Article Bank

FOLLOWING PUBLICATION OF EACH ISSUE of the Ontario Arborist magazine, we load copies of our most popular columns and features here in our article bank. In addition to being an invaluable source of information, the online versions contain an added benefit not possible in the magazine – live links. So remember, if you read an article in print and want to visit a link but don't want to type in a long address, simply find the article here and click away. One caveat: articles date back almost 10 years so some of the links referenced in earlier publications may no longer be valid. We do our best to keep them current or remove outdated links but the web changes daily!

Author: Helene Miller
Issue: November-December 2009
A healthy urban forest is a great asset to any community, providing stormwater interception, energy savings, pollution reduction, carbon sequestration and social benefits. Promoting these positive attributes of urban trees has been going on for a long time. Unfortunately, for many years we simply had to say ‘Tree are good’ without having hard numbers to document the statement. Thanks to solid research however, many of the benefits of trees can now be documented and some can even have a dollar value calculated for them. The need to get that information out to the general public, but especially to those who make decisions related to trees and budgets, such as mayors, city councils, city staff and others, can be challenging given all the other competing needs in cities. Money for urban tree management is always tight, in part because trees are often seen as a nice extra rather than being understood as cost-effective infrastructure. The tree management budget is therefore often cut when times are tough. If tree benefits are truly understood, it is hoped that adequate budgets will follow.
Author: James Lane
Issue: July-August 2010
The Regional Municipality of York is an upper tier municipality located in the Greater Toronto Area. The Region covers an area of 1,776 square kilometres stretching from Lake Simcoe in the north to Steeles Avenue in the south. It borders Simcoe County and Peel Region in the west and Durham Region in the east. The Region provides a variety of services to its over 1 million residents including transportation services, transit, water, wastewater, emergency services, policing, human services and growth management. York is considered one of the fastest growing areas in Canada and its population is expected to increase to 1.5 million by 2031.
Author: Pat Kerr
Issue: March-April 2011
Everyone has a tale of the contractor who leveled a historic forest for a subdivision or the cranky neighbour who cut the majestic maple because it shed its leaves in fall. I lost count of the number of people who said in their own way, “people cut trees for stupid reasons” and one guy admitted sheepishly, “like my parents.” In 1970, Joni Mitchell hit the charts and brought the issue to the air waves with the line: “They paved paradise and put up a parking lot.” But it seems like Canadians are only just catching on to the idea that when you cut down a 200 year-old tree, it will be 200 years before it can be replaced.
Author: Patricia Thompson
Issue: July-August 2002
One of the highlights of owning property is the ability to plant and grow some of the wonderful trees that one sees while working in Toronto’s better gardens. The best specimen of redbud (Cercis canadensis) I’ve seen was in the front yard of Mrs. Rainsberry at 3 Banbury Avenue in North York. In my second year of monitoring her property (1991), she offered me a redbud seedling, 1 to 2 years old, and I planted it out adjacent to my front window. It is now 15 feet tall, 15 feet wide and has been blooming (and impressing neighbours) for more than five years.
Author: Peter Kevan
Issue: May-June 2002
The common hop tree is a rare plant in Ontario. It is the most northerly representative of the citrus family (Rutaceae) and ranges all the way from Mexico to southern Ontario where it is restricted naturally to growing in a few places along the shore of Lake Erie. Nevertheless, it has been planted elsewhere, presumably as an ornamental, and it thrives in Montreal at the Botanical Garden and in and around Guelph. It is winter hardy, thus, it is surprising that it has not been recommended for horticultural use. Let me explain...
Author: Peter Kevan
Issue: September-October 2002
Queen of the Canadian Carolinian trees and our only native species of magnolia, the cucumber tree is one of the rarest native trees in Canada. It grows in a few remnants of our Carolinian forest in southern Ontario. There, it is represented by some fairly large trees, less than 1 metre in diameter with crowns reaching to the canopy about 25 metres above the ground. It thrives best on rich, moist soils, but most such areas have been converted to agriculture and drained...
Author: Kevin Burgess
Issue: January-February 2003
Red Mulberry is a wind pollinated understory tree species that grows to 15 m and occasionally reaches into the canopy of deciduous forests. This monoecious/dioecious tree species flowers at leaf emergence in early spring and sets multiple purplish-red fruit in late summer.
Author: Peter Kevan
Issue: September-October 2003
When it comes to withstanding cold, Jack Pine is one of the hardiest of conifers, and the hardiest of the pines. It can be thought of as being a true Canadian, even though it does occur naturally at the very southern edge of its range in the northeastern and north central USA. It prefers to grow on sandy, well drained sites, including hilly terrain, with acidic soils. The waxy needles, in twisted pairs from 2 to 4 cm long, resist freezing winds. The long and slender reddish twigs tend to shed snow so that the branches do not break. The rough bark can also withstand being blasted by blowing ice. These same characteristics presumably counter drying conditions of the hot boreal summer. Summer drought, though, produces conditions ripe for forest fires, which, if not too hot, this tree can also withstand. The long, stringy roots, once used for stitching in making birch-bark canoes and tepees, provide strong anchorage against wind. This is one tough tree!
Author: Peter Kevan
Issue: July-August 2004
Hopeful monsters' refer to varieties of species that arise via mutation events and differ so conspicuously from the norm that they may be thought to represent different species or at least macromutations, or mutants (which used to be called ‘monsters’). Richard Goldschmidtmith (1940) used the term in his influential and controversial book "The Material Basis of for Evolution." For the honey locust, Gleditsia triacanthos, what is the hopeful monster? Is it the parental species type Gleditsia triacanthos triacanthos with its forbidding armament of spines, or is it the horticultural favourite cultivar, spineless and podless, Gleditsia triacanthos var. inermis?
Author: Peter Kevan
Issue: September-October 2004
Populus Balsamifera (also called P. candicans and P. tacamahaca) is one of Canada’s most wide ranging trees. It is characteristic of boreal forest species, growing almost to the tree line. Its southerly range includes the western mountains and the northern tier of the USA. It is the most northerly growing hardwood. Canada is also home to balsam fir (Abies balsamea) and balsam flowers (Impatiens spp. the touch-me-nots or jewel weeds (Balsaminaceae). ‘Balsamifera’ means balsam bearing, but what is balsam?
Author: Peter Kevan
Issue: May-June 2007
This Species Focus has been inspiredby the heavy, heavy cone set on our conifers in general, and on white spruce at the tree line around Churchill, Manitoba – in particular in 2006. White spruce, like jack pine and balsam poplar (tackled in my previous columns; visit the Fact Sheets link on is a Canadian tree. It ranges from Newfoundland into Alaska, with incursions into Maine, New York and across the southern Great Lakes’ watersheds. As a tree typical of the boreal forest, it shares its range with black spruce (Picea mariana). It is naturally absent from Carolinian forests of southern Ontario.
Author: Peter Kevan
Issue: September-October 2007
The Oak Ridges Moraine is an area of great natural beauty and conservation interest in Southern Ontario. It stretches across the top of Toronto as far east as Peterborough and Rice Lake. Lake Scugog is contained behind it. The raised land comprising the moraine is a well drained glacial deposit that influences the hydrology and the highly productive land to the south to the shores of Lake Ontario.
Author: Pat Kerr
Issue: November-December 2008
A firend called last fall and announced, “I planted an oak tree today.” “You’re feeling young?” I questioned. “No,” she replied. “It’s for my newest grandson. Perhaps his grandson will have a tire swing in it.” Planting an oak is a gift for tomorrow. We’ve loved it for flooring, kitchen cabinets and its magnificent shade. But our love affair with oak was self centred. We haven’t allowed it to regenerate, studied it or given it much attention at all. There is no emerald oak borer, oak rot or oak syndrome attacking our mighty oaks. Between a world war, depression/recession, the “now” generation and the “me” generation, oak was simply not a priority.
Author: Barb Boysen
Issue: January-February 2009
Many of you are familiar with the butternut tree. It can be a large beautiful specimen with the bark’s interesting diamond-shaped, flat topped ridges and its large spreading crown. The nuts of course are a dead giveaway – those oval, sticky, green orbs that thankfully aren’t produced as often as black walnuts – at least from a homeowner’s point of view. You may also have heard about butternut canker, the fungal disease that is threatening this species. It kills areas of the cambium on twigs and branches, spreads to the main stem and as the cankers spread, the tree is eventually killed. The symptoms include dead branches in the sunlit part of the crown (shaded dead branches are normal for butternut which is very intolerant of shade), and sooty black patches on the bark.
Author: Pat Kerr
Issue: January-February 2009
There are a lot of voices in the “tree” community talking about native species versus hybrids. On both sides of the debate, some see no room for compromise. Others see a mosaic of trees in Ontario. The issues are complex. But while the arguments continue, consumers are making the decision with every tree they plant. These choices will determine how we weather climate change and what we will pass on to our children...
Author: Peter Kevan
Issue: March-April 2009
There tends to be so much sumac in our landscape that familiarity leads to oversight. Yet, look around – roadsides, old fields and disturbed places are home to thickets of this small tree bearing its stout terminal twigs plush with velvet. In the fall, the leaves turn bright scarlet and all winter long, the fruits make a ruddy splash of colour. It seems that the name “sumac” derives from Arabic and that the Arabic word refers to the colour, even if of a different species. Often overlooked because it is so common and because it is plant of weedy sites, staghorn sumac has lots to commend itself.
Author: Michael Richardson
Issue: July-August 2009
If you have woodpeckers, you know you have woodpeckers. They are holding on to trees and the house, hopping up vertical surfaces, hammering loudly and throwing woodchips everywhere. Everybody recognizes woodpeckers, of which there are more than 200 species worldwide. With strong toes for clinging, upright postures, stiff tails to brace themselves, thick necks and chisel-like bills, woodpeckers are custom built to take advantage of the myriad of microhabitats that trees offer...
Author: Peter Kevan
Issue: September-October 2009
The Canadian Prairies is not noted for its diversity of trees but Manitoba maple (Acer negundo) is naturally a tree of the grasslands of Manitoba to the eastern half of Saskatchewan. There, it grows mostly along the banks of lakes, streams and rivers. In fact, this species is naturally the most widely distributed of all North American maples, ranging from coast to coast and south to Guatemala! In the US, it ranges naturally from New York to Florida and west into the middle and southern Rocky Mountains. It even occurs naturally in California. There are small native stands in Ontario, but its common and familiar occurrence in eastern Canada, including the Maritimes and into New England and the Pacific Northwest, has come about through its being planted and becoming naturalized.
Author: Oliver K. Reichl
Issue: November-December 2009
The Ontario Endangered Species Act (ESA), unchanged since 1971, finally received a major update in 2007. Since then there has been much debate, particularly in rural communities, about what is a species-at-risk (SAR) and the merits (or lack thereof) of the retooled act and its regulations. In this two-part feature, continued in the January/February issue of the Ontario Arborist, we’ll take a closer look at what this law means to the arboriculture profession in Ontario.
Author: Oliver K. Reichl
Issue: January-February 2010
The Ontario Endangered Species Act (ESA), unchanged since 1971, finally received a major update in 2007. In the second part of this series, we continue looking at how the ESA relates to the arboriculture profession in Ontario. While the first installment concentrated on introducing the Act, this feature will have a more practical focus. If you haven’t read Part 1 in the previous issue of Ontario Arborist you should probably do that first, even if only to acquaint yourself with some endangered species lingo...

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