Diversity of Trees for Manitoba Cities and Urban Areas

Diversity of Trees for Manitoba Cities and Urban Areas

Diversity of Trees for Manitoba Cities and Urban Areas

By Rick Durand

Do we have the capacity to diversify the Manitoba urban forests? This article will show you the challenges we have in our urban forests and how you can make a difference.

Challenges
Manitoba is one of the coldest regions in the world and the trees growing here must be as tough and rugged as Manitobans themselves. Another challenge for Manitoba trees is the very high pH of prairie soils, typically between 7.5 to 8.5. Most prairie soils rise in pH as one goes deeper into the soil. So, trees that may do well the first couple of years because they are growing in the upper layer of the soil, may decline in health in later years when the roots hit the lower layers that have a higher pH. With a higher pH soil, the tree has less availability to essential elements such as iron and some of the micronutrients.

Another huge challenge is our urban forests are under attack invading exotic insects and diseases along with the increase of extreme weather events that have resulted in significant tree losses in our urban forests.

The incorporation of prairie cities and towns has occurred within the past 150 years. During the early years, American elm, green ash and Manitoba maple trees were the urban trees of choice since they could be taken free from the river banks and they were best adapted to the urban sites. In 1975, Dutch Elm Disease (DED) was first reported in Winnipeg and eventually spread over the next 40 + years to the native range in Manitoba and Saskatchewan. Urban centres in Manitoba and Saskatchewan dramatically reduced the number of elms being planted and replaced elm planting with green ash. With the recent threat of introduced insects and diseases, such as Emerald Ash Borer on ash and Bronze Leaf Disease on aspen, urban forest planners need to look for new tree cultivars.

How to prioritize tree diversity in your community
One big step to achieve a diverse urban forest is that municipalities of all sizes are now considering trees as part of the infrastructure of that city, town or village. This is a major shift in thinking that trees have worth in the urban setting, and financial assistance for planting trees is more available. The general public is also much more receptive to tree planting. They see trees as being a part of the fabric of their community and as an agent to reduce the effects of climate change. This is a great opportunity for municipalities and individual home owners to plant a diversity of trees.

Diversity of tree species
The municipalities have a much more limited selection of trees since they must choose trees that are highly adaptable to harsh sites like along major traffic areas and residential streets. You, the homeowner is actually the key to urban diversity in the urban setting since you can provide regular watering, fertilizing and pruning along with providing some protection from the wind. This means the homeowner should choose different trees to what is planted on the streets, boulevards and parks.

A list of recommended trees
The establishment of the Western Nursery Growers Group (WNGG) tree trial in 2008 has helped define a variety of shade and ornamental flowering trees that are best suited to be planted in specific areas of the prairies. You might be surprised to know that the southern Manitoba site had the greatest number of recommended trees. For example, the City of Saskatoon has a much smaller list of recommended trees due to their shorter season and reduced amount of annual precipitation. The results of the phase #1 is provided at the WNGG website, www.prairietrees.ca .

The second phase of the WNGG tree trial began in 2021 that included an additional 75 new trees for testing. The second phase will be completed this fall (2025). The results of the second phase will be put on the website in 2026.

In 2024, I added one more key resource to the WNGG website called the Cold Hardy Tree List. This list provides the names of trees that are being grown by the major tree nurseries supplying cold hardy trees to the prairie region. I intend to revise this list annually since there are always new trees being added each year by the commercial nurseries. There are currently 260 trees listed as of February 15, 2025. Most of these trees should be available at the larger local garden centres, and some of the trees will be found at the small garden centres and box stores.

If you are wanting to plant a tree on your property you should first decide where you would plant the tree and determine the primary function of the tree. Do you want it for shade, colour, beauty or as a screen? Then, measure out how much available space the mature tree would have without interference from utility wires and buildings, decks and pools. Determine the amount of sunshine that the tree would receive during the day. Most trees prefer full sun for most of the day. I then would suggest you follow a two-step procedure while using the WNGG website (prairietrees.ca). Firstly, click on the Cold Hardy Trees List located on the brown ribbon and review the 260 trees listed. You will see that there is important information associated with each tree such as zone Winnipeg is in zone 3. If you require more information on these trees you can search it on the main web. The second step is to click on the WNGG Tested Trees, also located on the brown ribbon. You can search for your selected tree and see if that tree was evaluated by the WNGG. If so, you can then see if it is recommended for your area. Those living in southern Manitoba would look under the column titled MB South.

My top 15 shade and ornamental flowering tree picks

Large (over 10 metres or 33’):
Silver Cloud maple (Acer saccharinum ‘Silver Cloud’), Prairie Horizon Manchurian alder (Alnus hirsuta ‘Harbin’), Oasis larch (Larix siberica ‘Durcarl’), Lone Star linden, (Tilia cordata ‘BySkinner’) and Night Rider elm (Ulmus davidiana x pumila ‘Durby’).

Medium (7-8 metres or 23–26’): Prairie Torch buckeye (Aesculus x ‘Bergeson’), Courageous ornamental crab (Malus ‘DurLawrence’), Starlite ornamental crabapple (Malus ‘Jeflite’), Velocity ornamental crabapple (Malus ‘Sunsterile’) and Ming cherry (Prunus x ‘Ming’).

Small (5-6 metres or 16’–20’): Hot Wings Tatarian maple (Acer tataricum ‘Gar Ann’), Slim Pickings columnar ornamental crabapple (Malus ‘By1901’), Purple Spire columnar ornamental crabapple (Malus ‘Jefspire’), Princess Kay flowering plum (Prunus nigra ‘Princess Kay’) and Muckle plum (Prunus x nigrella ‘Muckle’).

It should be noted that I have not covered any of the fruit trees such as apples, plums, apricot and pears. Those trees are also a good choice in the urban forest if the gardener is willing to provide additional time and resources to manage a fruit crop.

To include native trees in your native-themed yard, you need lots of space. Most of the native trees are tall and wide. Large trees create shade, and this allows the gardener to choose many of the woodland plants that grow best in shady conditions. Deciduous trees such as: trembling aspen (Populus tremuloides), Manitoba maple male cultivars such as Baron (Acer negundo ‘Baron’), Hulk (‘Hulksun’) and Trailblazer (Acer negundo ‘ByPSN705’), paper birch (Betula papyrifera’), bur oak such as Top Gun (Quercus macrocarpa ‘Bydur’) and Bolt (Q. macrocarpa ‘Byargo) and American linden such as True North (Tilia americana ‘Duros’) are good choices. The best evergreen would be the native white spruce, Picea glauca. Make sure that you leave room for sunny spots so that meadow and prairie plants can thrive in the open, full sunlight environment.

Select the correct tree for your specific site and plant a tree that will promote urban diversity. To maintain your healthy urban forest, regularly water, prune and fertilize. Urban tree diversity is everyone’s responsibility!

“To learn more about growing fruit trees on the prairies with Philip Ronald, watch our video”
https://youtu.be/uFaMnZNLpGU?si=pV1yvIrkckZ4GyzJ

Published: March 2025