摘要：Arid and semi-arid lands in Mexico dominate 60% of the national territory. They harbor many endemic species, as well as a large proportion of the population, and offer diverse ecosystem services. These regions are subjected to anthropogenic impacts derived from agriculture and livestock farming, which have caused land degradation and desertification. In addition, these ecosystems are highly sensitive to climate variability and projected global environmental change. However, information about how land use/land cover change and climate variability processes overlap and synergize each other in these ecoregions is scattered in different publications, and it is desirable to integrate it to provides more complete information for decision making. In this study we describe both land cover and land use changes in the five arid and semi-arid ecoregions in Mexico (Sonoran, Chihuahuan, Tamaulipan, Mexican High Plateau and Tehuacán-Cuicatlán valley) between 2002 and 2011, and their current exposure to droughts, low temperatures, floods and tropical cyclones. These results are discussed in terms of regional climate trends documented in the literature. We found that land use and land cover change differ between ecoregions, with the Sonoran and Chihuahuan ecoregions being the least affected. The overall exposure to extreme climate events is high in all ecoregions except for the Tehuacán-Cuicatlán valley, although each region has different exposure profiles. Observed trends for all ecoregions generally point towards an increase in both maximum and minimum temperatures, while trends for precipitation are less clear. Our results can serve as a guideline for identifying areas where anthropogenic processes of land use and land cover changes and extremes climatic events synergize, to better guide management under a changing environment
