A Dose of Nature: Tree Cover Density and Human Health

Department: Landscape Architecture
Research Centre: Urban Environments & Human Health Lab;

Project Title: A Dose of Nature: Tree Cover Density and Human Health

Bin Jiang (Co-PI, project manager), Chun-Yen Chang (Co-PI, National University of Taiwan), William C. Sullivan (PI, University of Illinois, Urbana-Champaign)

Project Funder:
The study was partially supported with two grants from the USDA Forest Service: One recommended by the National Urban and Community Forestry Advisory Council (Agreement #11-DG-11132544-333); the other from the US Forest Service Northern Research Station. We appreciate members of the Sustainability and Human Health Lab at Illinois for their participation in this research.

The demands and pressures of modern life are precursors to two of the most deadly medical problems we face today, cardiac disease and stroke. Long-term responses to stressful events put individuals at higher risk for these serious conditions. Fortunately, there is mounting evidence that exposure to urban forests enhances the resources that allow people to more effectively manage their stresses.

In these studies, we found that people not only prefer urban forests with greater tree cover density, but more importantly that they recover faster from stressful events as tree cover density increases. When it comes to urban forests and recovery from stress, every tree matters.

These findings, however, differed by gender. For women, there was a strong effect of tree density on psychological stress. For men the impact was seen in psychological, physiological, and hormonal measures of stress.

These findings are consistent with pervious work showing that people living in close contact with urban forests are more likely to live longer, pay attention better, have stronger ties to their neighbors, and experience a host of other positive benefits.

The bottom line: we should plant trees at every doorstep.


Jiang, B., Larsen, L., Deal, B., & Sullivan, W. C. (2015). A dose–response curve describing the relationship between tree cover density and landscape preference. Landscape and Urban Planning, 139(0), 16-25. doi: http://dx.doi.org/10.1016/j.landurbplan.2015.02.018

Jiang, B., Chang, C.Y., & Sullivan, W. C. (2014). A dose of nature: Tree cover, stress reduction, and gender differences. Landscape and Urban Planning, 132(0), 26-36. doi: http://dx.doi.org/10.1016/j.landurbplan.2014.08.005

Jiang, B., Li, D., Larsen, L.,Sullivan, W. C.  (2014). A Dose-Response Curve Describing the Relationship Between Urban Tree Cover Density and Self-Reported Stress Recovery. Environment and Behavior. http://dx.doi.org/10.1177/0013916514552321

Establishing dose-response curves for the impact of urban forests on recovery from acute stress and landscape preference. By Jiang, Bin, Ph.D., UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN, 2013, 195 pages; 3632060. http://gradworks.umi.com/36/32/3632060.html


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