Yard-Scale Socioeconomic and Ecological Factors Shape Urban Forest Structure, Diversity, Soils, and Ecosystem Services

Urban ecology studies have demonstrated that residential vegetation differs across neighborhoods, socioeconomic gradients, housing age, and parcel configuration. But such coarser scale studies often overlook parcel and yard-scale land tenure, individual land and homeowner actions, and within-yard heterogeneity. Thus, we studied how yard location and socio-ecological factors influence urban forest structure, woody plant diversity, and ecosystem service potential in private, residential yards in Los Angeles, California (US). Overall, 2,303 individuals and 325 shrub, 95 tree, and 7 palm taxa were measured across different yard locations (n = 35 yards). Tree crown volume increased with species richness, tree density, and diversity. Older neighborhoods were characterized by higher tree and shrub frequency; newer ones had higher palm frequencies. Tree frequency (12.3%), mean species richness (45.8 ± 21.8) and mean crown widths (2.1 ± 2.4 m) were greatest in front yards. Cultural ecosystem services were most common in back yards; regulating and provisioning ecosystem services were most common in front yards. Tree shade potential was primarily driven by soil quality, tree size, and crown architecture. Urban forest structure, condition, and tree distance to building metrics and results also have implications for assessing potential wildfire hazards. Finally, affluence and education were positively related to tree shade potential while housing age, owner-occupied, and areas with white populations exhibited a negative relationship. Our parcel-level – and yard location- approach and findings show how soils, woody plant diversity, and urban forest structure metrics influence shade potential and woody plant diversity across yard location and socio-economic gradients.