Resumen
Crop species diversity is a key component of agroecosystem resilience, food system stability, ecosystem services production, and sustainable development. Despite its importance, quantitative understanding of crop species diversity is often lacking. This study assesses changes in crop species production diversity in Mexico from 1980 to 2020 at state, regional, and national levels. Measures of crop species richness and effective diversity (alpha, beta, gamma) were derived from government production data on 304 species, each stratified into rainfed and irrigated components. Time series of these components reveal three main findings: (1) diversity generally increased during the study period, especially among fruits, vegetables, spices and herbs, and ornamental crops; (2) the diversity of irrigated crops was about two times higher than the diversity of rainfed crops, despite comprising a small fraction of the total cultivated area; and (3) the diversity of irrigated crops increased dramatically after implementation of the North American Free Trade Agreement (NAFTA) in 1994?though most increases occurred in dry northern regions where production depended on unsustainable irrigation. In sum, findings show that while crop diversity can contribute to numerous forms of sustainability, not all diversification processes derive from agroecologically-based, sustainable forms of intensification. In Mexico, crop species diversification was associated with a post-1994 boom in produce exports to the United States and the unsustainable use of scarce water resources at home. Such context-specific understanding is crucial for determining whether crop diversification, in all its forms, ultimately leads to sustainable outcomes.