The researchers observed a significant inverse association between higher levels of green cover and lower direct healthcare costs, including the finding that individuals living near the most green space had adjusted health care costs of $374 per person per year less than those living near the least green space. Those in the highest decile of residential green cover were more likely to be white, older, male, and have higher education and income levels. Even after adjusting for sociodemographic and socioeconomic factors, the findings were robust.

To quantify the green space, the researchers utilized the Normalized Differentiation Vegetation Index (NDVI) satellite data. NDVI data “reflects the greenness found in satellite images of land cover and has been commonly used in the geospatial assessment of vegetation presence and viability as well as in the study of green space and human health.” Healthcare costs were obtained from the internal Cost Management Information System which compiles data from health service centers (hospitals, labs, etc.). 

One key strength of this study is the size and diversity of the population where everyone shares the same health care system. Differentiations in health care access are greatly mitigated as all members of the Kaiser Permanente Northern California system have virtually equal access. Another strength is the variety of land use types and topographies over the large area (25,000 sq miles) covered. The green cover-cost relationship observed is not constrained to specific landscapes or geographic settings. 

These findings support several previous studies on the health implications of green space and they exemplify not only the health benefit but also the economic impact of living near more green space. Researchers noted the existing body of literature that ties living near more green spaces to short and long term health benefits. High levels of green cover have been associated with better mental health, maternal-fetal outcomes, and fewer occurrences of cardiovascular disease, respiratory conditions, and mortality. This study supports nationwide efforts to incorporate green spaces into residential neighborhoods and urban greening.

The Harvard Forest and Amherst College researchers found that communities in the lowest income bracket, and communities with the highest proportions of people of color, have access to only about half as much protected land near where they live. These disparities persist across urban, suburban, and rural communities, and across decades.

But Harvard Forest authors Lucy Lee and Jonathan Thompson – with colleagues Neenah Estrella-Luna of Boston, and Kate Sims and Margot Lurie (’21) of Amherst College – didn’t stop at identifying the inequities in conservation. They also created tools that will be part of the solution.

First, they looked at lands that rank highly with conventional conservation criteria – such as wildlife habitat, drinking water, and carbon sequestration – and mapped their relationship with lands that rank highly for human environmental justice criteria – including communities with low income, high percentages of people of color, and high percentages of English language learners. They found that the two don’t tend to overlap.

They created a new prioritization system to help state agencies and conservation organizations identify specific opportunities for future conservation based on environmental justice criteria, and built a free, online mapping tool to highlight these opportunities on the landscape. 

Although their analysis focused on conservation solutions for currently undeveloped land, they also pointed to the importance of restoring existing developed land, including improving forest canopy in marginalized communities, and conservation partnerships that can increase access to existing open space. 

The Quarry Lane lot sits next to over 100 acres of City conservation and municipal land, and most importantly, the Busy Bees Preschool, which is notably diverse and also prides themself on their award-winning natural playground. If the land were developed, it would have not only increased flooding risk to the neighborhood and preschool, but would have removed both the trees and access to the abutting City land. NCLT specifically saw the project surrounding this land acquisition as a way to “Protect environmental justice neighborhoods from further disturbance, provide community building and outdoor learning opportunities, and promote nature-based play and outdoor recreation.” Thus, in partnership with other local conservation and municipal groups, NCLT has turned the space into a community garden that serves the local community and provides an educational experience for students at the Preschool.

In early 2021, to further these efforts, NCLT and Growing Places were awarded a $31,000 grant from the Amelia Peabody Foundation to work with stakeholders and the Preschool to build a multigenerational community learning garden. This past fall, they closed up on their first gardening season with the help of volunteers and the Busy Bees students and have already planned for the 2022 gardening season. Be sure to follow-along and check out their video on the project below.