Twenty Years of Change in the Tree Community in Forest Park

In 1993, 24 permanent sites were randomly located in Forest Park with one additional site in the Ancient Forest Preserve. Three 250-meter-square quadrats were randomly located at each site. All trees within each quadrat were identified to species, and the dbh (diameter at breast height) of each tree was measured. Saplings were members of tree species less than 10 cm in diameter and saplings were members of tree species that were less than 2 meters in height; basal diameter was measured for saplings. Data were initially collected in 1993. Measurements were repeated in 2003 and 2013 at the same locations using the same methods. We found significantly fewer live trees and live saplings (treesdbh) in each decade, although the rate of tree mortality appears to be slowing. When examined by section of the park (city, middle, far, old growth), the far section had significantly more live trees and saplings than did the city section, but there were significantly fewer live trees in all sections of Forest Park in 2013 as compared to 1993. Our findings suggest important implications for management of the park