Socioeconomics explain tree diversity, abundance, and composition in the compact city of Barcelona, Spain

Trees are frequently unevenly distributed in urban areas, and their diversity, abundance, and composition vary spatially. Some studies have shown that the unequal distribution of urban trees can be associated with de-mographic and socioeconomic factors. However, most studies have been conducted in diffuse urban systems using remotely-sensed tree cover within single or aggregated land-use types. We examined if the relationship between tree diversity, abundance, composition, and socioeconomic factors varied across land-use types (parks, streets, zonal areas, and total) in the compact city of Barcelona, Spain. We calculated tree species richness and abundance across 73 neighborhoods using 229,962 geo-referenced records of individual trees sampled in 2021. Life expectancy positively explained tree richness and abundance across land-use types, reinforcing that access to urban green infrastructure promotes longer life spans. In contrast, income did not positively explain tree richness or abundance, indicating that tree distribution does not directly result in biodiversity and green space in-equalities for disadvantaged groups in terms of income. Total tree composition across neighborhoods responded to socioeconomic gradients, evidencing that neighborhood appearances are socially stratified. Street tree abundance increased in densely populated neighborhoods, possibly because intense street tree plantings in these neighborhoods compensate for the lack of other green infrastructure. Urban tree planting, particularly in streets, can be an effective strategy to increase green spaces in compact cities to overcome the disparities resulting from the unequal distribution of urban vegetation. Long-term data on socioeconomic factors and urban tree distri-bution are necessary to determine how social stratification affects urban diversity.