Trees Grow Faster in Cities due to Lower Ozone

Eugene S. Takle
© 2003

Ozone is very chemically reactive and interacts with plants to reduce growth and vigor. Substantial tropospheric ozone is created in major cities due to photochemical processes in combination with products of combustion. High levels of nitrogen oxides (which interact to destroy ozone) in the urban environment compared to surrounding rural environments suppress ozone levels in the urban core and produce a result that rural areas surrounding urban centers have higher ozone than in the city. Gregg et al (2003) grew cottonwood trees in New York City and surrounding areas and found that rural grown trees produced biomass at only half the rate of those grown in the city. They accounted for other factors in the urban environment and concluded that the differences were due to the higher rural concentration of tropospheric ozone. Many plant species are more sensitive to ozone than cottonwood trees, so the authors suggest that ozone generated in cities but transported to rural areas is having significant adverse impact on plant growth away from urban area.

Reference

Gregg, J. W., C. G. Jones, and . E. Dawson, 2003: Urbanization effects on tree growth in the vicinity of New York City. Nature 424, 183-187.