Urban forest biodiversity and cardiovascular disease: Potential health benefits from California’s street trees

Fig 4. Change in Shannon index by number of genera targeted for simulated LA planting. Figure Notes: Data for 61 zip codes that are at least partly within the boundaries of the city of Los Angeles, California, and are in the bottom 50th percentile in terms of total trees. The simulation evenly splits a total of 50 newly planted trees per zip code under five scenarios, each corresponding to a box plot: A single genus (the most common in LA, “top” and the fifth most common), as well as evenly splitting plantings across two, five, and ten genera. For example, in the top five genera scenario, each genus would increase the total trees by 50/ 5 = 10 trees. The Shannon Diversity Index is recalculated for each scenario and boxplots show the distribution in the change in the Shannon across 61 zip codes. https://doi.org/10.1371/journal.pone.0254973.g004 Table 4. Avoided mortality benefits for Los Angeles tree planting initiative. Scenario Shannon Heart Disease Rate Heart Disease Benefits Stroke Rate Stroke Benefits Total Benefits, Lo Total Benefits, Hi Top -0.39 14 -$742 4.9 -$266 $892 $1,792 Fifth -0.30 9 -$486 3.2 -$174 $1,240 $2,140 Top 2 0.054 -1.6 $89 -0.59 $32 $2,021 $2,921 Top 5 0.64 -22 $1,183 -7.9 $425 $3,508 $4,408 Top 10 1.1 -38 $2,041 -14 $733 $4,674 $5,574 Notes: Simulation of change in Shannon index and change in Heart Disease and Stroke Mortality Rates under five scenarios for 61 zip codes below the median number

of trees per zip code in the city of Los Angeles. Simulation assumptions: Plant 50 trees per zip code and either target the most popular tree genus in the city of Los Angeles in our data or the fifth most popular, or split the fifty trees across the top two, five, or ten genera (so 25, 10, or five trees per genera). For each scenario, calculate the new Shannon Index, then the implied change in the Shannon Index from the no planting data. Use the coefficients from Table 2 for Heart Disease -33.54, and Stroke, -12.04, to estimate the change in the mortality rate for each planting scenario. Benefits are calculated by multiplying the change in the mortality rate by the value of a statistical life of $5.6 million. https://doi.org/10.1371/journal.pone.0254973.t004 PLOS ONE Biodiversity and cardiovascular disease PLOS ONE | https://doi.org/10.1371/journal.pone.0254973 November 3, 2021 15 / 23