Local Ecological Knowledge (LEK) is fast disappearing globally but the drivers of this loss are not fully understood. We present a a case study of how even long-standing and regulated forms of LEK are vulnerable to erosion as market forces spread to regions which have historically been peripheral to global markets.We consider changes in knowledge and use of a cultural keystone species, totora, in the Altiplano of Bolivia and Peru around Lake Titicaca. Totora has been used for a variety of purposes and historically its cultivation and planting was regulated by village co-operative councils, called ayllus . We argue that a significant decline in the use of totora in the Altiplano along with the disappearance of the regulatory power of ayllus have primarily been driven by the integration of the Altiplano into the global market system, which has led to the replacement of totora with industrially manufactured goods, such as plastics and concrete. It has also undermined social bonds as individuals rather than the ayllu become the fundamental agents of economic decision-making.