I received another email from the City of Toronto, except this one seemed less empathetic to the problems concerning allergies and simply providing me with facts. Interesting and good to know although I think I prefer better understanding what they are striving towards in terms of accommodating allergy-sufferers in the long-term.
response to your question regarding the planting of female and male
trees and the links you have included I provide the following
The urban forest in Toronto is expansive and includes approximately 10.2 million trees, covering an area of approximately 18,000 hectares. Of this area, it should be noted that more than 6,000 hectares is forest canopy within natural areas, primarily of native forest communities, such as oak woodlands.
For natural areas under City management we advocate a diversity of native species which are adapted to the local conditions, as well as a diversity of individuals within each species to promote resiliency. Monoecious and dioecious tree species are reflected in our tree population. Monoecious tree species have both male flowers and female flowers on the same tree. Dioecious tree species have the male and female flowers on separate individuals of the same species.
More than half of Toronto’s trees 54.1% are estimated to originate from natural regeneration. The remainder 45.9% are planted. The following link will take you to our street tree planting brochure.
the City’s objective of managing the urban forest in a sustainable
manner involves planting both female and male specimens
of dioecious trees in order to ensure natural regeneration. Increasing
species diversity to improve overall forest health and reduce
vulnerability to pests and disease and planting tree species that are
native to the Toronto area, is also an objective towards
a healthy sustainable urban forest.
60% of land in the City is privately owned and we have no control over
the tree planting activities on private lands.
Residual pollen from private trees and its associated health issues are
beyond our control.
City of Toronto is also committed to improving air quality and
recognizes the role that trees play in achieving this objective
by providing a constant source of oxygen and filtering harmful
pollutants from the air we breathe. The direct benefits derived from a
healthy urban forest include air pollution uptake, reduction of the
urban heat island effect and provision of protective shade,
climate change mitigation, reduction in storm water runoff, conserving
energy use, habitat provision and enriching local biodiversity.