This thesis investigates the impact of rural to urban migration on long-standing commons regimes in the Sierra Norte (northern highlands) of Oaxaca – the most biologically and culturally diverse state in Mexico. Since the second half of the twentieth century, local communities have been engaged with regional, national and international markets for wage labour, with many losing a significant percentage of their resident populations. The study shows how demographic and cultural change is impacting the two social institutions – cargos and tequios – that underpin the highly autonomous form of governance the region is famed for. The loss of able-bodied men and women has meant that these customary systems are struggling to remain operational. In response, a number of far-reaching changes have been introduced, including institutional adaptations and the forging of strong translocal ties that show potential for reducing the vulnerability of affected communities. However, while migration was temporary or circular for much of the 1970s, 1980s and 1990s, thus helping to maintain a balance between subsistence production and market engagement, a form of semi-permanent or permanent migration has come to dominate over the past decade and a half. This critical yet poorly recognised shift in migration dynamics has seen new and increased pressures emerge, and served to reduce the effectiveness of adaptive strategies at the community level. Within this context, the implications for commons theory are discussed, with two alternate frameworks (rational choice vs. moral economy) utilised to explain why institutions may persist, transform or fail in the face of change. In addition, a layer of complexity is added to the body of work examining the consequences of rural depopulation on Mexican forest landscapes and associated biological diversity. The study questions the assumption that rural to urban migration necessarily stimulates ecosystem recovery and enhances biodiversity conservation at a landscape scale. In fact, because of abandonment of a mosaic of use, the net effect may be an overall loss of biodiversity. From a policy perspective, the principal contributions of the study are especially pertinent at a time when funding agencies and government programs show belated interest in the consequences of out-migration for environmental management, resource use and rural livelihoods in tropical country settings.

This thesis investigates the impact of rural to urban migration on long-standing commons regimes in the Sierra Norte (northern highlands) of Oaxaca – the most biologically and culturally diverse state in Mexico. Since the second half of the twentieth century, local communities have been engaged with regional, national and international markets for wage labour, with many losing a significant percentage of their resident populations. The study shows how demographic and cultural change is impacting the two social institutions – cargos and tequios – that underpin the highly autonomous form of governance the region is famed for. The loss of able-bodied men and women has meant that these customary systems are struggling to remain operational. In response, a number of far-reaching changes have been introduced, including institutional adaptations and the forging of strong translocal ties that show potential for reducing the vulnerability of affected communities. However, while migration was temporary or circular for much of the 1970s, 1980s and 1990s, thus helping to maintain a balance between subsistence production and market engagement, a form of semi-permanent or permanent migration has come to dominate over the past decade and a half. This critical yet poorly recognised shift in migration dynamics has seen new and increased pressures emerge, and served to reduce the effectiveness of adaptive strategies at the community level. Within this context, the implications for commons theory are discussed, with two alternate frameworks (rational choice vs. moral economy) utilised to explain why institutions may persist, transform or fail in the face of change. In addition, a layer of complexity is added to the body of work examining the consequences of rural depopulation on Mexican forest landscapes and associated biological diversity. The study questions the assumption that rural to urban migration necessarily stimulates ecosystem recovery and enhances biodiversity conservation at a landscape scale. In fact, because of abandonment of a mosaic of use, the net effect may be an overall loss of biodiversity. From a policy perspective, the principal contributions of the study are especially pertinent at a time when funding agencies and government programs show belated interest in the consequences of out-migration for environmental management, resource use and rural livelihoods in tropical country settings.