Greater density of tree canopy beyond the school grounds predicts higher academic performance of high school students

Li, D., Chiang, Y. -C., Sang, H., & Sullivan, W. C. (2019). Beyond the school grounds: Links between density of tree cover in school surroundings and high school academic performance. Urban Forestry & Urban Greening, 38, 42-53.

This study was based on the understanding that the outdoor environment surrounding schools can impact student performance. While other studies show a positive connection between green surroundings and performance of elementary school children, little research has studied this connection at the high school level. The aim of this research was to extend the literature on nature and academic performance by exploring the connection between tree cover density in school surroundings and school-level academic performance in high schools.

Researchers collected data on tree cover density surrounding 624 public high schools in Illinois and the academic performance of students attending those schools. Tree cover density data was based on satellite images generated by the 2011 National Land Cover Database canopy project. In analyzing the data, the researchers used the average percentage tree cover within five different circular buffer distances around the schools. The radii of these buffer distances were 0.25, 0.5, 1.0, 2.0, and 3.0 miles (approximately 400, 800, 1600, 3200 and 4800 m). Academic performance data was extracted from the Illinois State Board of Education Report Card which includes ACT scores, four-year graduation rates, college readiness, and freshman-on-track data.  ACT scores represent the school average in the areas of English, mathematics, reading, and science. Students with composite ACT scores of 21 or above are considered “college ready.”  Freshman students who have successfully completed at least ten semester credits and have no more than one “F” in a core course were considered “on track.” The four-year graduation rate variable refers to the percentage of students who graduated from high school within four years.

Results showed that tree cover density in school surroundings was positively associated with standardized test scores, a larger percentage of students performing well academically and college readiness. These associations held even after considering 19 potential variables known to impact student achievement. Variables considered included student characteristics (such as low income and single-parent families), school characteristics (such as class size), teacher and administrative characteristics (such as teacher retention), parental involvement, and school location (urban rural, or suburban). While some other studies show evidence of a positive link between greenness around schools and four-year graduation rates, this study did not. This discrepancy may be due to differences in spatial scale. Previous research focused on trees on school grounds. This study considered different buffer areas surrounding the schools.

This study found that higher tree cover density within half-mile to 1-mile distances around high schools predicts better academic performance for adolescent students. While further research is needed to demonstrate a causal relationship between tree canopy and student performance, these findings suggest that tree canopy in school neighborhoods can be an asset for education. The potential impact of tree canopy on academic performance should be considered by environmental planners and policymakers as they design and manage urban tree canopy.

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