Mountain lakes are integrated sentinels of changes in the terrestrial environment, where these changes threaten the quality of the ecosystem services these lakes provide, including high biodiversity, economic and leisure activities. Few evidentiary records exist of the long-term relationships between human pressure and observed impacts. Multiproxy analyses of the Lake Bénit sediment sequence, including dating, grain-size, geochemistry, pollen, non-pollen palynomorphs and chironomid assemblage reconstructions, allowed reconstruction of past environmental evolution and lake trophic changes. Combined with soil analyses of the catchment, these data provide a record of the relationships between human activities and the lake-catchment ecosystem, and show the effect of inundation of the shore previously used as pasture. From 2100 to 1100 yrs cal. BP, the catchment was forested. During the Middle Ages, grazing deforested the catchment, triggering an increase in erosion and a change in sediment sources. The lake remained oligotrophic over most of the last millennia. The trophic state changed abruptly in the 20th century with intensification and multiplication of tourist activities in the catchment, i.e., fishing, hiking, while pastoral activities decreased. The sudden eutrophication coincides with an artificial increase of the lake water level in AD 1964 to improve fishing activities. A release of phosphorus (P) from the flooded soils was observed, which may be responsible for the current eutrophication. One thousand years of grazing practices would have led to the observed P concentrations in the soils of the lake shore, transferred by the cattle to this area. Our study highlights the combined effects of past and recent activities on the current eutrophication process, and the legacy of both soils and early anthropogenic activities.

高山湖泊是陆地环境变化的综合标志，这些变化威胁着这些湖泊提供的生态系统服务的质量，包括高生物多样性，经济和休闲活动。很少有证据记录人类压力与观察到的影响之间的长期关系。贝尼特湖沉积物序列的多代理分析，包括年代测定，粒度，地球化学，花粉，非花粉状单孢粉和奇异虫组合重建，可以重建过去的环境演变和湖泊的营养变化。结合流域的土壤分析，这些数据提供了人类活动与湖泊流域生态系统之间关系的记录，并显示了以前用作牧场的海岸被淹没的影响。从2100年到1100年 BP 集水区被森林覆盖。在中世纪，放牧使流域森林砍伐，引发了侵蚀加剧和沉积物来源变化。在过去的几千年的大部分时间里，该湖一直是贫营养的。在20世纪，由于集水区旅游活动的激增和繁衍，营养状态急剧变化，即钓鱼，远足，而牧民活动减少。突然的富营养化与公元1964年人为增加湖泊水位以改善捕鱼活动相吻合。观察到从淹没土壤中释放了磷（P），这可能是当前富营养化的原因。一千多年的放牧习惯已经导致了在湖岸土壤中观察到的磷浓度，这些浓度是由牛转移到该地区的。我们的研究强调了过去和最近的活动对当前富营养化过程的综合影响，以及土壤和早期人类活动的遗产。