分分析表明网络中包含强烈的区域环境信号，表现出主要时间模式（PC1δ18O），解释了1900-2007年期间总方差的63％。 PC1 δ18O与环境变量的比较表明，在南美季风发生的夏季，PC1 δ18O与降水量和土壤湿度呈显着负相关，而与温度和蒸气压赤字（VPD）呈正相关。 主要的 δ18O 树轮网络信号清楚地记录了整个南美洲的热带大气和环流模式。来自亚马逊盆地的东风通量条件有利于较低的 δ18O 值，PC1 δ18O 与整个热带安第斯山脉和亚马逊盆地北部的 VPD 以及整个热带安第斯山脉南部的出射长波辐射呈显着正相关以及亚马逊盆地的一部分。我们的 δ18O 树木年轮网络的区域信号与前面提到的参数之间的密切关系，凸显了利用这些 δ18O 记录进行未来水文气候相关重建以评估整个热带安第斯山脉气候变率和变化的潜力。