Drivers of urban biodiversity in Mexico and joint risks from future urban expansion, climate change, and urban heat island effect

biodiversity at finer scales in large urban conglomerates (e.g., in the central Valley of Mexico). Although GDP showed a null effect in RF models after control by area in species richness, fine-scale wealth and socioeconomic data probably have more explanatory power than GDP at the municipality level. There is a well-established relationship between local biodiversity and economic wealth for multiple taxa [77–79], and therefore, a similar pattern may be discovered in future studies with more appropriate economic and wealth variables. Similarly, the negative effect of the percentage of people working in the primary sector (porPob; Fig 2) suggests that municipalities with high social marginalization likely have fewer green spaces and fewer species. The lack of importance of other variables is likely due to the coarse-grain scale of the avail- able data (Table 1). We believe that finer-grain data, including microclimatic variation, size of urban green spaces (e.g., small-intermediate green spaces with less than 1 ha), landscape con- nectivity, local vegetation diversity, and socioeconomic and wealth indicators at the AGEB scale, help us to understand better what drives urban biodiversity in Mexican municipalities. In addition, data about the historical trajectories of Mexican cities (e.g., past urban dynamics and ages) would allow us to evaluate whether urban biodiversity followed similar courses as in Europe [7]. Further research on local biotic inventories is necessary to understand the local processes

driving urban species richness. The interplay of different scale-dependent processes shapes urban ecological patterns, and more work on this is required to answer questions oriented to establish how species respond to local urban environments. Further extensive city-scale field- work, ideally across urban-rural gradients, could help elucidate how current urban biodiversity can be maintained or improved and their emergent ecosystem services upon specific urban green space configurations. Multivariate risk index Our results show that increasing temperatures produced by the urban heat island and urban expansion could impact urban biodiversity and exacerbate climate change impacts at local scales. Municipalities in northern Mexico should be considered as a priority for local mitigation and habitat recovery due to high exposure to future climate change, urban sprawl, and the urban heat island. These municipalities have faced stronger temperature increases due to con- temporary climate change than other regions [80]. However, we consider that it is necessary to conduct a comprehensive assessment of how urbanization affects local biodiversity across spatial scales in these cities, which are projected to grow quickly in the next decades. National studies, as we conduct here, allow us to identify the main trends of land-use change and critical resource areas; however, more detailed local-scale studies are needed for effective monitoring programs and developing local conservation strategies to avoid further biodiversity loss. For instance, the

identification of specific threats for species and populations in each city through long-term monitoring schemes is the first step to ensure these conservation goals in the medium and long- term. The local governments can boost campaigns of citizen science to increase awareness and collect biodiversity data to improve local species checklists and field-based population studies of targeted taxa. In addition, further studies may assess how species’ traits respond to urbanization and climate change at the local scales [81, 82]. These studies are necessary to evaluate how differ- ent taxa populations respond to the ongoing urban heat island effects. Another element that needs to be assessed how urban protected areas are working across gradients of urbanization [83], climate change, and UHI. In particular, it is necessary to con- duct studies to establish the effectiveness of these conservation areas inside cities and how they can improve in the face of future climate change and other human stressors. Local PLOS ONE Urban biodiversity and anthropogenic pressures PLOS ONE | https://doi.org/10.1371/journal.pone.0308522 October 4, 2024 13 / 19