New species, irrigation to combat climate change

By Hanneke Brooymans
Edmonton, Canada (October 31, 2009)- Edmonton’s urban forest could sprout a slightly different look under the city’s first management plan expected by the end of the year. People are used to thinking about the city’s “grey” infrastructure, such as sewers and roads, but this “green” infrastructure is also important and worth managing, said Jenny Wheeler, Edmonton’s principal of forestry.

The urban forest acts as a wind break, cools the city in the summer, cleans the air and stormwater, and also has a positive impact on people psychologically, she said. The forest management plan will collect information on what’s already growing in the city, a critical update that will help the city plan future planting.
The city takes care of 310,000 trees, with an additional 7,000 planted each year. But Wheeler feels it’s not enough. A detailed on-the-ground survey of 307 sample plots in the city will show her how much tree canopy the city already has and where that’s located. Then she can figure out, in concert with other departments, where more trees should be planted.
Wheeler will have to consider how to accommodate climate change and an advancing wave of insect pests. “Climate change is going to be a big issue for us. If we continue having these dry years, then we have to rethink what we grow. There are people thinking we shouldn’t plant any trees because they’re so hard to sustain. But if you don’t plant trees, you don’t have hope. And trees do so many wonderful things for us. In my mind, we need to continue to plant trees, even though we are struggling with it.”
Edmonton has a harsh climate, so in some ways global warming has opened up opportunities to try other species, such as sugar maples and London plane trees. These are being tested in nurseries or in select areas in the city.
Wheeler said the department will have to change the way some trees are planted. For example, some species won’t be planted on top of hillsides, where they tend to dry out more quickly. Instead, the thirstier trees will be planted in boggy areas. She’s also looking at irrigation as an option. Combining efforts with staff in drainage and transportation means stormwater, which would have run into the river, could be stored and diverted for irrigation, she said.
The other worry that keeps forestry folks like Wheeler on constant alert is the advancing wave of invasive pests and diseases that are waiting to sneak into Edmonton’s forest. Two foes of particular concern are the emerald ash borer, native to eastern Asia, and Dutch elm disease.
On both fronts, the city relies partly on citizens to help them. Firstly, by avoiding certain behaviours, like pruning between April and October in the case of Dutch elm disease. And second, by embracing other behaviours, like watering drought-stricken boulevard trees in dry years such as this one.
A survey of 400 residents this summer showed people, for the most part, agree their urban forest is important and adds value to their lives. The availability of healthy, mature trees is important when deciding to purchase a home, 65 per cent of those surveyed said. Another 73 per cent either supported or somewhat supported establishing guidelines for protection of trees during periods of drought that may include allocating more tax dollars toward the preservation of trees.
Wheeler knows she wants to increase the size of the urban forest, but she’s waiting for the sample plot data to decide what number to aim for. She points at a program in Calgary as a way of increasing the planting in Edmonton.
The BP Birthplace Forest program plants trees in honour of every child born in Calgary. Russell Friesen, Calgary’s urban forestry co-ordinator, helps manage 500,000 trees in the city, but the most important tree there is a ponderosa pine he planted in honour of the birth of his now eight-year-old son, he said.
Calgary created its first urban forestry strategic plan in 1988. It was updated in 2007. It makes sense to have a long-term plan to manage the forest, he said. Trees are the only assets that are alive and last longer than most people, he said. “The trees that were planted generations ago are the ones that this generation prides and cherishes. “Our counterparts who manage oaks in the United Kingdom, they work on a 300-year plan.”
Janice Cooke, a tree biologist at the University of Alberta, applauded the city for tackling a management plan. A consistent policy for the care of trees protects the urban forest during tough economic times, keeping it as a line item even when the budget goes up and down, she said.
Cooke said she has no idea what the management plan is going to include, but one effective option in an urban forest management plan is requiring people to apply for a permit when they want to chop down a tree on private property, she said.
Many trees are taken down when they’re perfectly healthy, she said. At least requiring a permit would make people carefully consider what they want to do.
“Overall, I think that if you have no plan things can happen before you’re even aware. And if you do have a plan you have a chance to guide better what the cityscape looks like and ultimately what Edmonton looks like as a city.”
Related Resources:
Edmonton Journal- New species, irrigation to combat climate change