Strengthening Community Climate Resilience: Citizens play a crucial role in caring for both public and private trees

This fantastic article by Colleen Zacharias was first published in the November edition of the Manitoba Master Gardeners Newsletter and is re-published here with permission. Colleen is the gardening columnist for the Free Press and you can find her writing in the Homes section of the Saturday Free Press. Email Colleen at colleenizacharias@gmail.com.

Strengthening Community Climate Resilience: Citizens play a crucial role in caring for both public and private trees

By Colleen Zacharias

What can people do to support trees on their private properties but also newly planted trees in front of their properties? Learning the reasons to care about trees is the first step towards actively caring for trees. Let’s begin with the example of newly planted trees on residential boulevards.

City of Winnipeg by-laws prohibit cutting, removing, moving, or pruning trees on public boulevards. It’s not my tree, some say. But when a mature tree dies and is subsequently removed leaving an empty space, the loss is felt keenly because all the nature-based solutions that the tree generated in front of a homeowner’s property are also lost: shading, cooling, filtration of urban pollutants, tree roots that act like a sponge in a deluge of rain, and carbon storage. Mature urban trees also contribute to significant curb appeal and increased property values. In addition, mature boulevard trees reduce the surface temperatures of our asphalt roadways to offset urban heat island effects. Typically, when a mature boulevard tree in a residential neighbourhood dies, a homeowner who was not previously invested in a tree’s care wants it replaced immediately.

Municipal governments today, however, face major challenges with increased service demands and decreased revenues. In Winnipeg, more than 33,000 elm trees have been lost to Dutch Elm Disease in the past five years alone. Over the last decade in our city, it’s been more about removing dead trees at considerable expense than planting new ones.

There is every reason for citizens to participate in giving newly planted trees in front of their properties the best chance to thrive, not least of which is the role that trees play in strengthening community climate resilience. Climate concerns are all around us.  Ordinary citizens often feel helpless in the face of a daily barrage of news stories warning of ecological disaster and potentially irreversible change.  While trees will not solve the world’s climate problems, trees are a proven means in helping to fight climate change. Trees create a haven of biodiversity for many species and are key habitats for bees and other pollinators. Trees are essential nesting resources for birds. Trees absorb and store carbon dioxide and trees also improve our physical and mental health.

For newly planted trees to provide these benefits and more in a changing climate that is expected to be hotter, drier, and subject to weather extremes, they must survive to maturity. If you are resistant to caring about or for a newly planted tree on your boulevard, don’t expect anyone else to provide your tree with what it needs to thrive. City crews do their utmost at the time of planting to give a hardy tree selection the healthy start it needs – ideally, proper planting depth so that the root flare is slightly above ground level, deep watering at the time of planting, and a five to seven cm layer of organic bark mulch around the tree which helps to suppress weeds and conserve moisture. As the organic bark mulch breaks down, it adds nutrients to the soil. Once a tree has been planted, however, city crews won’t be coming by regularly to check on the young tree’s weekly or even monthly progress.

Boulevard trees are routinely staked; however, staking should only be used to support a young tree for its first year. Tree guards are typically applied to the base of trees to protect the bark from rodent damage but if tree guards become broken or are left on trees too long, they can cause damage to trunks. Be aware and contact 311 city services if needed.

Providing water to a newly planted tree during its establishment phase (the first two to three years) is critical to its survival. Tree establishment requires supplemental watering. During the growing season, two or three adequate waterings each week are more beneficial than a daily sprinkling. In summer of 2021, when Winnipeg was experiencing drought conditions, I asked Wilbert Ronald, Jeffries Nurseries, how much water constitutes an adequate watering for a recently planted smaller tree. He suggests applying 25 litres and advised that water must be delivered directly to the root zone of the tree and should be applied slowly.

Mature trees should receive one deep watering (approximately 400 litres) in spring each year and again in late fall. After deciduous trees have dropped their leaves in late fall, give both deciduous and evergreen trees a deep watering before the ground freezes. Young trees have a restricted root zone. In the case of mature, established trees, the roots extend to or beyond the edge of the tree’s canopy or drip line. The roots of a mature tree will not take up water if it is applied directly adjacent to the trunk. Apply a deep watering just beyond the edge of your tree’s drip line.

Boulevards that are routinely sprayed with road salt during the winter months along with their typically depleted, compacted soils are harsh environments for both young and mature trees. In my older neighbourhood, which was developed in the 1970s, boulevard trees were planted directly into turfgrass. Fortunately, this practice has changed, and we are far more likely to see a mulch ring around newly planted trees.

But the next logical step is to replace monoculture grassed areas and to naturalize or rewild boulevards in low-traffic areas with a diverse mix of native, drought-tolerant, and pollinator-friendly plant species. Gerry Engel, president of Trees Winnipeg, says that the typical monoculture turf grass boulevard which is regularly mowed has little nutrient cycling and generally poor soil structure. “Poor soil structure has low water infiltration and low water holding capacity,” he says. “Naturalized areas promote healthy soil structure and significant water holding capacity by comparison,” says Engel. “In agricultural examples, regenerated soils can hold up to 10 times the amount of water when compared to depleted soils.” This is hugely important when considering the effects of storm runoff.

Engel would like to see the naturalizing or rewilding of boulevards to become common practice in urban areas. A biodiverse mix of native plants contributes to a healthier soil environment that includes complex webs of organisms such as tiny fungi and bacteria which provide important nutrients to help tree roots thrive. Winnipeg’s Neighbourhood Liveability By-Law #1/2008 does not make it easy to rewild or naturalize residential boulevards. The By-Law states that only turf grass can be planted within 1.0 m from the curb and only turf grass can be planted within 0.5 m from the public sidewalk. That doesn’t leave a lot of room for rewilding. In addition, digging is discouraged. Alternatively, the By-Law recommends that old newspapers be layered on top of the existing turf and that soil for planting be placed right on top of the paper. Selected plants must not have a mature height of more than 1.0 m. Nevertheless, planting a selection of native plants in an area outside the mulch ring around a young tree would provide your tree with a more natural environment than a monoculture of turfgrass. More information is available at
https://www.winnipeg.ca/publicworks/parksOpenSpace/Boulevards/PDFs/2017_
boulevard_treatment.pdf.

Looking for some plant suggestions? Aimee McDonald, co-owner of Prairie Flora Greenhouses, specializes in native prairie wildflowers and grasses. “In a low-traffic area, I would love to see lots of small, lesser known and unique prairie plants popping up spontaneously, encouraging every passerby to get a closer look,” she says. “It would be full of plants beneficial to wildlife.” For example:

• Cutleaf Anemone (Anemone multifida)
• Three-flowered Avens (Geum trifolorum)
• Blue Grama Grass (Bouteloua gracilis)
• Prairie Crocus (Anemone patens)
• Black-eyed Susan (Rudbeckia hirta)

Often, we see young trees on private properties in residential areas that have been planted into rock beds. Rock does not break down to improve soil. In addition, mounds of crushed black granite rock in tree and shrub beds absorb heat from the sun and raise the soil temperature. Pity the poor tree whose roots are struggling beneath a layer of landscape fabric and crushed rock.

A generation is loosely defined as the average period from the birth of a parent to the birth of a child and is generally considered to be about 20 to 30 years. Winnipeg has a tree pruning cycle of 31 years which means that some public trees are pruned only once, possibly twice in their lifetime. That is unacceptable. As citizens we can make our voices heard by contacting our elected officials.

It’s not difficult for most of us to keep an eye out for the health and wellbeing of a newly planted tree or existing mature tree in front of our house. You may want to become involved in helping to create green corridors in your neighbourhood and community. Not-for-profit organizations such as Trees Winnipeg and Trees Please advocate for street trees and provide volunteer opportunities.