Post-transplant crown allometry and shoot growth of two species of street trees

Transplanting recovery of urban trees is an essential first step in their acclimation from nursery to challenging urban growing sites. Changes in crown allometry during this period are not well known. We followed annual shoot extension, crown structure and leaf area of Alnus glutinosa and Tilia × vulgaris street trees for six years from transplanting into their growing site. The growing site of Tilia trees suffered from excessive soil moisture whereas the Alnus site was more normal regarding soil water relations with periods of drought. The transplanting recovery of Tilia trees was delayed due to the deleterious influence of excessive soil water, but Alnus trees recovered substantially within the first 2–3 years. Leaf area in relation to branch basal area changed throughout the research period, indicating tree adaptation to new growing conditions.