How does rural labor migration affect crop diversification for adapting to climate change in the Hehuang Valley, Tibetan Plateau?

Crop diversification has become a widely adopted adaptive strategy for farmers in developing countries to address the negative effects of climate change. However, with the development of secondary and tertiary industries in developing countries, an increasing number of agricultural laborers have migrated away from rural areas to seek off-farm employment, which reduces livelihood vulnerabilities and may hinder the adoption of crop diversification strategies. There is still a lack of case studies that address how labor migration affects crop diversification. To fill in this gap, we first propose a theoretical framework to address the impact of labor migration on crop diversification under the background of climate change; then, with the data collected from 499 households in the Hehuang Valley (HV), Tibetan Plateau, we explore the factors influencing crop diversification by employing Tobit model. The results show that: (1) crop diversification in the HV exhibits a downward trend due to climate change, with the crop diversification index dropping from 1.026 in 2009 to 0.884 in 2016. (2) Labor migration is obvious in the HV, and households without migrant laborers are more likely to adopt crop diversification strategies to combat climate change risks. (3) Household size, crop subsidies, crop income, and agricultural equipment inputs have significant positive effects on crop diversification, whereas farmers' perceptions of precipitation change, income of migrant laborers, workplace of migrant laborers and the average area of cultivated plots have significant negative effects. The findings of this study provide empirical evidence for understanding the impact of labor migration on crop diversification for adapting to climate change, and can help decision makers formulate effective measures to improve crop diversification by addressing key factors in priority, so as to ensure food security in the HV.