Another response, re: Tree Planting Policies vs. Allergies

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.

Hello Ehren;

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.

re:  Tree Planting Policies vs. Allergies

So after my email last week to the City of Toronto, I was happy to get a number of responses back.  Initially just informing me that they were going to provide me with a proper answer … which was nice, and then eventually the actual answer.

I always knew that this would be a complicated issue and I imagine it is still a complicated issue given that cities are dominated by male trees and you have private property and natural areas to consider as well.  Ultimately, there is no real immediate solution but it is fascinating (and terrifying, not to mention painful) to me the impact a simple decision had on people so many years later.

I’m not one to demand immediate action because I don’t want to see trees cut down but I do appreciate that allergy-sufferers are now being considered in tree-planting policy.  Perhaps in the future, we can hope for fewer allergy sufferers and maybe one day someone like me can enjoy spring without shedding so many tears 🙂

I’m part of the City of Toronto’s tree planting
team (to use the non-technical term). The issue of urban trees and
allergies has been on our radar more and more, and we are developing
strategies to accommodate people who have issues with
pollen. To be clear, or goal is to increase the City’s tree canopy by
putting the right tree in the right place, and part of that is
understanding the needs of the City’s residents.

A small amount of background concerning urban tree
planting: In the 1940s it became increasingly common for cities in North
America to plant male trees as they were considered to be less “messy”
in that they produced little or no fruit
or nut debris which could clutter walkways, etc. Growers began focusing
on male tree stock to fulfill this requirement. As a result, over 60
years later, many cities have a tree population which leans heavily on
the male side. More municipalities are now realizing
the allergy-factor in this type of planting. Added to this,
privately-owned trees and those in naturalized areas are a mixed bag.

There are competing views as to how to tackle this
issue, but a popular theory suggests trees with perfect flowers (as
opposed to dioecious and monecious) are better for people with allergies
as the pollen is potentially more isolated within
the flowers and not wind-carried. For example, a Tuliptree (perfect
flowers) has pollen but it mainly stays within the flower unless
transferred by insects, while an Oak (monecious) relies on the wind to
disperse pollen over a wider distance. At the moment
the only tree widely available that does not produce pollen is Red
Maple ‘Autumn Glory,’ which we plant to accommodate homeowner requests
for allergy reduction.

I hope this answers some questions for you on this
large topic, and indicates that the City is trying to be sensitive to
the needs of allergy sufferers while increasing and diversifying
Toronto’s valuable tree canopy.