Under ideal conditions trees have a life expectancy ranging from a few years to decades, centuries or even a millennia.
Tree health is affected by less than ideal causes such as non biological (abiotic), human, natural, or biological (biotic).
The 'human factor' includes habitat destruction, pollution and poor cultural practices. Planting too deeply, poor quality stock, lack of aftercare or space for roots creates unfavourable conditions for trees.
Natural abiotic factors include mineral deficiencies in the soil as well as climatic stresses. Examples are extreme temperature or moisture conditions, droughts and flooding.
Biotic factors are easily observed. These include fungi, viruses, bacteria, nematodes (parasitic worms), and wood and bark borer.
Under guidance of the Christchurch Town Council’s chairman John Hall, willows and other trees were planted along Oxford Terrace.
In 1878 oriental plane trees were planted along Cambridge Terrace between Montreal and Cashel Street bridges.
Plantings from over 60-100 years ago include the weeping willows along Park Terrace and Lombardy Poplars along Oxford Terrace.
The Christchurch Beautifying Association, formed in 1897, is an organisation that developed alongside the urban development of Christchurch. Their organised efforts and achievements have helped create Christchurch's Garden City image and identity.