Check out this photo from Simon Bell.

“I would never have noticed them myself, but Martin Bosch was staring intently up into a maple tree in St. Georges Park in Guelph yesterday. What was he looking at? A mother Eastern screech owl and five babies! Quite amazing.”

To enjoy some more os Simon’s great photography, visit

Photo: Simon Bell

Mycorrhizal partnerships are symbiotic, or, mutually beneficial, relationships between plants and fungi, that take place around plant roots.

Mycorrhrizae  in the soil have been shown to be essential to plant growth by facilitating the uptake of minerals and nutrients by breaking them down into available forms for the trees to use  as well as stimulating fine root development that lengthen the life of the roots.

They can also protect plants from drought, predators (such as nematode worms), and pathogens (micro-organisms that cause disease). Furthermore, in areas polluted by toxic heavy metals, fungi can buffer their plant partners against harm.

A diversity of fungi is desirable, as different fungi specialize in different functions, as mentioned above. One fungal species may be good at taking up particular nutrients, while another will be better at producing enzymes.

Threats to Mycorrhizae
Mycorrhizae can be damaged by soil compaction and disturbance, as well as by the use of certain chemicals, all of which occur in intensive agriculture and landscape maintenance.

Applying large amounts of inorganic fertilizers to young trees, can suppress the development of mycorrhizae. Excess nitrogen, whether from fertilizer use or atmospheric pollution, affects the reproductive parts of the fungus, and so could have long term effects on fungal populations.

Development practices have greatly affected the life in the soil.  Adding a handful of decaying leaves into a hole that a new tree is planted in can inoculate the soil and help bring back the organisms that the trees need so much!

Research into the interactions between old trees and their moss that harbours cyanobacteria, produces a combination that contributes to the long-term health of surrounding trees. They are somehow fertilizing the ecosystems around them.

Without the presence of these old trees, the health of the surrounding younger trees is degraded.

Read more about this  interesting research HERE.


Diana Beresford Kroeger

Diana Beresford-Kroeger, botanist and medical biochemist,  was the keynote speaker at the Ontario Urban Forest Council Conference held in St Catherine’s in autumn 2010.

In her presentation Diane talked of trees as extraordinary, complex species. In our earth system the trees connect us to the sun as they oxygenate the planet. She spoke of the vast tonnage of tri-terpenes that are liberated by the boreal forest like a detergent cleaning the air with natural fungicides and natural antibiotics. They hang onto cloud droplets and regulate the weather of the world.

Diane talked about democracy of the land and how we need a land agreement between the species for care and sharing. And then she detailed specific trees that give massive carbon sequestration and can help us withstand the huge flow of severe weather and UV exposure that climate change is bringing .

If you want to learn more, there are a few copies of her latest book, The Global Forest at the Guelph Public Library. It is a fascinating read. You won’t be disappointed.

Great article from Mark Cullen in The Toronto Star regarding the importance of trees in urban neighbourhoods.

Here is an excerpt:

For a long time it has made eminent sense to me that we need more trees in our urban spaces. If we spent more time and money on the planting of trees and the maintenance of the ones that we have, can you imagine the difference that it would make?

Here are some points to ponder from a variety of studies including one conducted in Chicago by the University of Illinois called the “Vegetation and Crime Study.”

Check out a full list of referenced studies here:

Consider what trees do in our urban area:

  • Compared with buildings that had little or no vegetation, buildings with high levels of greenery had 48 per cent fewer property crimes and 56 per cent fewer violent crimes.
  • Trees encourage physical activity. Comfortable outdoor environments are more conducive to encouraging exercise. Research in the Netherlands and Japan indicate that people were more likely to walk or cycle to work if the streets were lined with trees. Residents feel better and live longer as a result.
  • The proximity of green space (and trees) to people’s homes increases the likelihood residents will choose to walk over other forms of transport.
  • Green play sites reduce the symptoms of attention deficit hyperactivity disorder (ADHD).
  • Trees and green space helps reduce mental fatigue and stress and has important benefits for childhood development.
  • A survey of 1,350 real estate agents showed that 85 per cent believe that a home with trees would be as much as 20 per cent more saleable than a home without trees.
  • CP Morgan, a developer in Indiana, found that his wooded lots sell for an average of 20 per cent more than similar non-wooded lots.

Add the well documented facts that trees cool the atmosphere, produce oxygen, sequester carbon, filter and slow storm water runoff, and transpire moisture on hot days. You get the picture.

The Toronto Urban Forestry Study, “Every Tree Counts,” estimates the value of Toronto’s Urban Forest ecologically as providing “at least $60 million in ecological services each year”.

In Toronto, there are about 4 million mature trees in public spaces and 6 million more on private land. At one time, the tree canopy in Toronto covered almost 40 per cent of our land area; today, it covers approximately 20 per cent. The tree canopy in Toronto has been in decline since the 1960s.

As you contemplate all of these facts, think about the impact more trees would have in urban spaces in our lifetime — and that of future generations.

Mark Cullen

Read the full article

GUFF Guelph

The ‘poor steward’ has compacted the soil over the roots from April to the end of September. This will severely impact the health and longevity of the sugar maple. The ‘good steward’ however has carefully piled all of the construction material outside of the dripline of the mature tree. He realizes the value of this tree to his property.

The Poor Steward - Material Around The Trunk Is Compacting The Soil

The Good Steward - Construction Materials Are Stacked Outside The Dripline

The most serious pollutants in the urban atmosphere are ozone, nitrogen oxides (NOx), sulfuric oxides (SOx) and particulate pollution. Ground-level ozone, or smog, is created by chemical reactions between NOx and volatile organic compounds (VOCs) in the presence of sunlight.

High temperatures increase the rate of this reaction. Vehicle emissions, emissions from industrial facilities, gasoline vapors, and chemical solvents are the major sources of NOx and VOCs. Particulate pollution is made up of microscopic solids or liquid droplets that can be inhaled and retained in lung tissue causing serious health problems.

Large shade trees can reduce local temperatures by 3 to 5 °C.

It is also important to shade parked cars.  16% of hydrocarbon emissions are evaporative emissions of fuel and volatilized plastics from parked vehicles.

Edinburgh Road South - Where Are The Shade Trees?

Evaporative emissions and the exhaust emissions produced during the first few minutes of engine operation significantly affect local microclimate. If cars are shaded in parking lots, evaporative emissions greatly reduced.

Cars parked in parking lots with 50% canopy cover emit 8% less through evaporative emissions than cars parked in parking lots with only 8% canopy cover.

The volatile components of asphalt pavement evaporate more slowly in shaded park lots and streets. The shade not only reduces emissions, but also reduce shrinking and cracking of asphalt so that maintenance intervals can be lengthened.

Trees also act as filters intercepting airborne particles and reducing the amount of harmful particulate matter. The particles are captured by the surface area of the tree and its foliage. Large,  broad-leafed trees with dense foliage collect the most particulate matter.

Guelph Urban Forest Friends

Investing in Trees – Trees are good for the environment and the bank book, too
By Virginia Gauley  GRCA Forester

Imagine your neighbourhood without any trees. It would look pretty dismal, more like an industrial area than a residential neighbourhood.

Trees are an important part of our lives, offering us a sense of place within our community and providing us with many benefits on a daily basis. Trees can provide us with a shady place to have a picnic on a hot summer day, a quiet location for a walk along the river or perhaps a serene setting to read a good book.

But trees have many practical uses as well, especially for those of us living within a city, where they can reduce noise from busy streets, increase privacy in backyards and keep houses cool in the summer.

We don’t often realize that the trees growing within our neighbourhood are saving us lots of money. Planting trees is really like making a long-term investment.

The benefits of trees extend far beyond their ability to provide shade and privacy.

We derive economic benefits from trees in many ways and not just in terms of forestry resources such as lumber and timber products. Trees are able to reduce the amount of money that we spend on treating and managing our water supply, heating and cooling our homes, combating air pollution and producing energy. Trees are especially important in an urban setting where they are needed to maintain a healthy environment by cleaning the air and water, and counteracting the effects of urban growth.

Cities spend a lot of money installing storm water management facilities and, through the Grand River Conservation Authority, managing flood control systems.

Trees can offset these costs by intercepting rainwater and reducing the amount of runoff that must be managed in the urban area and by storm water management facilities.

A study in Charlottesville, Virginia showed that when tree cover dropped eight per cent between 1976 and 2000, the amount of runoff increased by 19 per cent. It would cost about US$6 billion to build storm water retention ponds and other engineered systems to intercept the runoff that had previously been captured by the trees.

Reduce runoff
The study also reported that the city’s tree cover captured an estimated 7,200 tonnes of carbon per year and removed close to 104,300 tonnes of pollutants from the atmosphere. The dollar value placed on these services was estimated to be US$567 million.

The Grand River watershed is about one-third the size of the Charlottesville study area, however, similar results could be expected based on population size and density of the Grand River watershed as a whole.

The urban core and other parts of a city where tree cover is scarce are often referred to as “heat islands.” These are areas where air temperatures are often much higher than the surrounding area, sometimes by as much as 3C to 5C.

Higher temperatures in urban heat islands bring with them increased energy use, mostly due to a greater demand for air conditioning. As power plants burn more fossil fuels, they increase both pollution levels and energy costs.

Wintertime also brings on higher heating costs in areas with low tree cover due to the cooling effects of the wind and weather on an exposed building.

Planting trees strategically at various locations around an otherwise exposed building can reduce heating and cooling costs by as much as 40 percent.

Trees are most effective in reducing cooling costs when they shade air conditioners, windows or walls, and when located on the side of the home receiving the most sun. Windbreaks on the north side of a house are most effective in the winter for blocking cold northerly winds.

Over their lifetimes, trees can be much less expensive than air conditioners and heating systems, and the energy needed to run them. (More information is available on the Vancouver-Clark Washington Parks and Recreation website.

So we know that trees can save us money, but how do they make us money?

Trees create a pleasant environment. They create a sense of place and provide us with a sense of security. They even make us want to shop!

A study conducted in Vancouver-Clark, Washington showed that people shopping in a treed business district were inclined to shop more often, for longer periods of time, and to spend in the range of 11 percent more for the same product than if it was sold in a treeless business district. This shows great promise for small businesses located in well-established neighbourhoods where the tree canopy is fully developed and mature trees line the city streets.

Trees help raise real estate prices. The homes located on a well-treed street are often priced higher than a comparable home located in a relatively treeless neighbourhood. Urban foresters and real estate agents have found that trees increase the real estate value of both residential and commercial property. American Forests estimates that a well-landscaped home and mature trees will increase the value of the property by 15 percent. That is an additional $22,500 on a home valued at $150,000.

Target for canopy cover
There is no question that trees add value and benefit to our everyday lives. But there is also financial incentive involved in planting trees that will help keep money in your own pocket and help to maintain the health of our environment for the long term.

American Forests, a not-for-profit organization involved in assessing the value of tree cover on the landscape, recommends that tree leaves should cover 40 per cent of the area within a city. This minimum area would ensure the sustainability of the urban ecosystem and maintain a balance between urban growth and a healthy environment. The urban centres in the Grand River watershed vary from a low of 24 per cent in Brantford to a high of 29 per cent in Waterloo.

The goal of 40 per cent is attainable and can be accomplished through community effort and dedication.

There are currently numerous groups committed to reaching this goal in the Grand River watershed and they have already achieved significant results, but every effort made is a step in the right direction. So in the end, take a moment to plant a tree, save some money and make an investment into the future of your community.

More info at
Watershed Forest report 2004   (Guelph canopy is 27% : Source GRCA).

Benefits of Urban Trees

Trees are a very important part of our urban environment.

Urban trees filter air, water and sunlight and reduce air pollution. They moderate local climate, slow wind and storm water run-off, and shade our buildings to conserve energy. Trees protect us from UV radiation that causes many cancers. Trees are also critical in cooling the urban heat island effect, thus they reduce the number of unhealthful, smog days. Walkable cities need tree shade on our streets and paths to support healthier citizens. Beauty from trees is an added community benefit.

The economic benefits of trees have been understood for a long time…..and justify expenditures to maintain them. For example, a deciduous tree planted on the south and west of a building offers shade that cools the building during the summer, but allows the sun to warm it in the winter after the leaves fall. Businesses flourish, people linger and shop longer, apartments and office space rent quicker, tenants stay longer, property values increase, new business and industry is attracted. (USDA guide). They have also been shown to increase property values by 10-23%.

The physical effects of trees: the shade, humidity control, wind control, erosion control, evaporative cooling, sound and visual screening, pollution absorption and precipitation, all have economic benefits.

UV protection from tree shade reduces costs to the health system (Skin cancer is the fastest growing cancer in Ontario and walking lowers the rates of obesity, heart disease and diabetes). We need shaded streets for more walking and biking. Trees also reduce storm water management costs through slowing the runoff and stabilizing river quantity and quality. They provide shelter and food for animals and pollinators.

Guelph Urban Forest Friends

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