After the second World War, socio-economic developments and the spread of the chestnut blight meant that many of the heavily used chestnut orchards in southern Switzerland were left without any management. In the absence of cultural inputs, the anthropogenic origin of the stands became less apparent and their structures tended to disintegrate. A hierarchical approach was used to study the changes in stand characteristics over time. The species composition, structure and percent cover of the stands were studied at medium level using aerial photographs, with particular regard to medium term (35 years) changes. On a smaller scale, dendroecological methods were used to investigate the timing and ecology of the regeneration and growth of both invading and orchard trees. The results show clearly that the chestnut orchards were invaded by a large variety of species, which varied according to site conditions. These powerful natural dynamics are due to both the open structure of the chestnut orchards and the lack of resilience shown by the orchard-trees when suddenly submitted to natural competition. The main factors influencing the evolution of these stands are presented and discussed. A better understanding of these kinds of evolutionary processes is a prerequisite if future forest and landscape management is to be sustainable.