Last night marked the final session of the first ever Oakville Tree Tenders Volunteer Training, a course designed to teach participants all about trees and urban forestry. The response to the course was overwhelmingly positive, and many of our graduates told us they now look at trees through new eyes!
The course was delivered by Oakvillegreen and LEAF (Local Enhancement and Appreciation of Forests) with funding from the Town of Oakville. Throughout the 4 sessions, our 24 new Tree Tenders learned about tree biology, urban forest benefits, soil, tree stresses, planting, tree care, tree policies and all the ways they could get involved in urban forest stewardship. Here are some highlights from the course:
On Day 1, we started off by talking about Oakville’s urban forest. We learned that Oakville currently has about 2 million trees, giving us a canopy cover of ~28%. But the urban forest isn’t just about trees – it’s a whole ecosystem that provides us with almost 3 million dollars worth of ecosystem services every year! Our urban forest improves air quality, reduces our energy use, stores carbon, decreases stormwater runoff, provides habitat and food for wildlife, improves our economy and keeps us physically and mentally healthy! Because of all those benefits, the Town of Oakville has a goal of increasing our canopy cover to 40%.
Much of this growth in canopy will need to occur on private property, which contains most of the town’s ‘plantable space.’ In order to grow our canopy, we’ll also need to overcome the many challenges that our urban forest faces, including a lack of age, size and species diversity, invasive pests and plants, and the everyday pressures that we put on urban trees, like soil compaction and road salt. The take-home message: we have to care for our trees if we want them to care for us!
Next, expert instructor Tooba Shakeel gave a great overview of tree biology. Our Tree Tenders particularly appreciated all the samples of leaves, bark and twigs that Tooba brought with her. We reviewed how trees use sunlight to turn carbon dioxide and water into sugar and oxygen. We also learned that trees breathe (respire) just like us, and that they act like giant straws, sucking water out of the soil through their roots and releasing it into the air through their leaves. Next, we talked about the 5 organs of a tree: leaves, stems, roots, flowers & fruit. Finally, we learned that trees grow from the top and that they don’t SEAL, they HEAL. Another important take-home message: tree roots are closer than you think – most are found in the top 2 feet of soil!
During our second session, we learned all about Tree ID with Jeff Dickie. Jeff taught us that trees can be identified by their leaves, growth form, bark, flowers, fruit, twigs and buds. When looking at these features, we should be noticing things like shape, arrangement of leaves and twigs on the stem, texture, colour, and even hairiness! Habitat can also give us clues on which species we might be looking at.
After being rained on during our first attempt to go outside, we took shelter and practiced using dichotomous keys to identify the samples that Jeff had brought with him. Once the skies cleared, it was back to the trails to try to identify some of the trees in the ravine. We learned that white oak can be distinguished by the shape of its leaves, and white pine has needles in bunches of 5.
Many of our Tree Tenders were even tasting black locust flowers by the end of the session! Jeff really encouraged us to pay attention to detail and look at the whole tree when attempting to identify it.
Saturday was a jam-packed day full of talk about soils, stress, selection, planting and care! Instructor Alex Satel started the day off talking about soils. By the end of his talk, everyone had a better understanding of just how important soils are for tree health! Soils are made of mineral material formed from rock, but they also contain organic matter and billions of microorganisms! Soil can have different textures – clay, sand and silt – and this texture will influence which species can grow in the soil. The texture and structure of soil can also influence the amount of micropore and macropore space available, which in turn affects the amount of air and water available to a tree’s roots. We learned that urban soils tend to lack organic matter and be highly compacted, which can be challenging for tree roots. Alex concluded by telling us that damaged soil is difficult to remedy, so preserving soil is key for tree health!
After wrapping up our discussion about soils, Alex moved on to talk about tree stresses. We learned that trees can become stressed due to a number of factors, including soil compaction, construction work, inadequate nutrients, too much or too little water, insect pests, diseases, competition or physical injury. Alex reminded us, however, that trees rarely die due to a single stress. Instead, a combination of factors can lead to tree decline and death. We also learned that while some insects can do serious damage to a tree (think Emerald Ash Borer), most insects are more of an aesthetic issue than a true health concern, and can be managed without the use of chemicals.
On our outdoor walk, we witnessed some tree stresses, including sapwood rot, weed whacker damage, improper planting, structural defects, EAB and compacted soil. We learned to recognize stress by both signs and symptoms. Alex urged us to consider cultural measures (the way we manage trees) when trying to reduce tree stress, as many of the stresses are caused by human behaviour and improper management in the first place!
To finish off the day, we headed back inside where Mara, Oakvillegreen’s Tree Planting & Stewardship Coordinator, talked about tree selection, planting and care. We discussed how native species are adapted to our climate and soil and support our local ecosystem, so we should try to choose native species when possible. There is a huge diversity of beautiful native trees, with different species suited to different soil and light conditions. Even in tough compacted soil, species like the Freeman maple, honey locust and hackberry can survive and start to grow canopy in newer developments.
When planting trees, we learned to make sure the root collar is level with the soil surface and to spread the roots out so they don’t girdle the trunk as they grow. In terms of care, young trees need regular deep watering (about twice a week with 6 gallons each time) and can benefit from a 2 to 4 inch layer of mulch. Just don’t pile the mulch against the trunk of the tree!! When pruning, we found out that we shouldn’t remove more than a quarter of the canopy in a single year, and we should make pruning cuts just outside the branch collar to allow the tree to seal the wound. After a full day of learning about trees, our Tree Tenders were eager to go out and share their knowledge with the world!
For our last session of Tree Tenders, Tom Pearson and David Burgess from the Town of Oakville came to talk to us about local tree by-laws and policies. We learned what we can and cannot do near town-owned trees, and about the application procedure required for doing work (e.g. driveway widening) near town trees.
Then, we moved on to talk about tree removal permits for both public and private trees. Any tree greater than 15cm in diameter at breast height (1.37m) requires a permit for removal. Most permits are issued with the condition that new trees must be replanted to replace the canopy. However, the exact conditions depend on the health, size and species of tree being removed. We also learned that when rebuilding houses, putting on additions or constructing pools, homeowners need Tree Protection Plans for their trees, which usually include Tree Protection Zones to protect the tree roots from compaction. All of these town policies and bylaws are in place to maintain our tree canopy, and it was clear that Tom and David were passionate about preserving trees!
We finished off the session with a presentation by Mara and Erica (from LEAF) on stewardship opportunities. Our Tree Tenders learned about opportunities to participate in Adopt-A-Tree programs, demonstration gardens, tree planting, invasive species removal, outreach and more in both Toronto and Oakville. The clear message was that no matter what your particular interest is, you can have a positive impact on our urban forest!
Tree Tenders is just the beginning!
We hope that this course will be the start of more community involvement in caring for our urban forest, and encourage our new Tree Tenders graduates to share their knowledge with their friends, family and neighbours! When everyone is aware of the benefits and needs of our urban forest, we all benefit!
Happy Tree Tending!