The anatomy of the Last Glacial Termination (T1) in the southern mid-latitudes, and its relationship with changes in the Southern Westerly Winds (SWW), offers empirical constraints for understanding the mechanisms involved in the transition from the Last Glacial Maximum into the current interglacial. Northwestern Patagonia (40°-44°S) is a sensitive region for monitoring past changes in the SWW, the Patagonian Ice Sheet, terrestrial ecosystems, and fire regimes through T1. Here we present results from Lago Fonk (∼40°S) to examine the structure of T1 based on the palynological, macroscopic charcoal, elemental, and isotopic composition of organic lake sediments.

We observe an instantaneous establishment of Nothofagus-dominated forests at the onset of T1, followed by a diversification and densification trend that culminated with the establishment of thermophilous, Myrtaceae-dominated North Patagonian rainforests between ∼15.6–14.7 cal ka BP. The expansion of the conifer Podocarpus nubigena marks a shift to cool-temperate and hyperhumid conditions, coeval with high lake levels and enhanced algal productivity between ∼14.7–11.9 cal ka BP. Stand-replacing fires, driven by enhanced seasonality or high-frequency rainfall variability, started at ∼12.4 cal ka BP and catalyzed the rapid spread of Weinmannia trichosperma. Subsequent warming and a decline in precipitation at ∼11.4 cal ka BP led to intense fire activity, lake-level lowering, and establishment of the Valdivian rainforest trees Eucryphia/Caldcluvia. Our results suggest a coherent linkage between changes documented in the amphi south Pacific region and Antarctic ice cores during T1. This implies a zonal and hemispheric response to changes in the position/intensity of the SWW that emphasizes their central role as a key driver of the hemispheric and global climate evolution through T1.

中纬度南部末次冰期终结 (T1) 的解剖结构及其与南部西风 (SWW) 变化的关系，为理解从末次冰期最大值过渡到当前的机制提供了经验限制。间冰期。巴塔哥尼亚西北部 (40°-44°S) 是通过 T1 监测 SWW、巴塔哥尼亚冰盖、陆地生态系统和火灾状况过去变化的敏感区域。在这里，我们展示了来自 Lago Fonk (∼40°S) 的结果，以根据有机湖泊沉积物的孢粉学、宏观木炭、元素和同位素组成来检查 T1 的结构。

我们观察到在 T1 开始时立即建立了以Nothofagus为主的森林，然后是多样化和致密化趋势，最终在 ~15.6-14.7 cal ka BP 之间建立了嗜热、桃金娘科为主的北巴塔哥尼亚雨林。针叶树Podocarpus nubigena的扩张标志着向冷温带和高湿条件的转变，同时伴随着高湖水位和 14.7-11.9 cal ka BP 之间的藻类生产力提高。受季节性增强或高频降雨变异性驱动的替代火灾始于~12.4 cal ka BP 并催化了Weinmannia trichosperma的快速传播. 随后的变暖和约 11.4 cal ka BP 的降水减少导致强烈的火灾活动、湖泊水位降低以及 Valdivian 雨林树木Eucryphia/Caldcluvia 的建立。我们的结果表明，T1 期间两栖类南太平洋地区和南极冰芯中记录的变化之间存在连贯的联系。这意味着纬向和半球对 SWW 位置/强度变化的响应强调了它们作为通过 T1 的半球和全球气候演变的关键驱动因素的核心作用。