Trees Please Hamilton

Green Solutions to Air Pollution


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TREE TUESDAY – Emerald Ash Borer

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Adult Emerald Ash Borer

Have you heard of the Emerald ash borer? It’s story is rather dramatic, definitely not a bore. The beetle was first spotted in Windsor, Ontario in 2002 – suspected to have stowed away on wood packaging from Asia. Since then it has spread, killing millions of trees in Southern Ontario, Quebec and the Northern U.S. The ash borer does not move very far on its own – it typically flies 5km in search of another host tree – but humans have assisted its spread through moving around beetle-infected firewood. 

The borers lay their eggs under the ash’s outer bark, then the larvae eat their way through the inner bark – damaging the channels through which the tree transports water and nutrients. This eventually kills the tree within one to four years of infestation. Emerald ash trees in North America are vulnerable compared to trees in Asia that have co-evolved and built up defences to these beetles. 

This infestation has an extensive impact on urban areas like Hamilton that have planted many ash trees along streets and in parks. According to the City, by 2020 all of Hamilton’s ash trees could be killed. To prevent further beetle spread, the City passed a motion in 2012 to remove or treat 10% of Hamilton’s ash trees every year for ten years. Each ash removed would be replaced with a different species to diversify our urban canopy and make it more resilient to future pest attacks. Significant ash trees are being treated with an injectable pesticide, but it is not financially possible to treat all ash trees in the City. 

While inventorying in McQuesten, we found three ash trees. This is not a common find for us, but don’t get too excited because they were all mostly dead. 

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Information from our inventory in McQuesten

Sources:

https://www.hamilton.ca/home-property-and-development/property-gardens-trees/emerald-ash-borer

http://www.nrcan.gc.ca/forests/fire-insects-disturbances/top-insects/13395

 

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TREE TUESDAY – (Kentucky) Coffee Anyone?

Do you like learning fun nature facts? Well, after reading this post you will have a wealth of Kentucky Coffeetree tidbits to share with friends and family on your next neighbourhood stroll. 

The Kentucky Coffee tree was first encountered by Europeans in Kentucky, however it is also native to Southern Ontario. Its fruit comes in the form of a hard shelled bean with soft, sweet pulp inside. The beans had many uses to First Nations peoples – as game dice, as jewelry, and as a coffee drink (hence the name). Due to their utility, the beans were distributed by these people which helped increase the tree’s range. Since the beans have a hard shell, small animals are rarely able to chew through it and help with this dispersal. Wild coffeetrees today are best off in wetlands where the moisture degrades the shell and allows germination. 

Here’s the catch though, the raw beans are toxic to humans and some animals. They contain a toxin called Cytisine which is only neutralized after the beans have been roasted. While the First Nations people drank the roasted and ground beans, European settlers deemed this Kentucky coffee inferior to real coffee. Due to the threat of toxicity and its poor taste, Kentucky coffee has not caught on as a crowd favourite these days either.  

If you happen to live or work in the Crown Point neighbourhood, you can find a Kentucky Coffeetree (below) in St. Christopher’s Park. 

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Kentucky Coffeetree from our Crown Point Inventory

If you would like to have a Kentucky Coffeetree on City property near your home, they are available through the Street Tree Planting Program (www.hamilton.ca/treeplanting). This way, you will have a reason to share your new fun facts more often! 


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TREE TUESDAY – Mighty Honeylocust

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Honeylocust tree on Barton, ripe with seedpods

During inventory sessions we are never surprised to come across a honeylocust. In fact, over 10%, of all the trees we have inventoried are honeylocusts!

Considered a weed tree in many places, the honeylocust grows fast and is ideal for areas that are in immediate need of shade. This is why we often find honeylocusts around parking lots or beside streets. Hamilton’s Street Tree Planting Program offers the tree and its prevalence stems from tolerance to urban environmental conditions such as compact soil, salt, and drought.

Other characteristic features of this tree are its small, plentiful leaflets, and its long twisted seedpods.

The tiny leaflets are known for providing pleasant dappled shade, but are a chore to sweep up when fall comes. We are not calling the leaflets that name because they are small and cute, but because that is their official name. Each row of leaflets along a stem forms a compound leaf. On this picture below, you can easily distinguish the leaflets from the larger compound leaf.

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Honeylocust leaflets and compound leaves

The honeylocust seedpods are long and twisted, containing a sweet sap for which the tree is named after. The pods are pale green until they mature in the fall to become a reddish brown. Like other trees, producing seeds is energy intensive, so it was neat to see several honeylocusts exploding with seedpod production on Barton (pictured earlier). When trees are producing seedpods, they are diverting energy away from growth of branches or trunk. Due to this, they will likely not produce large seed yields year after year.

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Mature honeylocust seedpods


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TREE TUESDAY – Resilient Trees

 

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Trees in the Barton Centre parking lot

A struggling maple tucked away in the pavement of Crown Point’s massive Barton Centre retains few leaves. It’s barren branches stick out like accusatory fingers, “why has no one cared for me?” It is not alone. Apart from the hardy honeylocust, many of its parking lot comrades are defoliated or dead. They are isolated from the protection of other trees, and exposed to high levels of road salt, car traffic, heat and wind. Often when a new development is completed, contractors are required to care for the site’s trees for a certain period of time. We have our doubts that, by this point, the Centre’s 200+ trees are not being regularly loved. But perhaps trees are more resilient than we think? 

One way in which trees are able to survive in unfavourable conditions is to regulate their leaf temperature. An interesting National Geographic article explains how tree leaves can keep the same temperature, from tundra to tropics (link below). 

The article features a study of 39 species of trees on the North American continent by researchers at the University of Pennsylvania. These coniferous and deciduous species came from the chilly North all the way to the warm South. The study looked at the ratio of two different oxygen forms in tree rings since the specific ratio is linked to ambient temperature and humidity. Using this air temperature and humidity, they worked out the average leaf temperature of all 39 species to be around 21.4 degrees Celsius. 

The researchers believe that 21 degrees is ideal for photosynthesis, and that the trees aim to have their leaf temperature fluctuating about that point. So how do the leaves roughly maintain this temperature despite varying climates? They heat up in cool weather and cool down in hot weather by manipulating the processes of evaporation and light detection. In the heat, tree leaves bend downwards to avoid light, release water for the cooling effect as it evaporates, and reflect light with little hairs. In the cold, leaves are bunched together to reduce the rate of individual heat loss from each leaf. 

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Evaporation is one way leaves can cool down in hot weather

Although many Barton Centre trees are not happy in their environment, they may try employing some of the techniques above to survive. We’re cheering them on!

Sources:

http://phenomena.nationalgeographic.com/2008/06/11/tree-leaves-keep-the-same-temperature-from-tundra-to-tropics/

 


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TREE TUESDAY – Significant Trees of the World

We recently stumbled across a National Geographic article highlighting the stories of many culturally and historically significant trees all over the world. From the Neem tree of India to New York City’s Pear Survivor Tree, we learn that trees are places of meeting, prayer, protest, hope, and discovery. 

http://www.nationalgeographic.com/magazine/2017/03/wisdom-of-trees/

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Mango Tree, Mozambique. Source: National Geographic


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TREE TUESDAY – What are Those Bumps on Tree Leaves?

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Hackberry Galls found on Kenilworth Trees

If you see bumps like this on your hackberry tree, do not despair! We found these strange protrusions on a hackberry tree planted beside the Barton Centre on Kenilworth. One of our volunteers said that they were caused by bugs laying eggs and feeding on the leaves. Intrigued, we investigated a bit further. 

Turns out our knowledgable volunteer was right. These galls are produced by hackberry gall psyllids – tiny grey bugs, about one tenth of an inch long. The adult psyllids lay their eggs on new springtime hackberry leaves, then the new psyllid feeds on the leaves. In response to this feeding, the tree increases production of plant growth hormone in that area, which creates the galls. These pockets form a nice protective pocket around the bugs so they can eat tree sap within the gall throughout the summer. 

Although the galls can look unsightly and cause concern, they typically do not harm the host trees. Here are a few websites with more information: 

https://www.extension.umn.edu/garden/insects/find/insect-and-mite-galls/

http://lancaster.unl.edu/pest/resources/hackberrypsyllids.shtml


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Tree Planting at Amaolo Nature Sanctuary

The Hamilton Naturalists’ Club is hosting a tree planting at Amaolo Nature Sanctuary.  This is an unique opportunity because this sanctuary has limited public access so come check it out!
Due to the very limited parking availability, there will be a school bus charter leaving at 9:30am sharp from Dundurn Castle (look for the school bus in the parking lot)
Questions?  Email Diana at dgora@environmenthamilton.org

Amaolo Nature Sanctuary Tree Planting