Below the Surface: In-Depth Investigation of Tree Development, Root Growth, and Soil Conditions in Structural Soils in Copenhagen, Denmark

Summary

Due to construction of new subway lines in Copenhagen, Denmark, a planting of 80 Tilia X europaea ‘Pallida’ established in 2000-2001 had to be removed in November 2011. The trees were established in two concentric circles, where each circle was a continuous stripe of structural soil (width 200 cm, depth 60 cm). Except for the planting hole, the circles were completely covered with paving. The removal of the trees provided a unique opportunity to investigate and evaluate root development and soil conditions on a real urban tree planting in structural soil. 

 In collaboration with the green space management of the city of Copenhagen, Forest & Landscape at the University of Copenhagen selected 10 trees for an in depth investigation of soil conditions, tree growth above and below ground and tree nutritional status. More specifically, physical and chemical soil conditions in the structural soil were analyzed via soil samples. Root diameter was measured on six soil profiles excavated in the structural soil stripe per tree (1 m, 1.9 m and 2.9 m; from both sides of the tree). Tree nutritional status was analyzed via leaf samples. Year ring analysis provided data on tree reactions to planting and climate. Quantitative data is supported by detailed photographic evidence. Findings will be presented with numerous photos and diagrams following the trees from their nursery life to establishment in structural soil and finally their removal.