Research on Urban tree research, tree soils & engineered soils

Tree roots in urban environment

ongoing cooperation

Urban tree & soil projects (Anu Riikonen)

Funding: various, e.g. City of Helsinki Public Works Dept., Maj and Tor Nessling Foundation, BRIDGE, 2003-

The urban tree research group at Viikki campus has worked with tree soils and root environment in several prjects. In a city, trees are planted in many different environments, soils and microclimates. City trees are expected to offer ecosystem services and to be aesthetically pleasing, but this may fail if tree health and vigour is poor.

Urban trees face a challenging environment. Microclimate, soil and human activity may damage trees and restrict their development. Microclimate is difficult to alter very much locally. Soil in planting areas is almost always removed during construction and needs to be replaced for planting trees. New soil can be chosen to fit the trees to be planted, within the limits set by technical requirements for load bearing etc.

Tree soils have been examined e.g. in Pohjoisranta, downtown Helsinki.

It is well known that small soil volume available to many street trees limits tree’s access to water, nutrients and soil oxygen, limiting tree growth. During the many decades tree soil is expected to function its properties often deteriorate and digging may damage roots. Street tree soils are often at least partially paved over and local nutrient cycling and hydrology tends to suffer.

Viikki street tree research project was founded by Helsinki City Public Works Department , University of Helsinki Department of Forest Sciences and several other collaborators. Main focus has been in structural soil research. Structural soils are one possible solution to improve tree root environment.

Problems related to street tree roots and soils are manifold. Some lead back to the nursery or planting stage, some develop later during the life of an urban tree. Girdling roots are sadly common problem in nursery trees.

In addition to the long-running Viikki street tree project, we have worked with street trees and tree soils on several shorter projects.

Helsinki City Public Works Department

Recent publications

Poster about tree growth and allometry


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