Connecting with nature is predicted to be the garden trend for 2019, according to Garden Media Group’s 2019 Garden Trends Report: “Rooted Together — Reconnecting with the Natural World.” Link that prediction with findings from a research summary, “Urban Nature for Human Health & Well-Being,” recently released by the U.S. Department of Agriculture and the Forest Service’s National Urban Forest Team, which supports and encourages increased green space in urban areas.
The USDA report reviews research in five health categories: pollution and physical health; active living; mental health; stress reduction; and social health-cohesion-resilience. The consensus of the research in all five categories is that green spaces, such as parks, tree-lined streets and gardens, make humans happier and healthier.
Trees can improve air quality by removing pollutants such as carbon monoxide, ground-level ozone and particulate matter. When properly placed, trees can cool buildings and decrease energy costs. The effect trees and other plant material have on urban air quality is dependent upon the amount of air pollution, the plant type and the layout of plants in the overall landscape design. The reduction of air pollutants minimizes the symptoms of respiratory illnesses, which improves human health.
Diversity is key when selecting tree species in urban areas. Planting a variety of trees diminishes the possibility of one species producing large concentrations of pollen, which may impact the health of allergy sufferers. It also reduces the chance of a widespread elimination of a host tree species when attacked by a pest or disease, such as what occurred with the emerald ash borer and ash trees.
Data collected from areas with widespread tree removal to combat the emerald ash borer showed an increase in human mortality rates from cardiovascular problems and lower respiratory tract illnesses.
Although researchers were unable to explain this occurrence, it did demonstrate a relationship between human health and trees.
Air temperature in cities is generally warmer than surrounding areas due to urban heat islands — areas with buildings and impervious surfaces that direct sun and trap heat. Illnesses related to exposure to extreme heat, such as heat stroke and hypertension, are prevalent in urban heat islands during prolonged periods of extreme heat, partially due to the lack of trees and green space. Trees provide shade and have the ability to offer cooling through the process of evapotranspiration.
Parks in urban areas can reduce the effect of heat islands. The flow of cooler air in urban areas could be provided by strategically connecting areas of green space throughout a city. Kenosha has the added benefit of being located adjacent to Lake Michigan with its cooling effect on temperature during the heat of the summer.
The research summary includes evidence of the benefits of nature in regard to health and well-being. This information is helpful to urban planners and city foresters as they collaborate with health professionals to design healthy landscapes.
The research summary can be found online at: https://www.fs.fed.us/sites/default/files/fs_media/fs_document/urbannatureforhumanhealthandwellbeing_508_01_30_18.pdf
Jeanne Hilinske-Christensen is the interim Horticulture Educator for Kenosha and Racine counties for the UW-Madison Division of Extension. Submit plant care questions to the Master Gardeners Plant Health Advisers. Phone 262-857-1942 or email firstname.lastname@example.org