Southern California and Southern Australia are two regions of the world which share many climatic, socioeconomic and demographic characteristics that lend themselves to meaningful exchanges of knowledge and innovations. With the benefit of Australia’s documented experiences, California can learn what solutions worked and did not work in Australia, potentially avoiding major pitfalls. While some changes in California are already underway, many opportunities – and challenges – still remain. California’s policymakers and residents can adopt and adapt the most fitting solutions from Australia’s experience. California, and especially Southern California, can use these to appropriately and effectively respond to the extremes of our long-term water and climate crises. In doing so, we will put California on a better path towards resilience as we navigate the challenges of drought, flood and extreme heat forecast to increase in our future. In October 2014, TreePeople and The Energy Coalition co-organized and co-led a delegation of policymakers and elected officials from throughout California to the Australian cities of Melbourne and Adelaide. These cities implemented innovative water management solutions during the Millennium Drought that helped to drought-proof their water supplies and increase resilience in anticipation of a changing climate. The goals of this delegation were to show California water leaders first-hand the drought and climate response initiatives that Adelaide and Melbourne employed and to focus on transferring and implementing viable approaches in California. This article highlights the key lessons learned from this research and provides recommendations for how Southern California can best approach transferring these lessons.

The Urban Forest Equity Collective (UFEC) is a consortium of forestry experts, Los Angeles (LA) City staff, community-based organizations, researchers, and consultants aiming to create holistic strategies to advance urban forest equity in the lowest-canopied neighborhoods. By conducting a holistic analysis and creating strategies to advance urban forest equity in LA, UFEC presents methods to address decades of systemic disinvestment and planning decisions that have resulted in poor public health outcomes, limited access to green spaces, and a host of related consequences ranging from heat exposure and poor air quality, to food insecurity and reduced ecosystem services.

Tree-planting municipalities and organizations face multiple challenges to achieving thriving urban forests, among which is providing establishment-period care to young trees. In arid and semi-arid regions in particular, delivering water to trees is a resource- and time-intensive activity often not covered by funding specified for tree planting. This study sought to address the need for establishment-period care by producing a replicable approach to engaging residents in environmental justice communities to actively care for young street trees planted in front of their homes. Using community-based social marketing in the community of Huntington Park (Los Angeles County, California, U.S.), researchers investigated socioeconomic and cultural characteristics to barriers and motivators regarding tree stewardship (i.e., watering, mulching, and weeding) and developed an outreach program strategy accordingly. The program was pilot-tested and evaluated for effectiveness in changing behaviors. Active, in-person outreach (doorto- door engagement with residents using program materials and demonstrating tree care actions) was tested against passive outreach (program materials were left at the doorstep); both were compared to baseline conditions. Evaluation of soil moisture, tree health, and presence of mulch was conducted over a six-week period after program outreach. Trees at homes in the active outreach group had significantly higher soil moisture, more mulch, and better observed health than trees at homes in the passive outreach group. Both groups had better outcomes as compared to pre-outreach baseline conditions. Results indicate that tree planting programs with limited resources for maintenance may find success in fostering tree stewardship among residents through active engagement.

Extreme heat in the United States is a leading cause of weather-related deaths, disproportionately affecting low-income communities of color who tend to live in substandard housing with limited indoor cooling and fewer trees. Trees in cities have been documented to improve public health in many ways and provide climate regulating ecosystem services via shading, absorbing, and transpiring heat, measurably reducing heat-related illnesses and deaths. Advancing “urban forest equity” by planting trees in marginalized neighborhoods is acknowledged as a climate health equity strategy. But information is lacking about the efficacy of tree planting programs in advancing urban forest equity and public wellbeing. There is a need for frameworks to address the mismatch between policy goals, governance, resources, and community desires on how to green marginalized neighborhoods for public health improvement—especially in water-scarce environments. Prior studies have used environmental management-based approaches to evaluate planting programs, but few have focused on equity and health outcomes. We adapted a theory-based, multi-dimensional socio-ecological systems (SES) framework regularly used in the public health field to evaluate the Tree Ambassador, orPromotor Forestal, program in Los Angeles, US. The program is modeled after the community health worker model—where frontline health workers are trusted community members. It aims to address urban forest equity and wellbeing by training, supporting, and compensating residents to organize their communities. We use focus groups, surveys, and ethnographic methods to develop our SES model of community-based tree stewardship. The model elucidates how interacting dimensions—from individual to society level—drive urban forest equity and related public health outcomes. We then present an alternative framework, adding temporal and spatial factors to these dimensions. Evaluation results and our SES model highlight drivers aiding or hindering program trainees in organizing communities, including access to properties, perceptions about irrigation responsibilities, and lack of trust in local government. We also find that as trainee experience increases, measures including self- and collective efficacy and trust in their neighbors increase. Findings can inform urban forestry policy, planning, and management actions at the government and non-profit levels that aim to increase tree cover and reduce heat exposure in marginalized communities.

Heat exposure poses health risks that disproportionately burden disadvantaged communities. Trees protect against heat, but significant barriers exist to growing robust urban forests. In drier climates, complex logistics of watering during a multi-year establishment period pose a challenge because street trees are typically unirrigated and funding for maintenance is generally unavailable. This study tested the impacts of varying theory-guided community engagement approaches on beliefs, attitudes, knowledge, and behaviors related to foster street tree stewardship and individual-level heat mitigation actions in 116 households in Los Angeles County, USA. We tested a control intervention against experimental messaging focused on either public health or environmental health, and also segmented participants by the degree of prior household engagement with a local tree planting group. Outcomes measured were soil moisture, tree health, and survey responses indicating benefits and barriers related to tree stewardship. Results indicate that intervention messages had limited effect on these outcomes, and that level of engagement by the tree planting group was a stronger predictor of tree stewardship. We also found that tree stewardship correlated positively to heat protection measures, suggesting that environmental engagement may be an effective portal to reducing heat risk.

There is a pressing need for strategies to prevent the heat-health impacts of climate change. Cooling urban areas through adding trees and vegetation and increasing solar reflectance of roofs and pavements with higher albedo surface materials are recommended strategies for mitigating the urban heat island. We quantified how various tree cover and albedo scenarios would impact heat-related mortality, temperature, humidity, and oppressive air masses in Los Angeles, California, and quantified the number of years that climate change-induced warming could be delayed in Los Angeles if interventions were implemented. Using synoptic climatology, we used meteorological data for historical summer heat waves, classifying days into discrete air mass types. We analyzed those data against historical mortality data to determine excess heat-related mortality. We then used the Weather Research and Forecasting model to explore the effects that tree cover and albedo scenarios would have, correlating the resultant meteorological data with standardized mortality data algorithms to quantify potential reductions in mortality. We found that roughly one in four lives currently lost during heat waves could be saved. We also found that climate change-induced warming could be delayed approximately 40-70 years under business-as-usual and moderate mitigation scenarios, respectively.

There is an urgent need for strategies to reduce the negative impacts of a warming climate on human health. Cooling urban neighborhoods by planting trees and vegetation and increasing albedo of roofs, pavements, and walls can mitigate urban heat. We used synoptic climatology to examine how different tree cover and albedo scenarios would affect heat-related morbidity in Los Angeles, CA, USA, as measured by emergency room (ER) visits. We classified daily meteorological data for historical summer heat events into discrete air mass types. We analyzed those classifications against historical ER visit data to determine both heat-related and excess morbidity. We used the Weather Research and Forecasting model to examine the impacts of varied tree cover and albedo scenarios on meteorological outcomes and used these results with standardized morbidity data algorithms to estimate potential reductions in ER visits. We tested three urban modification scenarios of low, medium, and high increases of tree cover and albedo and compared these against baseline conditions. We found that avoiding 25% to 50% of ER visits during heat events would be a common outcome if the urban environment had more tree cover and higher albedo, with the greatest benefits occurring under heat events that are moderate and those that are particularly hot and dry. We conducted these analyses at the county level and compared results to a heat-vulnerable, working-class Los Angeles community with a high concentration of people of color, and found that reductions in the rate of ER visits would be even greater at the community level compared to the county.

This report serves as one of five individual documents developed over the course of Phase II of the Urban Forest Equity Collective. This document provides an overview of the Central Alameda pilot neighborhood assessment, engagement, and tree planting implementation process. It is intended to provide a transparent view into the decisions, points of analysis, and key themes derived over the course of this phase.

This report serves as one of five individual documents developed over the course of Phase II of the Urban Forest Equity Collective. This document provides an overview of the Sylmar pilot neighborhood assessment, engagement, and tree planting implementation process. It is intended to provide a transparent view into the decisions, points of analysis and key themes derived over the course of this phase.