‘Greening’ the city-scape Trees define and soften city spaces

Press, 12 March 1985, Page 14

‘Greening’ the city-scape Trees define and soften city spaces

Christchurch enjoys a reputation as a city of pleasant parks and splendid trees, which we can protect and enhance. Its traditional English character is attributable not only to its fine old buildings, but also to the character and vivid seasonal changes of its many large, deciduous trees. Trees are by far the most important plant material for lending scale to our living environment, so that we feel in proportion with and can more easily relate to our surroundings. Their soft, ever-changing forms provide visual relief, and a reminder of nature in our sometimes harsh city environments.

Architectural role Trees have a vital architectural role to perform in any city. Besides providing scale, they are also articulate space, screen, and soften built forms and harsh paved expanses. They link buildings and open spaces together, define areas of distinct identity, and help provide the underlying structure to the urban environment.

A city must have a rich variety of spaces, the arrangement and character of which give the city its essential quality. Parks offer a welcome relief of foliage, shade, water, and flowers. More inner city parks are now being established in Christchurch. The most recent is Peter Scoular Park, in Tuam Street. An exciting proposal for the future is the redevelopment of Victoria Square, offering a great

opportunity to provide a refreshing green oasis in the heart of our city. Open-space framework Urban dwellers are subjected to many environmental stresses which can be relieved by an adequate open space framework with associated tree planting. Major components of the open-space framework are:

® Streams/rivers — biological corridors which should be developed as many-purpose greenways to provide the basic framework for walking, and for tree planting. • Parks — urban parks should not only cater for traditional sporting activities. Many people now favour recreational pursuits which require a more natural setting. Existing parks should, where possible, be divided into a variety of different sized spaces with tree planting and “woodland” areas, to provide for both active and passive recreation. ® Streets — streets should provide more than just their basic service. It is important that visual character and human needs are recognised as essential aspects of street design. Trees, more than any other element, can humanize a street, and make it a better place to live.

The Avon and Heathcote Rivers, Hagley Park, and the Port Hills are major resources of open space in Christchurch. Although we are well endowed with other parks, they are in some cases isolated and road-bound,

rather than forming part of a continuing open space. Selection of species Physical conditions Choosing tree species precisely suited to the specific environment will ensure good growth rates, and low maintenance. We have to carefully consider these conditions. © climate — the trees should be sufficiently hardy to succeed in the

climate of the district, involving factors such as rainfall, temperatures, prevailing winds, frost, seaside conditions, shading, and atmospheric pollution. © Soil type and natural drainage — they should be a species which will thrive in the soil and situation given them. Tree species growing locally are usually a reliable guide, as certain trees are responsive to certain soil types. Christchurch generally provides excellent growing conditions for a large variety of trees, although some problem areas exist because of poor soil, strong winds, drought or exposure to sea-spray. However, these problems can be overcome by a careful selection of species. Built environment ® Roads and services — services present the most frustrating problem for those involved in the planting of street trees. The typical street is a minefield of underground services, which are often concentrated in the grassed berms or medians.

When combined with other constraints such as overhead wires, lighting, and road sight lines for traffic safety, the planting of trees in a street can be severely limited. Informal grouping of trees, as opposed to the traditional concept of regimented avenue planting, is particularly affected by indiscriminate service location.

© Adjoining properties — care must be taken to avoid loss of view or sun, which can cause trees to be severely pruned or re-

moved. Individual root systems also need to be considered. Such problems can generally be avoided by selecting trees with suitable growth habits, and by the continued involvement of residents in tree planting schemes.

Identity areas The wider cityscape can be divided into areas with a particular identity, defined by the open space and development patterns, and the physical conditions of each particular area.

A select list of suitable framework trees can then be compiled for each area, emphasising distinct identity and individual neighbourhood compartments. The restricted range of species would help create a more cohesive visual structure within the city. The individual property owner can help strengthen the planting structure by choosing species already growing locally, or used in the street, and with a character which would enable them to form part of the general landscape composition. If in doubt it is wise to seek professional advice. I have outlined the structural importance of trees to the urban landscape, and some of the problems involved. It has been stressed that a tree should not be perceived simply as a horticultural specimen, but looked at in the wider context of its structural or architectural role.

The effective provision of trees can make the urban environment a much more pleasant living experience.