Land use during the colonial period in Lago Vichuquén was characterized by agriculture, cattle ranching, and mining under the Encomienda (feudal) system (Vidal and Ramírez 1985). Historical documents show that before 1580 CE, the Vichuquén watershed was occupied by Indigenous communities dedicated to small-scale farming, extracting wood, and mining activities. The sediment δ15Nom values from this period covary with TN, indicating pulses of enhanced N input from the watershed were likely linked to an increase in land use and sediment input (indicated by changes in magnetic susceptibility and Ti content in Fig. 2).

From the onset of the 19th to the mid-20th centuries, δ15Nom and TN values decreased slightly, most likely related to lowered sediment input from the watershed until the second half of the 19th century. In contrast, the last part of the 20th century witnessed