May 2016
Parkallen
News In this issue… • The Value of Trees • Sort, Hide, and Seek • Hall Renovations • Hall Happenings • Growing Plans
Figure 1: A tree on 112 Street was removed after a sewer line replacement damaged its roots and significantly impacted the stability of the tree.
Keeping the Park in Parkallen By Jan Hardstaff BSc Horticulture, Landscape Consultant “They took all the trees, put ‘em in a tree museum And charged the people a dollar and a half just to see ‘em Don’t it always seem to go that you don’t know what you’ve got ‘til it’s gone
However, the intense pressure of infill development, utility installation or replacement and even construction during neighbourhood renewal also contributes to the stress and damage experienced by urban trees.
It is important to realize a tree’s roots do not grow mainly downwards. Although there may Joni Mitchell’s song “Big Yellow Taxi” be a taproot that plums the depths, (c. 1967-68) prophetically expresses there are also many large lateral roots as big as your arm that the risks of not maintaining balance between the demands of radiate out from the base of the development and protection of our tree to provide it with structural stability. In addition, to these large green space. roots are many fibrous roots and There are intense pressures on fine root hairs located in the top urban trees that put them at 30 to 60 cm that radiate out from risk. Some of these are natural, the tree and extend often well brought on by weather, stress beyond the drip line of the tree’s from drought, diseases and pests. They paved paradise and put up a parking lot.”
canopy. These finer roots take up enormous quantities of water which reduces the amount of storm water run-off. In addition, they act as a filter removing nutrients and contaminants from the urban watershed. The practice of trenching to reach and repair old utility services can seriously damage trees. Recently a sewer line was replaced on 112 Street (Figure 1). City Drainage trenched through the trees roots on the west and north side during installation and then continued through the sidewalk, curb and roadway to where the sewer line ties into the main line. Regrettably, this had a significant impact on the stability of the tree and consequently, Urban Forestry