by DJ Nowak, JR McBride
Journal of Environmental Management 32:383-3951991
Trees experience stresses in urban and in forested environments, although the sources and manifestations of stress may differ. In this study, the health of Monterey pine trees (Pinus radiata) was compared in the urban setting of Carmel, CA, and in the neighboring natural forests. Sixty stratified random 0.04-ha plots were sampled in forests around Carmel, and 783 Monterey pine trees within the city (also chosen through a systematic sampling design) were assessed. A number of site and tree data variables were collected, and a first stress rating that compared the trees’ crown volume and color to a hypothetical “ideal” tree was determined. A second stress index was developed based on the results of a principal component analysis (PCA) with ten crown values as inputs. The trees in the two locations showed stress very differently. In the forest, the most stressed trees were those experiencing significant competition, and these tended to be smaller trees, under 30 cm dbh, in suppressed positions in the canopy. In the city, the largest trees tended to be those showing the most stress, owing to greater amounts of internal shading and reduced shade tolerance due to age. Implications for management are presented.