Equity impacts of street tree spacing guidelines: A case study in two Los Angeles neighborhoods

Growing interest in green infrastructure to improve urban life and address the challenges of climate change is often channeled, at the level of municipal government, into programs to plant street trees. Existing disparities in urban tree canopy are well documented, yet the street tree spacing guidelines which dictate where trees can be located relative to other infrastructure in the right-of-way, which serve to severely limit the possibilities for adding future trees, receive little attention. We present a case study of a low- and high-income neighborhood in Los Angeles, modeling two policy scenarios, and find that structural differences between the two neighborhoods (e.g., parcel size, intersection density, and street width) differentially limit the number of trees which could be planted in each neighborhood, suggesting that existing guidelines may be a barrier to achieving municipal equity goals. Less restrictive guidelines were found to minimize between-neighborhood differences in tree quantity, yet substantial disparities remained in tree stature, a proxy for tree canopy, suggesting that shade equity may be more difficult to address with guideline changes alone.