Green Infrastructure: Condition Changes in Six USA Urban Forests

Abstract

This study is one of the first to consider both public and private trees in an urban forest in the United States of America. The size and health conditions of urban forest trees are determined by many factors ranging from the genetics of the individual trees to environmental factors and anthropogenic issues. Tree size was measured by dbh (diameter at breast height, which is measured at a height of 1.4 meters in the United States) and tree health conditions were calculated by a point system. Tree health was assessed by identifying signs of decline or hazards on the crown, trunk, branches, base and roots. Then, the decline signs were counted and a value was assigned based on the number of decline signs. Our data indicates that there is a general tendency for the smallest trees to have the best health condition. When considering the relationship between the size of the trees and overall tree health conditions, we can state with certainty, that there is a strong negative correlation between the size of urban trees and the health condition of urban trees; conditions decrease or worsen as size increase.