The Town of Aurora’s Take on Tree Planting

November-December 2006

Topsoil Specifications (pdf) ...
Tree Planting Guidelines (pdf)...

THE TOWN OF AURORA, ONTARIO, is located about 40 minutes directly north of metropolitan Toronto. Like many small rural municipalities, Aurora started off in 1867 as an agricultural community and the head of the rail line. Typical of that era there were a few major industries, most notably the Joseph Fleury and Sons farm implement factory, makers of the famous Fleury plough.

Aurora remained the small country town until the early 1960s, when a growth spurt, brought on by the building of the Sterling Drug Company, resulted in a measurable growth in population, with my own family adding to that growth.

The population remained fairly static until the building booms of the early 1980s and has been ever increasing to this date. Through all of this growth, Aurora continues to maintain its small country atmosphere yet still offers the same big city services found in much larger communities.

Aurora Council has historically placed very high emphasis on providing resources for high quality of life experiences as witnessed by our many parks, trail systems, tree-lined streets, preserved woodlots and public recreation centres.

To put the size of our operation and the community we serve into perspective, the information that follows is a snapshot of the arboriculture side of our Department of Leisure Services, Parks Division.

In the Town of Aurora, with a current population of about 45,000, we have witnessed a steady increase in residential development for at least the past 20 years. Our residential street landscaping standards require that at least one street tree be planted per dwelling unit.

In an effort to get a better handle on the state of our urban forest and to better evaluate an appropriate level of urban tree maintenance, we recruited a forestry consulting service in the spring of 2006 to map and inventory our street trees. This process is expected to take at least two years to complete, but to date we have obtained excellent data for over 4,000 street trees. Many of which require some level of maintenance associated with pruning for structure, form and dead wood removal.

With a full-time staff of 10 people, we are fortunate to have five of our staff trained as municipal arborists who are heavily involved in block tree pruning, tree planting and some removals. The majority of our arboriculture maintenance such as pruning is conducted during the winter months. Larger more difficult removals are contracted out.

In recent years, we have seen changes on several fronts in terms of the health of our street trees in Aurora. Most significant among these changes has been in the deteriorating quality of our street tree planting locations and the actual tree planting methods employed by the landscaping industry.

As a municipal parks and forestry professional, I have often felt as though I was at the bottom of the food chain when it comes to convincing others of the importance and long term success of our urban forests. I am almost certain that I speak for others in my position when I say we quite often find ourselves on the losing end when facing off with the development industry, our counterparts in Public Works, and, in some cases, Municipal Planning Departments for an ever diminishing space to plant a street. I mean no disrespect to these folks as there are issues on all sides, however there is little doubt about what trees need to survive and thrive, and a quality planting site above all else is imperative.

Of course the irony behind all of this is the fact that every new home sales and marketing brochure depicts a wonderful canopy of tree-lined streets with inviting phrases such as “Forested Ravine Settings” or “Private Forested Enclaves” and “Majestic Tree Lined Streets.” We have all seen these ads and quietly chuckle to ourselves.

The fact is that the municipal urban forest is probably the most difficult living thing to manage and maintain and it’s getting even more difficult with pressures associated with reduced street tree planting opportunities as a result of the increase in housing densities, poor soil conditions and much reduced boulevard space.

This problem, coupled with our already limited arsenal of tools in our municipal tree forestry maintenance chest, is not only threatening our urban forest but placing the burden of tree health problems yet to unfold on our future residents, taxpayers and successors.

We all know that above all else, the single most important requirement for tree health is the soil planting medium. More often than not, virtually all land within new development areas in the GTA are subject to the ravages of large scale stripping and grading to facilitate the engineering components required by the municipalities.

The following is a typical scenario that is all too common in our part of the province in the land development industry.

Nutrient rich, fertile top soil which took centuries to form is aggressively stripped from former agricultural fields by huge heavy equipment then deposited in massive stockpiles for disposal at a later date. Unfortunately, the soil is almost always badly mixed with heavy subsoil and infertile clays. This material may also be trucked off site as it is often looked at as a liability to new home developers. After all is said and done, homes are built, curbs are poured, and the remaining soil is then painted back onto the lands in a thin layer on lawns and municipal boulevards.

Often referred to as top soil by the land developers and consultants, this material is so badly degraded and void of organic matter, both macro and micro nutrients, and applied in such thin layers that the long term survival of any tree planted in this medium will guarantee an almost certain recipe for failure.

We, in the Town of Aurora have been struggling with this issue for many years. We have seen the results of poor quality plantings on our municipal boulevards. We have had the calls from concerned residents in early July reporting insect infestations and later in the summer with scorched and dropping foliage and a number of other tree health related issues. Almost 100% of the time, the issues all boil down to soil conditions and the negative effects poor soils are inflicting on our urban street trees.

The big question is what can we do to affect a change to improve planting conditions and make some progress in convincing both the development industry and the associated professional consultants.

Early in the 2004, our Landscape Architect, Gary Greidanus, after numerous site inspections of the many street tree planting projects, decided he had seen enough, and that it was time for some major changes in the way tree planting was being conducted.

Gary proceeded to develop a completely new street tree planting detail and specification that would become the Town Standard for all municipal boulevard tree plantings. This standard involved not only improvement of the planting sites but requires developers to place a minimum of 300 mm of top soil in the entire boulevard.

We also developed a specification and detailed description of top soil planting medium. This is not only described but it is also necessary for the developer to have the soil tested and analysed for nutrient content and organic and non-organic composition. The bottom line now is if the soil does not meet our specifications, it will not be accepted and trees will not be planted until it is rectified.

Unfortunately, several landscape architectural and contracting firms have had the unpleasant experience of completing plantings not in compliance with our new specifications – despite the fact that our specifications were well documented, circulated and provided in the overall subdivision plans. Needless to say, site rectifications were made.

These changes have not been easy for the development industry to understand or accept as the need to improve planting conditions and planting techniques come with an increased price tag. With the fact that we seem to be in an environment of short term thinking where price drives everything and what happens in the future will be some one else’s problem, it’s very easy to overlook the long term benefits of proper planting conditions when dollars can be saved today. The long term costs of maintaining an urban forest under stress will far out weigh the short term costs associated with greatly improved planting conditions.

If there is one piece of advice I could give to others in our industry, it would be to develop their own standards and specifications for street tree planting and ensure that they are being implemented on site.

Be ready to fight for and defend the future of your urban forest. Obviously others outside of our industry place a high value on it, so should we.

Here are the five steps that will go a long way in improving the future survival rate and reducing the negative effect of urban stress on street trees

1. Develop planting standards and specifications.

2. Educate and communicate your standards and specifications to other stakeholders and the development industry.

3. Include your standards in the development plans and development agreements approved by your council.

4. Request written certification from the landscape architect or engineer involved with the project, confirming that the works have been completed in accordance with the standards and specifications.

5. Inspect the works yourself to ensure that planting sites and actual tree planting has been completed in accordance with your standards and specifications.

— Jim Tree, Town of Aurora

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