Growth of street trees in urban ecosystems: Structural cells and structural soil

Abstract

Samanea saman and Peltophorum pterocarpum common to the Singapore streetscape were planted in structural soil and structural cell. These were installed with the intention of observing medium to long term plant responses to the various designed soil and cell systems. To verify root colonization in these systems under the sidewalk, root presence was measured using the ground-penetrating radar (GPR) in the fifth year following installation. GPR data indicated widespread colonization of roots in the designed soil and cell system. The highest root signal counts were concentrated deeper in the profile. Trees grown in open spaces were characterized by shallow root systems. Tree physical data identified that trees grown in structural cells had significantly greater growth performances. The observations here provided evidence that these systems served as an acceptable rooting environment when confronted with limited space and soil volumes common to urban environments.