Monitoring GTA urban forests Regional Standard

NRU
June 8, 2016
Leah Wong

Urban forests play an important role in defending municipalities against climate change by helping to cool communities during extreme heat, prevent flooding and reduce the heat island effect.

To track the health of the urban forest in the Greater Toronto Area the Green Infrastructure Ontario coalition recently released the State of the Urban Forest. The report compiles data from urban forest studies completed by GTA municipalities. Its authors seek to coordinate eff orts to grow and maintain the region’s urban forest.

“We need one standard across the GTA,” City of Toronto councillor and Toronto and Region Conservation Authority board member Glenn De Baermaeker told participants of the Grey to Green Conference in Toronto last week. “Up until this report came along we didn’t exactly know what all of our neighbours were doing [with their urban forests] ... Having a yardstick for us to measure success or failure is very important.”

De Baermaeker noted that municipalities may be hesitant to adopt each other’s standards and that the conservation authorities play an important role as they are considered to be a neutral entity. He added that every municipality participates in conservation authority programs—with representatives on the boards and financial contributions.

The report was compiled using data from urban forest studies completed between 2005 and 2014 by 14 municipalities and four conservation authorities.

“The biggest benefit of the [urban forest] study is being able to utilize the data to generate a specific urban forest management plan for the municipality,” City of Mississauga forestry manager Jessica McEachern told participants. “We were able to utilize the information to formulate a plan for how we’re going to manage those assets over the next 20 years.”

By creating an urban forest management plan, McEachern said the city is able to manage its trees in the same way it would manage grey infrastructure. This includes having an inventory of the location, size and type of trees around the city.

The inventory of trees is important because it shows what trees are threatened by pests. It shows, for example, that ash trees comprise 10 per cent of the tree population in the GTA. Given the presence of emerald ash borer, the region could lose about 3.2-million trees to the disease. This information helps to demonstrate the importance of having a more diverse canopy and inform decisions about the type of trees that should be planted.

The report also shows that only 1 per cent of trees fall within the largest size category-trees that have a diameter of more than 61 cm at breast height. It is recommended that at least 10 per cent of trees fall within the largest size category.

“If you’re going to increase your canopy, protecting the trees you already have is critically important,” York Region forestry and business planning program manager James Lane told participants. “Maintenance is something that is underinvested in in a lot of municipalities.”

He added that knowing the composition of trees allows municipalities to make important decisions about how they allocate forestry resources. In York Region, for example, more resources have been dedicated to maintaining the existing forest in recent years than to planting new trees. This decision was based on the fact that the size and health of a tree affects the benefits it provides-a large, mature tree, for example, can store about 65 times more carbon than one small tree.