Abstract Humans have been present in the Andes since about 12,000 calibrated years before present (cal yr BP), transitioning from hunter-gatherers to agropastoralist societies in the mid-Holocene. Yet, the timing and effects of this change in behavior on the ecosystem are largely unknown. Using titanium from XRF analysis, loss-on-ignition (LOI), fossil pollen, Sporormiella, and charcoal, we present a high-resolution 12,000-yr paleoecological history of Lake Llaviucu, a mid-elevation lake in the Ecuadorian Andes. For the entire period of study, humans were active in this landscape, with signs of agropastoralism being present since c. 6100 cal yr BP. Apparent ENSO activity, inferred from titanium inputs to the sediment is also heightened at c. 6100 cal yr BP. A trajectory of increasing landuse seems to have peaked in terms of maize production between c. 2900 and 800 cal yr BP. Thereafter, larger abundances of Sporormiella spores suggest that pastoralism was of increasing importance; a pattern disrupted by European arrival. Apparent peaks in El Nino Southern Oscillation (ENSO) appears to be linked to fire and maize frequency. We investigated the relationship between the Lake Llaviucu record and that of nearby Lake Pallcacocha, which is often cited as providing a regional ENSO history.

中文翻译：

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在安第斯山脉采用农牧业并增加 ENSO 频率

摘要 人类从大约 12,000 年前（cal yr BP）开始就出现在安第斯山脉，从狩猎采集者过渡到全新世中期的农牧社会。然而，这种行为变化对生态系统的时间和影响在很大程度上是未知的。使用来自 XRF 分析的钛、烧失量 (LOI)、化石​​花粉、孢子菌和木炭，我们展示了厄瓜多尔安第斯山脉中海拔湖泊 Llaviucu 湖 12,000 年的高分辨率古生态历史。在整个研究期间，人类活跃在这片土地上，自公元前 10 年以来就出现了农牧业的迹象。6100 卡年 BP。从钛输入到沉积物中推断出的表观 ENSO 活动也在 c 处升高。6100 卡年 BP。就 c 之间的玉米产量而言，土地利用增加的轨迹似乎已经达到顶峰。2900 和 800 cal yr BP。此后，大量的孢子菌孢子表明畜牧业变得越来越重要。一种被欧洲人的到来打乱的模式。厄尔尼诺南方涛动 (ENSO) 的明显峰值似乎与火灾和玉米频率有关。我们调查了 Llaviucu 湖记录与附近的 Pallcacocha 湖记录之间的关系，后者经常被引用为提供区域 ENSO 历史。