Background: Mountain environments are fragile socio-ecological systems and the conservation of their biological and cultural diversities- seen as co-evolving, strongly intertwined entities-represents a crucial issue for fostering their sustainability. Very few ethnobiological studies have assessed in the mountainous regions of Europe how local botanical knowledge, which represents a vital portion of the local environmental knowledge (LEK), changes over time, although this may be quintessential for a better understanding of the factors influencing how knowledge and practices are shaped, eroded, or even re-created.

Methods: In the current study, we compared the gathering and use of local medicinal plants in the Upper Sangone Valley, Western Italian Alps, Piedmont (NW Italy) as described in a field study conducted in the mid-seventies and published in 1977 and those arising from field research that we conducted in the spring of 2015 and 2018, during which time ethnobotanical and ethnomycological information concerning both folk medicinal and wild food uses was obtained via 47 in-depth open and semi-structured interviews with community members.

Results: In total, one hundred thirty folk taxa represent the past and present medicinal and wild food plant/mushroom heritage of the Sangone Valley: 26 herbal taxa were recorded 40 years ago only; 68 herbal and wild food taxa have been recorded in the current study only; and 36 herbal taxa have been continuously used during the last 40 years. There were no remarkable quantitative differences between the two diachronic medico-ethnobotanical datasets, but the qualitative differences were substantial. The gathering and use of some medicinal plants growing in meadows, forests and higher mountain environments (i.e. Arctostaphylos, Filipendula, Hepatica, Larix, Laserptium, Picea, Polygonatum, Primula, Tussilago and Veronica spp.) disappeared, whereas the collection of plant genera growing in more anthropogenic environments or possibly promoted via popular books and media has been newly introduced (i.e. Aloysia, Apium, Brassica, Crataegus, Epilobium, Fumaria, Geranium, Juniperus, Melissa, Rubus, Rumex, Sedum, Silybum, Taraxacum and Vaccinium spp.).

Conclusion: The findings show a renegotiation of the situativity that for centuries forged the embeddedness of local communities in their natural environments, probably heavily informed in the past by prevalent pastoralist and forest-centred activities and thus by a deeper knowledge of higher mountain and forest environments. The re-arrangement of a more domestic and more "globalized" herbal knowledge system was possibly inspired by new urban residents, who started to populate the valley at the end of the Seventies, when the original inhabitants abandoned their homes for the urban centres of the Piedmontese plain. The current study suggests that future directions of ethnobiological research should more carefully look at the adaptive capacity of LEK systems.