Urban Vs. Natural Sugar Maple Growth: I. Stress Symptoms and Phenology in Relation to Site Characteristics
Richard E. Close, Phu V. Nguyen, and J. James Kielbaso
Abstract: This study provides a profile comparison of several tree growth, phenology, and site characteristics. The comparisons are between sugar maple trees in a forest stand and those in tree lawns on urban streets, both sites within 2 km on the Michigan State University campus in East Lansing. Sampled trees are from a stratified random group of healthy sugar maples. The study reports on significant terminal growth differences and much earlier leaf drop from the urban street site. Site soil moisture, air temperature, leaf temperature, relative humidity, and vapor pressure deficit were all significantly less favorable along streets, as was soil bulk density. Soil pH and the foliar nutrients N, K, Ca, Mn, B and Na were significantly less favorable along streets. The net effect of these urban conditions is a slow growing, restricted, low-density root system. This, in combination with prolonged water stress and high atmospheric demand, producing chronic water deficits in the tree crown, results in low vitality and reduced growth rates in the street trees.
Keywords: Sugar maple, growht, phenology, urban stress, water stress, street trees, natural forest, foliar nutrients, soil exchangeable cations, site characterization.