Urban forest biotope mapping: A new approach for sustainable forest management planning in Mexico City

Abstract

Environmental demands for greener, more sustainable urban areas are increasing worldwide and are particularly magnified in megacities such as Mexico City, the largest city in North America. Strategic land use planning initiatives aimed at integrated and sustainable urban green infrastructure across broader city landscapes require an understanding of urban environments, their urban forest, and their spatial distribution. However, this approach has not been widely used in megacities. Here, we use the urban biotope approach to address the knowledge gap and help inform land-use planning to support greater urban forest sustainability in Mexico City. Two levels of biotope classes, broader-level (3 classes defined by canopy cover) and finer-level (7 classes describing urban forest characteristics), were modeled and mapped across the city. Statistical modeling was done using a random forest algorithm, a set of uncorrelated predictor variables, and field observations to predict biotope presence. Models of the broader-level biotopes yielded better prediction results (AUC > 0.90) than the finer-level biotopes (AUC values from 0.61 to 0.88). Classification errors ranged from 6.5 to 100 %, indicating different levels of predictive confidence. Of all mapping units of the broader-level biotopes 87 % were predicted while of the finer-level biotopes only 12.7 %. As the finer-level predictions often overlap, more field data and better predictors are required to accurately capture biotope classes. The modeled biotopes can inform urban planning across spatial scales, from the neighborhood and borough level to the city-wide scale, and across the residential-commercial land use, which requires more greening efforts. Results suggest that more field and spatial data, and a smaller grain size, can improve biotope models and maps to better represent the variation in urban forest characteristics across Mexico City. Biotope maps are a practical tool to guide spatial planning, identify priority areas for canopy protection and tree planting, and set tree diversification goals.