The mid-elevation settings of the Andes are important biodiversity hotspots, yet little is known of their long-term ecology or environmental change. Here, we assess 30,000 years of landscape and vegetation dynamics on an alluvial terrace located in a mid-elevation valley of the Ecuadorian Andes (Campo Libre). We used loss-on-ignition and particle size analysis to reconstruct past river dynamics, charcoal analysis to reconstruct past fire regimes, and phytolith analysis to reconstruct vegetation change through time. Our results show that Campo Libre was a part of the active floodplain system of the Quijos River until 18,000 cal yr BP. The biggest vegetation change in vegetation at Campo Libre occurred ca. 13,000 cal yr BP, when the site warmed and dried, transforming the swampy alluvial terrace into a palm forest. As Holocene precipitation increased, the site transformed back into a swamp around 7500 cal yr BP, and it remained that way until maize agriculture began around 4600 cal yr BP. Local and regional fires were absent from the system until regional fires were detected ca. 3300 cal yr BP. By ca. 2700 cal yr BP, maize cultivation became frequent and regular. Climate, tectonic activity, and the human history have shaped the modern vegetation around Campo Libre, although during different periods of the Holocene. Our results demonstrate the ability of phytoliths to reconstruct vegetation change through time, and show that the mid-elevation Andean valley systems were highly dynamic over the last 30,000 years.

安第斯山脉中部海拔地区是重要的生物多样性热点，但对其长期的生态或环境变化知之甚少。在这里，我们评估了位于厄瓜多尔安第斯山脉中部高海拔山谷（Campo Libre）的冲积阶地上30,000年的景观和植被动态。我们使用了点火损失和粒度分析来重建过去的河流动力学，使用木炭分析来重建过去的火灾状况，并使用了硅藻土分析来重建随时间变化的植被。我们的结果表明，Campo Libre一直是基霍斯河活跃洪泛区系统的一部分，直到BP年18,000 cal BP。Campo Libre植被的最大植被变化发生在大约 BP 13,000 cal yr，该地点变暖和干燥后，将沼泽冲积层变成了一片棕榈树林。随着全新世降水的增加，该地点转变为大约7500 cal BP BP的沼泽地，并且一直保持这种状态，直到玉米农业在4600 cal BP左右开始。该系统不存在局部和区域起火，直到在大约20分钟内检测到区域起火为止。BP 3300 yr年。大约 每年2700 cal BP，玉米种植变得频繁而有规律。气候，构造活动和人类历史塑造了坎波里伯周围的现代植被，尽管处于全新世的不同时期。我们的研究结果表明了硅藻土重建植被随时间变化的能力，并表明中海拔的安第斯谷地系统在过去的30,000年中具有很高的动态性。该系统不存在局部和区域起火，直到大约在大约30分钟内检测到区域起火。BP 3300 yr yr。大约 每年2700 cal BP，玉米种植变得频繁而有规律。气候，构造活动和人类历史塑造了坎波里伯周围的现代植被，尽管处于全新世的不同时期。我们的研究结果表明了硅藻土重建植被随时间变化的能力，并表明中海拔的安第斯谷地系统在过去的30,000年中具有很高的动态性。该系统不存在局部和区域起火，直到在大约20分钟内检测到区域起火为止。BP 3300 yr yr。大约 每年2700 cal BP，玉米种植变得频繁而有规律。气候，构造活动和人类历史塑造了坎波里伯周围的现代植被，尽管处于全新世的不同时期。我们的研究结果表明了硅藻土重建植被随时间变化的能力，并表明中海拔的安第斯谷地系统在过去的30,000年中具有很高的动态性。