Urban vegetation cover correlates with environmental variables in a desert city: insights of mitigation measures to climate change

Green cover and air quality are important components of life quality and human ecology in arid lands. In the Sonoran Desert of Mexico, Hermosillo is the largest city with a population of 710,000. This city is currently affected by dust pollution and a large part of its population suffers respiratory diseases. Moreover, Hermosillo is considered highly vulnerable to climate change. The objective of this work was to correlate socio-economic variables such as population density and unpaved cover to total suspended particles (TSP), daily temperature oscillation (DTO), and vegetation cover (VC) to establish priority zones for reforestation for the city government. We divided Hermosillo in 440 sampling areas corresponding to Basic Geostatistics Urban Areas (AGEB) as defined by Instituto Nacional de Estadistica Geografia e Informatica (INEGI). We estimated TSP and DTO for each AGEB by spatial interpolation using the splines with barriers from 3 and 7 sampling stations, respectively. We obtained population density for each AGEB from the 2010 Population and Housing Census by INEGI and percentage of unpaved cover for each AGEB from municipal government records. We mapped VC analyzing digital aerial ortho-photos (resolution 15 x 15 cm per pixel) using GIS and manual digitization. We estimated VC at the AGEB level by sampling. Average VC percentage for Hermosillo is 6.4%. We also found that VC is negatively associated with TSP and DTO, highlighting the importance of further increasing green cover to enhance urban life quality in arid lands. Population density (PD) and unpaved cover (UC) were also positively correlated to DTO and marginally with TSP. Our research approach at a local scale, using an accessible methodology and inexpensive data inputs, can be easily applied to other arid cities around the world. We produced a map of prioritization reforestation zones for Hermosillo.