Protecting Aurora’s Tree Canopy

Our community expects our Council to build on the work of previous Councils and continue to take meaningful steps – both large and small – towards addressing environmental issues in our Town; and in particular measures by which we can address climate change.
 
The effective management of our tree canopy is an example of just one such meaningful step. In 2014, staff presented a report on the state of Aurora’s trees, and laid out a plan for how best to maximize the long-term viability of our tree canopy and take steps to mitigate the impacts of climate change on our community. In 2019, staff provided the 5 year update to this Council on the status of implementation of the recommendations of the UFORE report and the management of Aurora’s trees.
 
This week at Council, we were presented with a motion that sought to ask staff to take action that conflicts with the UFORE recommendations and/or duplicates work already underway. I could not support the motion as presented.
 
Aurora is like many municipalities across this province. Drive down any road. We have street after street of the same type of tree species. But worse still many of the existing trees and in particular the older more mature trees are of roughly the same age. Which means they are much more vulnerable to dying at the same time especially due to pest impacts.
 
We have basically 5 tree species that account for the bulk of our tree inventory and this increases the possibility of , “large-scale tree mortality in the event of a pest outbreak”
 
We saw this already here in Aurora, the devastating impact to our ash and elm tree population due to pest infestations and the huge loss of so many trees. It’s estimated that we are likely going to lose the rest of our ash trees in Aurora – or nearly 5% of our tree canopy. Clearly having a huge population of the same trees regardless of age represents a serious risk to the health of our tree canopy. You can’t sequester any carbon if you don’t have any trees! That’s why , “a key strategy for building both resilience and adaptive capacity of our tree canopy is to increase diversity…”
 
Aurora’s trees already sequester a lot of carbon. As was noted in the UFORE report, “the amount of carbon stored and sequestered per hectare in Aurora is relatively high in comparison to other southern Ontario cities.” In fact, Aurora’s carbon storage and sequestration is the highest of some of our York Region neighbours (compared to Markham, Richmond Hill and Vaughan).
 
But our trees are, predominantly the same species and predominantly young.
 
So we need to address that imbalance. And we do that through better tree canopy management. To achieve that we need to ensure our management plan focuses on “selecting low maintenance, well adapted and resilient species as well as proper planting sites, which foster the successful achievement of the goal of maximizing tree health and longevity”. And Staff are already doing that as we can see in the updates to UFORE recommendations 1 – 6.
 
The report does not recommend planting mature trees. It recommends PROTECTING mature trees, in particular, mature trees that have been identified as of a species that can withstand and/or mitigate the impacts of climate change.
 
Once you cut down a mature tree, you cannot get it back. Planting “as mature a tree as possible”, as this motion was asking council to do, is not an effective strategy to mitigate any loss of carbon sequestration.
 
To put it in simple terms, a tree is not a widget. You can’t simply replace a 20 year old tree with another 20 year old tree. That is not how an ecosystem works.
 
As anyone who has planted trees in their garden will tell you, the older a tree is at transplantation the greater the likelihood that it will not survive. And we need our trees to not only survive, we need them to thrive.
 
As outlined in the 2014 report and the subsequent action plan, a key objective to addressing the dominance of younger trees in our tree canopy is to employ a strategy to ensure an “uneven” or multi aged tree canopy.
 
The best way to ensure the long term viability and health of our tree canopy and increase its current and future ability to combat climate change is to have a greater degree of biodiversity and a multilayer (multi heights) and multi aged tree canopy. Staff have been working towards that goal for the past 5 years as we can see by the updates to UFORE recommendations 3, 5 and 7 .
 
With respect to protecting more mature trees, we have recently updated our tree bylaw to specifically address protecting trees that are 20cm in Diameter at Breast Height for example.
 
But more can be done.
 
Protecting and preserving our mature tree species and ensuring the protection and effective stewardship of trees that are younger (such as 7-15 cm or greater in DBH) and are of a variety identified as better able to handle climate change impacts is the best strategy for increasing the percentage of mature trees in our tree canopy now and in the future.
 
Trees are only one part of the puzzle. Shrubs also sequester carbon. And they are also under stress from climate change, and “may in fact be more vulnerable to pests or may be out competed by invasive plants.” We’ve already seen that with the highly invasive mustard weed in aurora.
 
It is estimated that the annual mortality rate of Aurora’s trees is between 2 and 6%. That means thousands of trees die every year. We will need to plant 25 – 70,000 trees to just to maintain our current tree canopy.
 
Many mature trees are on private property. We need to assist our residents to be better informed about how to care for their trees – watering and mulching for example, is vital to ensuring that the trees on their property thrive.
 
To manage threats to our tree canopy, we need trees that are of a good variety of sizes, diverse, and that can withstand climate change. Focusing on the age of a tree and its volume carbon sequestration, misses the point entirely.
 
In considering the motion that was before Council, and upon reading the 2014 report, the 2017 regional state of the forest report, and the 2019 UFORE recommendations update, it seems clear to me that contrary to the assertions in the motion, the most effective way to increase our balance of mature trees is to protect the ones we have. To quote the report, “…the protection and stewardship of existing trees is the most effective means of achieving greater tree cover and leaf areas”. Focusing on planting “as mature a tree as possible” to offset potential loss of carbon sequestration is, frankly, more about aesthetics than environment.
 
As the motion either conflicted with the recommendations of the UFORE report and/or requested staff action for work already done or underway (as outlined in the 2019 UFORE recommendations update) I did not support the motion.
 
Council voted 6-1 against supporting the first clause and voted 4 -3 against supporting the second clause of the motion. The motion in its entirety failed.
 
Under new business, at the suggestion of Councillor Gallo, Councillor Gilliland asked staff to provide an update on the UFORE recommendations. I supported that motion as I welcome further information on the meaningful steps this town is taking to combating climate change through the effective management of our tree canopy.
 
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